[PATCH 0/8] drm/rockchip: vop2: RK3588 clocking, sync polarity, AXI port and window fixes

[PATCH 0/8] drm/rockchip: vop2: RK3588 clocking, sync polarity, AXI port and window fixes

[Arun Iyengar via B4 Relay]

This series collects fixes for the RK3588 VOP2 found while bringing up
HDMI and DisplayPort output on an Orange Pi 5 (RK3588S).

Patches 1 and 2 fix the RK3588 interface setup: rk3588_calc_cru_cfg()
leaves dividers it does not use uninitialised and the garbage ends up in
VP_CLK_CTRL, and rk3588_get_hdmi_pol() decodes the POLFLAG bits it is
handed as DRM mode flags, so the GRF sync polarity bits are wrong for
most modes.

Patch 3 stops the RK3588 Cluster windows from advertising AFBC with the
lossless colour transform (YTR) for RGB565/BGR565, which the decoder
cannot display (black picture plus POST_BUF_EMPTY).

Patches 4 and 5 deal with POST_BUF_EMPTY underflows. The VOP2 fetches
through two AXI read ports but the port of each window is fixed in the
window table, so the usual primary plane plus overlay configuration of
a video port puts both layers on one port while the other sits idle.
One port cannot sustain two full screen 4K@120Hz layers (measured: the
fetch rate collapses from ~6 GB/s to ~3 GB/s and about half of all
lines underflow). Patch 4 assigns the port when a window starts
fetching, balancing the estimated load; patch 5 rate-limits the
POST_BUF_EMPTY interrupt to once per frame, since an underflowing port
otherwise keeps the CPU in the interrupt handler 50000 to 300000 times
per second.

Patches 6 to 8 are smaller fixes: the start mixer search skipped
Esmart3 (for_each_set_bit() was given the highest window id as the bit
count), a gamma LUT update cleared the other fields of LUT_PORT_SEL
(the VP0/VP2 dclk source selection and the VP0/VP1 merge enable), and
the AFBC tile count and transform offset were wrong for a source that
starts inside a 16 pixel superblock.

Tested on an Orange Pi 5 (RK3588S) with an HDMI 2.1 TV and a
DisplayPort monitor, pictures judged with a camera. Patches 1 and 2:
VP0_CLK_CTRL reads back without the garbage dclk_out divider, the sync
polarities seen by the HDMI controller (VIDEO_INTERFACE_STATUS0) match
the mode flags for +/+ (1080p, 2160p) and -/- (720x480, 640x480) modes,
and the picture is correct over TMDS and FRL modes from 27 to
1188 MHz. Patch 3: RGB565 is offered on the Cluster windows only
without YTR, and those planes scan out correctly on three Cluster
windows. Patches 4 and 5: 3840x2160@120 with a full screen overlay
(previously ~120000 POST_BUF_EMPTY per second and a scrambled picture)
and a dual-display session (HDMI 4K@60 plus DP 4K@30, two video players,
ten minutes) run with zero underflows. Patches 6 to 8 were found while
driving Esmart3 and partial AFBC overlays: an AFBC overlay placed at
x=1001 shows correctly. All eight have been in the board's kernel for
the display test runs since.

This series was developed with Claude (Anthropic) as a coding assistant:
it wrote the code and the commit messages, and I reviewed and tested
every change as described above.

Signed-off-by: Arun Iyengar <aiyengar1990@gmail.com>
---
Arun Iyengar (8):
      drm/rockchip: vop2: Don't use uninitialised dividers on RK3588
      drm/rockchip: vop2: Fix the HDMI sync polarity on RK3588
      drm/rockchip: vop2: Don't accept AFBC YTR for RGB565 on RK3588
      drm/rockchip: vop2: Balance window fetches across both AXI ports on RK3588
      drm/rockchip: vop2: Report POST_BUF_EMPTY at most once per frame
      drm/rockchip: vop2: Find the first mixer of a video port with Esmart3 too
      drm/rockchip: vop2: Keep the other LUT_PORT_SEL fields on gamma LUT updates
      drm/rockchip: vop2: Fix the AFBC offsets of a source that starts inside a superblock

 drivers/gpu/drm/rockchip/rockchip_drm_vop2.c | 186 +++++++++++++++++++++++++--
 drivers/gpu/drm/rockchip/rockchip_drm_vop2.h |  24 ++++
 drivers/gpu/drm/rockchip/rockchip_vop2_reg.c |  27 +++-
 3 files changed, 223 insertions(+), 14 deletions(-)
---
base-commit: 8deaade4a5a4ff635df91e246e42139ab2b33f6d
change-id: 20261110-vop2-fixes-fa45142799c1

Best regards,
--  
Arun Iyengar <aiyengar1990@gmail.com>

[PATCH 1/8] drm/rockchip: vop2: Don't use uninitialised dividers on RK3588

[Arun Iyengar via B4 Relay]

From: Arun Iyengar <aiyengar1990@gmail.com>

rk3588_calc_cru_cfg() converts all four dividers to their register
encoding with ilog2(), but only sets the ones the interface uses:
dclk_out_div is left uninitialised for HDMI, eDP and DPI, and
if_pixclk_div/if_dclk_div for DP and DPI. The garbage is then written to
RK3588_VP_CLK_CTRL; on an Orange Pi 5 the dclk_out divider of the HDMI
video port reads back as 3 (/8) in every mode.

Start all dividers at 1. dclk_out only feeds DP and MIPI (and HDMI with
DSC, which is not supported), so for the other interfaces keep it at the
dclk_core rate, as the vendor kernel does for HDMI with DSC, instead of
letting it run at the full DCLK rate.

Fixes: 5a028e8f062f ("drm/rockchip: vop2: Add support for rk3588")
Signed-off-by: Arun Iyengar <aiyengar1990@gmail.com>
---
 drivers/gpu/drm/rockchip/rockchip_vop2_reg.c | 12 ++++++++++++
 1 file changed, 12 insertions(+)

diff --git a/drivers/gpu/drm/rockchip/rockchip_vop2_reg.c b/drivers/gpu/drm/rockchip/rockchip_vop2_reg.c
index c44648e1bc0d..659fd0a3ab63 100644
--- a/drivers/gpu/drm/rockchip/rockchip_vop2_reg.c
+++ b/drivers/gpu/drm/rockchip/rockchip_vop2_reg.c
@@ -1579,6 +1579,15 @@ static unsigned long rk3588_calc_cru_cfg(struct vop2_video_port *vp, int id,
 	unsigned long if_pixclk_rate;
 	int K = 1;
 
+	/*
+	 * Not every interface uses every divider: dclk_out only feeds DP and
+	 * MIPI, the interface dividers are unused for DP. Start from 1 so that
+	 * no divider is left uninitialised when its value is converted below.
+	 */
+	*dclk_out_div = 1;
+	*if_pixclk_div = 1;
+	*if_dclk_div = 1;
+
 	if (vop2_output_if_is_hdmi(id)) {
 		/*
 		 * K = 2: dclk_core = if_pixclk_rate > if_dclk_rate
@@ -1648,6 +1657,9 @@ static unsigned long rk3588_calc_cru_cfg(struct vop2_video_port *vp, int id,
 	}
 
 	*dclk_core_div = dclk_rate / dclk_core_rate;
+	/* An unused dclk_out must not run faster than dclk_core */
+	if (!vop2_output_if_is_dp(id) && !vop2_output_if_is_mipi(id))
+		*dclk_out_div = *dclk_core_div;
 	*if_pixclk_div = ilog2(*if_pixclk_div);
 	*if_dclk_div = ilog2(*if_dclk_div);
 	*dclk_core_div = ilog2(*dclk_core_div);

-- 
2.55.0

[PATCH 2/8] drm/rockchip: vop2: Fix the HDMI sync polarity on RK3588

[Arun Iyengar via B4 Relay]

From: Arun Iyengar <aiyengar1990@gmail.com>

rk3588_set_intf_mux() passes the POLFLAG bits of the mode to
rk3588_get_hdmi_pol(), which decodes them as DRM mode flags: the
VSYNC_POSITIVE bit is taken for DRM_MODE_FLAG_NHSYNC and POLFLAG_DCLK_INV
for DRM_MODE_FLAG_NVSYNC. As a result GRF_VO1_CON0 marks the HSYNC of
every +HSync/+VSync mode (e.g. all 1080p, 2160p CTA modes) as negative
and both syncs of -HSync/-VSync modes (e.g. 720x480, 640x480) as
positive.

The bits in GRF_VO1_CON0 are set for a negative sync; that is how the
vendor kernel programs them (vop2_get_hdmi_pol(), called with the mode
flags, sets them for DRM_MODE_FLAG_NHSYNC/NVSYNC on RK3588). Decode the
POLFLAG bits accordingly.

Fixes: 5a028e8f062f ("drm/rockchip: vop2: Add support for rk3588")
Signed-off-by: Arun Iyengar <aiyengar1990@gmail.com>
---
 drivers/gpu/drm/rockchip/rockchip_vop2_reg.c | 10 +++++++---
 1 file changed, 7 insertions(+), 3 deletions(-)

diff --git a/drivers/gpu/drm/rockchip/rockchip_vop2_reg.c b/drivers/gpu/drm/rockchip/rockchip_vop2_reg.c
index 659fd0a3ab63..7c48b440cb29 100644
--- a/drivers/gpu/drm/rockchip/rockchip_vop2_reg.c
+++ b/drivers/gpu/drm/rockchip/rockchip_vop2_reg.c
@@ -1687,12 +1687,16 @@ static u32 rk3588_get_mipi_port_mux(int vp_id)
 		return 0;
 }
 
-static u32 rk3588_get_hdmi_pol(u32 flags)
+/*
+ * The HDMI sync polarity bits in GRF_VO1_CON0 are set for an active low
+ * (negative) sync.
+ */
+static u32 rk3588_get_hdmi_pol(u32 polflags)
 {
 	u32 val;
 
-	val = (flags & DRM_MODE_FLAG_NHSYNC) ? BIT(HSYNC_POSITIVE) : 0;
-	val |= (flags & DRM_MODE_FLAG_NVSYNC) ? BIT(VSYNC_POSITIVE) : 0;
+	val = (polflags & BIT(HSYNC_POSITIVE)) ? 0 : BIT(HSYNC_POSITIVE);
+	val |= (polflags & BIT(VSYNC_POSITIVE)) ? 0 : BIT(VSYNC_POSITIVE);
 
 	return val;
 }

-- 
2.55.0

[PATCH 3/8] drm/rockchip: vop2: Don't accept AFBC YTR for RGB565 on RK3588

[Arun Iyengar via B4 Relay]

From: Arun Iyengar <aiyengar1990@gmail.com>

The Cluster windows of the RK3588 VOP2 advertise every AFBC modifier
of format_modifiers_afbc for RGB565 and BGR565, including the ones
with the lossless colour transform (YTR). Scanning out an RGB565
buffer rendered by the Mali-G610 (panfrost) with
AFBC(16x16 | SPARSE | YTR) gives a black picture and POST_BUF_EMPTY
on the video port, on every Cluster window, while the same buffer
rendered with AFBC(16x16 | SPARSE) displays correctly, as do 32 bpp
formats with YTR.

YTR on RGB565 is also a questionable pairing to start with:
Documentation/gpu/afbc.rst requires the R, G, B component order when
YTR is used, with component 0 in the least significant bits, which
DRM_FORMAT_RGB565 (B in the low bits) doesn't have, and the Arm
Mali-D71 (komeda) only accepts AFBC for BGR565.

Stop advertising and accepting YTR for the two 16 bpp RGB formats on
RK3588, so that userspace picks a modifier the decoder handles. The
BGR565 case could not be tested (Mesa can't import BGR565 dma-bufs),
it's rejected as well because the decoder is configured identically
for both formats, apart from the R/B swap after decoding.

Fixes: 5a028e8f062f ("drm/rockchip: vop2: Add support for rk3588")
Signed-off-by: Arun Iyengar <aiyengar1990@gmail.com>
---
 drivers/gpu/drm/rockchip/rockchip_drm_vop2.c | 12 ++++++++++++
 1 file changed, 12 insertions(+)

diff --git a/drivers/gpu/drm/rockchip/rockchip_drm_vop2.c b/drivers/gpu/drm/rockchip/rockchip_drm_vop2.c
index 76d151b8bc52..629ea7f11250 100644
--- a/drivers/gpu/drm/rockchip/rockchip_drm_vop2.c
+++ b/drivers/gpu/drm/rockchip/rockchip_drm_vop2.c
@@ -404,6 +404,18 @@ static bool rockchip_vop2_mod_supported(struct drm_plane *plane, u32 format,
 	if (vop2_convert_afbc_format(format) == VOP2_AFBC_FMT_INVALID)
 		return false;
 
+	/*
+	 * The AFBC decoder of the RK3588 Cluster windows can't decode 16 bpp
+	 * RGB that uses the lossless colour transform: the picture stays
+	 * black and the video port reports POST_BUF_EMPTY, while the same
+	 * buffers without YTR display fine.
+	 */
+	if (vop2->version == VOP_VERSION_RK3588 && (modifier & AFBC_FORMAT_MOD_YTR) &&
+	    (format == DRM_FORMAT_RGB565 || format == DRM_FORMAT_BGR565)) {
+		drm_dbg_kms(vop2->drm, "No AFBC YTR support for 16 bpp RGB\n");
+		return false;
+	}
+
 	/* Different windows have different format/modifier support */
 	for (i = 0; i < plane->modifier_count; i++) {
 		if (plane->modifiers[i] == modifier)

-- 
2.55.0

[PATCH 4/8] drm/rockchip: vop2: Balance window fetches across both AXI ports on RK3588

[Arun Iyengar via B4 Relay]

From: Arun Iyengar <aiyengar1990@gmail.com>

The RK3588 VOP2 fetches through two AXI read ports. Every window has a
fixed default port in rk3588_vop_win_data: Cluster0/1 and Esmart0/1 use
AXI0, Cluster2/3 and Esmart2/3 use AXI1. The port is chosen by a per
window register (CLUSTER_CTRL[13] / ESMART_AXI_CTRL[1]), though, and it
is programmed on every plane update.

One port can't sustain two full screen 4K@120Hz layers. With the
console on Cluster0 (the primary plane of video port 0) and a video on
Esmart0 (its overlay plane), both on AXI0, HDMI 3840x2160@120 reports
POST_BUF_EMPTY on about half of all lines (~120000 per second) and the
picture is scrambled. The VOP read rate measured with the DDR PMU drops
from the expected 6.3 GB/s to 3.2 GB/s: the fetch collapses instead of
merely saturating. Measured at 4K@120Hz, XR24 primary plane:

  Cluster0 + Esmart0 (AXI0 + AXI0)	~120k POST_BUF_EMPTY/s
  Cluster2 + Esmart2 (AXI1 + AXI1)	~100k/s
  Esmart0 + Esmart1  (AXI0 + AXI0)	~90k/s (XR24 both)
  Cluster0 + Esmart2 (AXI0 + AXI1)	0, 9.2 GB/s read
  Cluster0 + Cluster2 (AXI0 + AXI1)	0, 8.6 GB/s read

Moving Esmart0 to AXI1 at runtime (with no other change) makes the
first case clean. Raising ACLK_VOP from 750 to 850 MHz, or changing
the NoC QoS priority or mode of the VOP ports, makes no difference,
and neither does the buffer placement (both planes scanning out the
same buffer fail the same way). So the limit is per port, and the
fixed assignment puts both layers of the most common configuration on
the same port while the other one sits idle. Lower modes are affected
too: the same port also carries Cluster1 for a second display, and
under DDR contention from other masters a 4K@60Hz port with the
console, an overlay and a second display underflows for short bursts.

Choose the port of a window when it starts fetching instead: estimate
the fetch rate of each active window (source size x bpp x refresh),
and put the new window on the port that leaves the busier port least
loaded, preferring the default one on a tie. A window must not share
an AXI read ID with another active window on the same port; the IDs in
the table are unique per default port, and mirrored between the two
ports (Cluster0/Cluster2, Esmart0/Esmart2, ...), so a window can always
use the port its mirror isn't on. A window keeps its port while it
stays enabled, so an active layer is never moved.

This is only enabled for RK3588, where it was measured.

Signed-off-by: Arun Iyengar <aiyengar1990@gmail.com>
---
 drivers/gpu/drm/rockchip/rockchip_drm_vop2.c | 99 +++++++++++++++++++++++++++-
 drivers/gpu/drm/rockchip/rockchip_drm_vop2.h | 14 ++++
 drivers/gpu/drm/rockchip/rockchip_vop2_reg.c |  3 +-
 3 files changed, 114 insertions(+), 2 deletions(-)

diff --git a/drivers/gpu/drm/rockchip/rockchip_drm_vop2.c b/drivers/gpu/drm/rockchip/rockchip_drm_vop2.c
index 629ea7f11250..9aeb90c6aa4b 100644
--- a/drivers/gpu/drm/rockchip/rockchip_drm_vop2.c
+++ b/drivers/gpu/drm/rockchip/rockchip_drm_vop2.c
@@ -1231,6 +1231,98 @@ static int vop2_plane_atomic_check(struct drm_plane *plane,
 	return 0;
 }
 
+static bool vop2_win_axi_ids_clash(const struct vop2_win *a, const struct vop2_win *b)
+{
+	u8 ida[] = { a->data->axi_yrgb_r_id, a->data->axi_uv_r_id };
+	u8 idb[] = { b->data->axi_yrgb_r_id, b->data->axi_uv_r_id };
+	int i, j;
+
+	for (i = 0; i < ARRAY_SIZE(ida); i++)
+		for (j = 0; j < ARRAY_SIZE(idb); j++)
+			if (ida[i] == idb[j])
+				return true;
+
+	return false;
+}
+
+/*
+ * The VOP2 on RK3588 has two AXI read ports. Each window has a default port
+ * (&vop2_win_data.axi_bus_id), but the port is selected by a per window
+ * register, so any window can fetch through either one as long as its read
+ * IDs are unique on that port.
+ *
+ * A single port can't sustain much more than one full screen 4K@120Hz
+ * layer: two such layers on the same port (e.g. Cluster0 and Esmart0, the
+ * default primary and overlay planes of video port 0) make the window
+ * line buffers run dry, the fetch rate collapses and the video port
+ * reports POST_BUF_EMPTY on most lines, which scrambles the picture. The
+ * same layers fetched through different ports are fine. Raising ACLK or
+ * the NoC priority of the VOP doesn't help, the limit is per port.
+ *
+ * So pick the port of a window when it starts fetching: use the port that
+ * leaves the busier of the two ports least loaded, preferring the default
+ * one, and never a port on which another active window already uses one of
+ * its read IDs. A window keeps its port while it stays enabled.
+ */
+static u8 vop2_win_get_axi_bus(struct vop2_win *win, u64 load)
+{
+	struct vop2 *vop2 = win->vop2;
+	u64 bus_load[VOP2_SYS_AXI_BUS_NUM] = { };
+	bool clash[VOP2_SYS_AXI_BUS_NUM] = { };
+	u8 def = win->data->axi_bus_id;
+	unsigned long flags;
+	u8 bus = def;
+	int i;
+
+	if (!(vop2->data->feature & VOP2_FEATURE_AXI_BALANCE))
+		return def;
+
+	spin_lock_irqsave(&vop2->axi_lock, flags);
+
+	if (win->axi_active) {
+		win->axi_load = load;
+		bus = win->axi_bus;
+		goto out;
+	}
+
+	for (i = 0; i < vop2->registered_num_wins; i++) {
+		struct vop2_win *w = &vop2->win[i];
+
+		if (w == win || !w->axi_active)
+			continue;
+
+		bus_load[w->axi_bus] += w->axi_load;
+		if (vop2_win_axi_ids_clash(win, w))
+			clash[w->axi_bus] = true;
+	}
+
+	if (!clash[def ^ 1] &&
+	    (clash[def] || max(bus_load[def ^ 1] + load, bus_load[def]) <
+			   max(bus_load[def] + load, bus_load[def ^ 1])))
+		bus = def ^ 1;
+
+	WARN_ON_ONCE(clash[bus]);
+
+	win->axi_bus = bus;
+	win->axi_load = load;
+	win->axi_active = true;
+out:
+	spin_unlock_irqrestore(&vop2->axi_lock, flags);
+
+	return bus;
+}
+
+static void vop2_win_put_axi_bus(struct vop2_win *win)
+{
+	struct vop2 *vop2 = win->vop2;
+	unsigned long flags;
+
+	spin_lock_irqsave(&vop2->axi_lock, flags);
+	win->axi_active = false;
+	win->axi_load = 0;
+	spin_unlock_irqrestore(&vop2->axi_lock, flags);
+}
+
 static void vop2_plane_atomic_disable(struct drm_plane *plane,
 				      struct drm_atomic_commit *state)
 {
@@ -1241,6 +1333,8 @@ static void vop2_plane_atomic_disable(struct drm_plane *plane,
 
 	drm_dbg(vop2->drm, "%s disable\n", win->data->name);
 
+	vop2_win_put_axi_bus(win);
+
 	if (state)
 		old_pstate = drm_atomic_get_old_plane_state(state, plane);
 
@@ -1416,7 +1510,9 @@ static void vop2_plane_atomic_update(struct drm_plane *plane,
 		afbc_en ? "AFBC" : "", &yrgb_mst);
 
 	if (vop2->version > VOP_VERSION_RK3568) {
-		vop2_win_write(win, VOP2_WIN_AXI_BUS_ID, win->data->axi_bus_id);
+		u64 load = (u64)src_w * src_h * bpp / 8 * drm_mode_vrefresh(adjusted_mode);
+
+		vop2_win_write(win, VOP2_WIN_AXI_BUS_ID, vop2_win_get_axi_bus(win, load));
 		vop2_win_write(win, VOP2_WIN_AXI_YRGB_R_ID, win->data->axi_yrgb_r_id);
 		vop2_win_write(win, VOP2_WIN_AXI_UV_R_ID, win->data->axi_uv_r_id);
 	}
@@ -3005,6 +3101,7 @@ static int vop2_bind(struct device *dev, struct device *master, void *data)
 
 	mutex_init(&vop2->vop2_lock);
 	mutex_init(&vop2->ovl_lock);
+	spin_lock_init(&vop2->axi_lock);
 
 	ret = devm_request_irq(dev, vop2->irq, vop2_isr, IRQF_SHARED, dev_name(dev), vop2);
 	if (ret)
diff --git a/drivers/gpu/drm/rockchip/rockchip_drm_vop2.h b/drivers/gpu/drm/rockchip/rockchip_drm_vop2.h
index 1c2d7d97a6c2..f1e35967e67f 100644
--- a/drivers/gpu/drm/rockchip/rockchip_drm_vop2.h
+++ b/drivers/gpu/drm/rockchip/rockchip_drm_vop2.h
@@ -29,6 +29,7 @@
 #define VOP2_FEATURE_HAS_VO1_GRF	BIT(2)
 #define VOP2_FEATURE_HAS_VOP_GRF	BIT(3)
 #define VOP2_FEATURE_HAS_SYS_PMU	BIT(4)
+#define VOP2_FEATURE_AXI_BALANCE	BIT(5)
 
 #define WIN_FEATURE_AFBDC		BIT(0)
 #define WIN_FEATURE_CLUSTER		BIT(1)
@@ -219,6 +220,16 @@ struct vop2_win {
 	u32 offset;
 
 	enum drm_plane_type type;
+
+	/**
+	 * @axi_bus: AXI read port the window currently fetches through,
+	 * protected by &vop2.axi_lock.
+	 */
+	u8 axi_bus;
+	/** @axi_active: the window is fetching, protected by &vop2.axi_lock */
+	bool axi_active;
+	/** @axi_load: estimated fetch rate in bytes/s, protected by &vop2.axi_lock */
+	u64 axi_load;
 };
 
 struct vop2_video_port_data {
@@ -356,6 +367,9 @@ struct vop2 {
 	 */
 	struct mutex ovl_lock;
 
+	/* protects the AXI port assignment of all windows (&vop2_win.axi_bus) */
+	spinlock_t axi_lock;
+
 	/* must be put at the end of the struct */
 	struct vop2_win win[];
 };
diff --git a/drivers/gpu/drm/rockchip/rockchip_vop2_reg.c b/drivers/gpu/drm/rockchip/rockchip_vop2_reg.c
index 7c48b440cb29..83203d18865b 100644
--- a/drivers/gpu/drm/rockchip/rockchip_vop2_reg.c
+++ b/drivers/gpu/drm/rockchip/rockchip_vop2_reg.c
@@ -2577,7 +2577,8 @@ static const struct vop2_data rk3576_vop = {
 static const struct vop2_data rk3588_vop = {
 	.version = VOP_VERSION_RK3588,
 	.feature = VOP2_FEATURE_HAS_SYS_GRF | VOP2_FEATURE_HAS_VO1_GRF |
-		   VOP2_FEATURE_HAS_VOP_GRF | VOP2_FEATURE_HAS_SYS_PMU,
+		   VOP2_FEATURE_HAS_VOP_GRF | VOP2_FEATURE_HAS_SYS_PMU |
+		   VOP2_FEATURE_AXI_BALANCE,
 	.nr_vps = 4,
 	.max_input = { 4096, 4320 },
 	.max_output = { 4096, 4320 },

-- 
2.55.0

[PATCH 5/8] drm/rockchip: vop2: Report POST_BUF_EMPTY at most once per frame

[Arun Iyengar via B4 Relay]

From: Arun Iyengar <aiyengar1990@gmail.com>

POST_BUF_EMPTY is raised for every line on which the post processing
stage of a video port finds no data. The interrupt handler only
rate-limits the error message and leaves the interrupt enabled, so an
underflowing video port keeps the CPU in the interrupt handler 50000 to
300000 times per second, for as long as the configuration that causes
the underflow stays in place (e.g. 120000 interrupts per second for
3840x2160@120 with two full screen layers on one AXI port).

Mask POST_BUF_EMPTY when it fires and unmask it at the next frame start.
The frame start (FS) interrupt is enabled for that frame even when
vblank reporting is off, and disabled again once POST_BUF_EMPTY is
re-armed. A new per video port lock serialises the interrupt enable
bookkeeping between the interrupt handler and the vblank callbacks.
The error is still reported, now at most once per frame and video port.

Signed-off-by: Arun Iyengar <aiyengar1990@gmail.com>
---
 drivers/gpu/drm/rockchip/rockchip_drm_vop2.c | 63 ++++++++++++++++++++++++++--
 drivers/gpu/drm/rockchip/rockchip_drm_vop2.h | 10 +++++
 2 files changed, 70 insertions(+), 3 deletions(-)

diff --git a/drivers/gpu/drm/rockchip/rockchip_drm_vop2.c b/drivers/gpu/drm/rockchip/rockchip_drm_vop2.c
index 9aeb90c6aa4b..3323e50224c5 100644
--- a/drivers/gpu/drm/rockchip/rockchip_drm_vop2.c
+++ b/drivers/gpu/drm/rockchip/rockchip_drm_vop2.c
@@ -841,6 +841,48 @@ static void vop2_crtc_disable_irq(struct vop2_video_port *vp, u32 irq)
 	vop2_writel(vop2, RK3568_VP_INT_EN(vp->id), irq << 16);
 }
 
+/*
+ * POST_BUF_EMPTY is raised for every line the post processing stage finds
+ * no data for, so an underflowing video port can raise it 100000 times per
+ * second. Report it at most once per frame: mask it when it fires and
+ * unmask it at the next frame start, using the FS interrupt even when
+ * vblank reporting is off.
+ */
+static void vop2_crtc_enable_post_buf_empty_irq(struct vop2_video_port *vp)
+{
+	unsigned long flags;
+
+	spin_lock_irqsave(&vp->irq_lock, flags);
+	vp->post_buf_empty_masked = false;
+	vop2_crtc_enable_irq(vp, VP_INT_POST_BUF_EMPTY);
+	spin_unlock_irqrestore(&vp->irq_lock, flags);
+}
+
+static void vop2_crtc_handle_post_buf_empty(struct vop2_video_port *vp)
+{
+	struct vop2 *vop2 = vp->vop2;
+
+	spin_lock(&vp->irq_lock);
+	vop2_crtc_disable_irq(vp, VP_INT_POST_BUF_EMPTY);
+	vp->post_buf_empty_masked = true;
+	/* don't clear a pending FS, it may carry a vblank event */
+	vop2_writel(vop2, RK3568_VP_INT_EN(vp->id),
+		    VP_INT_FS_FIELD << 16 | VP_INT_FS_FIELD);
+	spin_unlock(&vp->irq_lock);
+}
+
+static void vop2_crtc_rearm_post_buf_empty(struct vop2_video_port *vp)
+{
+	spin_lock(&vp->irq_lock);
+	if (vp->post_buf_empty_masked) {
+		vp->post_buf_empty_masked = false;
+		vop2_crtc_enable_irq(vp, VP_INT_POST_BUF_EMPTY);
+		if (!vp->vblank_enabled)
+			vop2_crtc_disable_irq(vp, VP_INT_FS_FIELD);
+	}
+	spin_unlock(&vp->irq_lock);
+}
+
 static int vop2_core_clks_prepare_enable(struct vop2 *vop2)
 {
 	int ret;
@@ -1668,8 +1710,12 @@ static const struct drm_plane_funcs vop2_plane_funcs = {
 static int vop2_crtc_enable_vblank(struct drm_crtc *crtc)
 {
 	struct vop2_video_port *vp = to_vop2_video_port(crtc);
+	unsigned long flags;
 
+	spin_lock_irqsave(&vp->irq_lock, flags);
+	vp->vblank_enabled = true;
 	vop2_crtc_enable_irq(vp, VP_INT_FS_FIELD);
+	spin_unlock_irqrestore(&vp->irq_lock, flags);
 
 	return 0;
 }
@@ -1677,8 +1723,13 @@ static int vop2_crtc_enable_vblank(struct drm_crtc *crtc)
 static void vop2_crtc_disable_vblank(struct drm_crtc *crtc)
 {
 	struct vop2_video_port *vp = to_vop2_video_port(crtc);
+	unsigned long flags;
 
-	vop2_crtc_disable_irq(vp, VP_INT_FS_FIELD);
+	spin_lock_irqsave(&vp->irq_lock, flags);
+	vp->vblank_enabled = false;
+	if (!vp->post_buf_empty_masked)
+		vop2_crtc_disable_irq(vp, VP_INT_FS_FIELD);
+	spin_unlock_irqrestore(&vp->irq_lock, flags);
 }
 
 static enum drm_mode_status vop2_crtc_mode_valid(struct drm_crtc *crtc,
@@ -1977,7 +2028,7 @@ static void vop2_crtc_atomic_enable(struct drm_crtc *crtc,
 
 	vcstate->yuv_overlay = is_yuv_output(vcstate->bus_format);
 
-	vop2_crtc_enable_irq(vp, VP_INT_POST_BUF_EMPTY);
+	vop2_crtc_enable_post_buf_empty_irq(vp);
 
 	polflags = 0;
 	if (vcstate->bus_flags & DRM_BUS_FLAG_PIXDATA_DRIVE_NEGEDGE)
@@ -2535,6 +2586,7 @@ static irqreturn_t rk3576_vp_isr(int irq, void *data)
 	}
 
 	if (irqs & VP_INT_FS_FIELD) {
+		vop2_crtc_rearm_post_buf_empty(vp);
 		drm_crtc_handle_vblank(crtc);
 		spin_lock(&crtc->dev->event_lock);
 		if (vp->event) {
@@ -2552,6 +2604,7 @@ static irqreturn_t rk3576_vp_isr(int irq, void *data)
 	}
 
 	if (irqs & VP_INT_POST_BUF_EMPTY) {
+		vop2_crtc_handle_post_buf_empty(vp);
 		drm_err_ratelimited(vop2->drm, "POST_BUF_EMPTY irq err at vp%d\n", vp->id);
 		ret = IRQ_HANDLED;
 	}
@@ -2591,6 +2644,7 @@ static irqreturn_t vop2_isr(int irq, void *data)
 			}
 
 			if (irqs & VP_INT_FS_FIELD) {
+				vop2_crtc_rearm_post_buf_empty(vp);
 				drm_crtc_handle_vblank(crtc);
 				spin_lock(&crtc->dev->event_lock);
 				if (vp->event) {
@@ -2608,6 +2662,7 @@ static irqreturn_t vop2_isr(int irq, void *data)
 			}
 
 			if (irqs & VP_INT_POST_BUF_EMPTY) {
+				vop2_crtc_handle_post_buf_empty(vp);
 				drm_err_ratelimited(vop2->drm,
 						    "POST_BUF_EMPTY irq err at vp%d\n",
 						    vp->id);
@@ -2984,7 +3039,7 @@ static int vop2_bind(struct device *dev, struct device *master, void *data)
 	struct vop2 *vop2;
 	struct resource *res;
 	size_t alloc_size;
-	int ret;
+	int ret, i;
 
 	vop2_data = of_device_get_match_data(dev);
 	if (!vop2_data)
@@ -3102,6 +3157,8 @@ static int vop2_bind(struct device *dev, struct device *master, void *data)
 	mutex_init(&vop2->vop2_lock);
 	mutex_init(&vop2->ovl_lock);
 	spin_lock_init(&vop2->axi_lock);
+	for (i = 0; i < ARRAY_SIZE(vop2->vps); i++)
+		spin_lock_init(&vop2->vps[i].irq_lock);
 
 	ret = devm_request_irq(dev, vop2->irq, vop2_isr, IRQF_SHARED, dev_name(dev), vop2);
 	if (ret)
diff --git a/drivers/gpu/drm/rockchip/rockchip_drm_vop2.h b/drivers/gpu/drm/rockchip/rockchip_drm_vop2.h
index f1e35967e67f..7de32bef8d7b 100644
--- a/drivers/gpu/drm/rockchip/rockchip_drm_vop2.h
+++ b/drivers/gpu/drm/rockchip/rockchip_drm_vop2.h
@@ -272,6 +272,16 @@ struct vop2_video_port {
 	struct drm_pending_vblank_event *event;
 
 	unsigned int nlayers;
+
+	/** @irq_lock: protects @vblank_enabled and @post_buf_empty_masked */
+	spinlock_t irq_lock;
+	/** @vblank_enabled: the FS interrupt is enabled for vblank reporting */
+	bool vblank_enabled;
+	/**
+	 * @post_buf_empty_masked: POST_BUF_EMPTY is masked until the next
+	 * frame start
+	 */
+	bool post_buf_empty_masked;
 };
 
 /**

-- 
2.55.0

[PATCH 6/8] drm/rockchip: vop2: Find the first mixer of a video port with Esmart3 too

[Arun Iyengar via B4 Relay]

From: Arun Iyengar <aiyengar1990@gmail.com>

vop2_find_start_mixer_id_for_vp() looks for the first layer that holds a
window of the video port, but for_each_set_bit() takes the number of bits
to search, and ROCKCHIP_VOP2_ESMART3 is the highest window id, so Esmart3
is never found. A video port whose bottom layer shows Esmart3 then starts
its alpha setup at the mixer of a higher layer, or, if Esmart3 is its
only window, past all layers, and programs mixers of other video ports.

Search all window ids.

Signed-off-by: Arun Iyengar <aiyengar1990@gmail.com>
---
 drivers/gpu/drm/rockchip/rockchip_vop2_reg.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/gpu/drm/rockchip/rockchip_vop2_reg.c b/drivers/gpu/drm/rockchip/rockchip_vop2_reg.c
index 83203d18865b..2843bfb36341 100644
--- a/drivers/gpu/drm/rockchip/rockchip_vop2_reg.c
+++ b/drivers/gpu/drm/rockchip/rockchip_vop2_reg.c
@@ -1889,7 +1889,7 @@ static int vop2_find_start_mixer_id_for_vp(struct vop2_video_port *vp)
 
 	for (i = 0; i < 31; i += 4) {
 		match = false;
-		for_each_set_bit(phys_id, &win_mask, ROCKCHIP_VOP2_ESMART3) {
+		for_each_set_bit(phys_id, &win_mask, ROCKCHIP_VOP2_ESMART3 + 1) {
 			win = vop2_find_win_by_phys_id(vop2, phys_id);
 			if (win->data->layer_sel_id[vp->id] == ((layer_sel >> i) & 0xf)) {
 				match = true;

-- 
2.55.0

[PATCH 7/8] drm/rockchip: vop2: Keep the other LUT_PORT_SEL fields on gamma LUT updates

[Arun Iyengar via B4 Relay]

From: Arun Iyengar <aiyengar1990@gmail.com>

On RK3588 the gamma LUT of a video port is written through a window that
GAMMA_AHB_WRITE_SEL in SYS_CTRL_LUT_PORT_SEL selects. The register also
holds the dclk source selection of video ports 0 and 2 and the enable of
the video port 0/1 merge for modes wider than 4096 pixels, which writing
the whole register clears.

Only update the write select field.

Signed-off-by: Arun Iyengar <aiyengar1990@gmail.com>
---
 drivers/gpu/drm/rockchip/rockchip_drm_vop2.c | 5 +++--
 1 file changed, 3 insertions(+), 2 deletions(-)

diff --git a/drivers/gpu/drm/rockchip/rockchip_drm_vop2.c b/drivers/gpu/drm/rockchip/rockchip_drm_vop2.c
index 3323e50224c5..9ad138457204 100644
--- a/drivers/gpu/drm/rockchip/rockchip_drm_vop2.c
+++ b/drivers/gpu/drm/rockchip/rockchip_drm_vop2.c
@@ -1774,8 +1774,9 @@ static void vop2_crtc_atomic_set_gamma_seamless(struct vop2 *vop2,
 						struct vop2_video_port *vp,
 						struct drm_crtc *crtc)
 {
-	vop2_writel(vop2, RK3568_LUT_PORT_SEL,
-		    FIELD_PREP(RK3588_LUT_PORT_SEL__GAMMA_AHB_WRITE_SEL, vp->id));
+	regmap_update_bits(vop2->map, RK3568_LUT_PORT_SEL,
+			   RK3588_LUT_PORT_SEL__GAMMA_AHB_WRITE_SEL,
+			   FIELD_PREP(RK3588_LUT_PORT_SEL__GAMMA_AHB_WRITE_SEL, vp->id));
 	vop2_vp_dsp_lut_enable(vp);
 	vop2_crtc_write_gamma_lut(vop2, crtc);
 	vop2_vp_dsp_lut_update_enable(vp);

-- 
2.55.0

[PATCH 8/8] drm/rockchip: vop2: Fix the AFBC offsets of a source that starts inside a superblock

[Arun Iyengar via B4 Relay]

From: Arun Iyengar <aiyengar1990@gmail.com>

The AFBC decoder of a window takes the position of the source in the
framebuffer (AFBC_PIC_OFFSET), the number of superblock columns to
decode (AFBC_TILE_NUM) and the offset of the first pixel inside its
superblock (the transform offset). For a source that doesn't start at
x = 0:

- The tile number only counts the superblocks of the source width, one
  short when the source starts inside a superblock and ends inside
  another one.
- The transform offset is the whole x position, truncated to the 8 bit
  field, instead of the position in the 16 pixel wide superblock.

Count the superblock columns from the first one the source touches, and
take the x offset in the superblock, like the vendor kernel does for the
not mirrored cases. The X mirrored and rotated cases are left as they are.

Signed-off-by: Arun Iyengar <aiyengar1990@gmail.com>
---
 drivers/gpu/drm/rockchip/rockchip_drm_vop2.c | 7 ++++---
 1 file changed, 4 insertions(+), 3 deletions(-)

diff --git a/drivers/gpu/drm/rockchip/rockchip_drm_vop2.c b/drivers/gpu/drm/rockchip/rockchip_drm_vop2.c
index 9ad138457204..dfb76bfbc358 100644
--- a/drivers/gpu/drm/rockchip/rockchip_drm_vop2.c
+++ b/drivers/gpu/drm/rockchip/rockchip_drm_vop2.c
@@ -486,7 +486,7 @@ static u32 vop2_afbc_transform_offset(struct drm_plane_state *pstate,
 		ty = act_yoffset;
 		break;
 	case DRM_MODE_REFLECT_Y:
-		tx = act_xoffset;
+		tx = act_xoffset & 0xf;
 		ty = bottom_crop_line_num - act_yoffset;
 		break;
 	case DRM_MODE_ROTATE_90:
@@ -498,7 +498,7 @@ static u32 vop2_afbc_transform_offset(struct drm_plane_state *pstate,
 		ty = vir_width - width - act_xoffset;
 		break;
 	case 0:
-		tx = act_xoffset;
+		tx = act_xoffset & 0xf;
 		ty = act_yoffset;
 		break;
 	}
@@ -1577,7 +1577,8 @@ static void vop2_plane_atomic_update(struct drm_plane *plane,
 		if (fb->modifier & AFBC_FORMAT_MOD_YTR)
 			afbc_format |= (1 << 4);
 
-		afbc_tile_num = ALIGN(src_w, block_w) / block_w;
+		/* Superblock columns the source covers, the first one partly */
+		afbc_tile_num = ALIGN(src_w + (src->x1 >> 16) % block_w, block_w) / block_w;
 
 		/*
 		 * AFBC pic_vir_width is count by pixel, this is different

-- 
2.55.0

Re: [PATCH 0/8] drm/rockchip: vop2: RK3588 clocking, sync polarity, AXI port and window fixes

[Chaoyi Chen]

Hi Arun,

On 11/10/2026 3:18 PM, Arun Iyengar via B4 Relay wrote:
> This series collects fixes for the RK3588 VOP2 found while bringing up
> HDMI and DisplayPort output on an Orange Pi 5 (RK3588S).
> 
> Patches 1 and 2 fix the RK3588 interface setup: rk3588_calc_cru_cfg()
> leaves dividers it does not use uninitialised and the garbage ends up in
> VP_CLK_CTRL, and rk3588_get_hdmi_pol() decodes the POLFLAG bits it is
> handed as DRM mode flags, so the GRF sync polarity bits are wrong for
> most modes.
> 
> Patch 3 stops the RK3588 Cluster windows from advertising AFBC with the
> lossless colour transform (YTR) for RGB565/BGR565, which the decoder
> cannot display (black picture plus POST_BUF_EMPTY).
> 
> Patches 4 and 5 deal with POST_BUF_EMPTY underflows. The VOP2 fetches
> through two AXI read ports but the port of each window is fixed in the
> window table, so the usual primary plane plus overlay configuration of
> a video port puts both layers on one port while the other sits idle.
> One port cannot sustain two full screen 4K@120Hz layers (measured: the
> fetch rate collapses from ~6 GB/s to ~3 GB/s and about half of all
> lines underflow). Patch 4 assigns the port when a window starts
> fetching, balancing the estimated load; patch 5 rate-limits the
> POST_BUF_EMPTY interrupt to once per frame, since an underflowing port
> otherwise keeps the CPU in the interrupt handler 50000 to 300000 times
> per second.
> 

Have you checked the aclk_vop rate?

> Patches 6 to 8 are smaller fixes: the start mixer search skipped
> Esmart3 (for_each_set_bit() was given the highest window id as the bit
> count), a gamma LUT update cleared the other fields of LUT_PORT_SEL
> (the VP0/VP2 dclk source selection and the VP0/VP1 merge enable), and
> the AFBC tile count and transform offset were wrong for a source that
> starts inside a 16 pixel superblock.
> 
> Tested on an Orange Pi 5 (RK3588S) with an HDMI 2.1 TV and a
> DisplayPort monitor, pictures judged with a camera. Patches 1 and 2:
> VP0_CLK_CTRL reads back without the garbage dclk_out divider, the sync
> polarities seen by the HDMI controller (VIDEO_INTERFACE_STATUS0) match
> the mode flags for +/+ (1080p, 2160p) and -/- (720x480, 640x480) modes,
> and the picture is correct over TMDS and FRL modes from 27 to
> 1188 MHz. Patch 3: RGB565 is offered on the Cluster windows only
> without YTR, and those planes scan out correctly on three Cluster
> windows. Patches 4 and 5: 3840x2160@120 with a full screen overlay
> (previously ~120000 POST_BUF_EMPTY per second and a scrambled picture)
> and a dual-display session (HDMI 4K@60 plus DP 4K@30, two video players,
> ten minutes) run with zero underflows. Patches 6 to 8 were found while
> driving Esmart3 and partial AFBC overlays: an AFBC overlay placed at
> x=1001 shows correctly. All eight have been in the board's kernel for
> the display test runs since.
> 
> This series was developed with Claude (Anthropic) as a coding assistant:
> it wrote the code and the commit messages, and I reviewed and tested
> every change as described above.
> 
> Signed-off-by: Arun Iyengar <aiyengar1990@gmail.com>
> ---
> Arun Iyengar (8):
>       drm/rockchip: vop2: Don't use uninitialised dividers on RK3588
>       drm/rockchip: vop2: Fix the HDMI sync polarity on RK3588
>       drm/rockchip: vop2: Don't accept AFBC YTR for RGB565 on RK3588
>       drm/rockchip: vop2: Balance window fetches across both AXI ports on RK3588
>       drm/rockchip: vop2: Report POST_BUF_EMPTY at most once per frame
>       drm/rockchip: vop2: Find the first mixer of a video port with Esmart3 too
>       drm/rockchip: vop2: Keep the other LUT_PORT_SEL fields on gamma LUT updates
>       drm/rockchip: vop2: Fix the AFBC offsets of a source that starts inside a superblock
> 
>  drivers/gpu/drm/rockchip/rockchip_drm_vop2.c | 186 +++++++++++++++++++++++++--
>  drivers/gpu/drm/rockchip/rockchip_drm_vop2.h |  24 ++++
>  drivers/gpu/drm/rockchip/rockchip_vop2_reg.c |  27 +++-
>  3 files changed, 223 insertions(+), 14 deletions(-)
> ---
> base-commit: 8deaade4a5a4ff635df91e246e42139ab2b33f6d
> change-id: 20261110-vop2-fixes-fa45142799c1
> 
> Best regards,
> --  
> Arun Iyengar <aiyengar1990@gmail.com>

-- 
Best, 
Chaoyi

Re: [PATCH 6/8] drm/rockchip: vop2: Find the first mixer of a video port with Esmart3 too

[Chaoyi Chen]

Hi Arun,

On 11/10/2026 3:18 PM, Arun Iyengar via B4 Relay wrote:
> From: Arun Iyengar <aiyengar1990@gmail.com>
> 
> vop2_find_start_mixer_id_for_vp() looks for the first layer that holds a
> window of the video port, but for_each_set_bit() takes the number of bits
> to search, and ROCKCHIP_VOP2_ESMART3 is the highest window id, so Esmart3
> is never found. A video port whose bottom layer shows Esmart3 then starts
> its alpha setup at the mixer of a higher layer, or, if Esmart3 is its
> only window, past all layers, and programs mixers of other video ports.
> 
> Search all window ids.
> 
> Signed-off-by: Arun Iyengar <aiyengar1990@gmail.com>
> ---
>  drivers/gpu/drm/rockchip/rockchip_vop2_reg.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/drivers/gpu/drm/rockchip/rockchip_vop2_reg.c b/drivers/gpu/drm/rockchip/rockchip_vop2_reg.c
> index 83203d18865b..2843bfb36341 100644
> --- a/drivers/gpu/drm/rockchip/rockchip_vop2_reg.c
> +++ b/drivers/gpu/drm/rockchip/rockchip_vop2_reg.c
> @@ -1889,7 +1889,7 @@ static int vop2_find_start_mixer_id_for_vp(struct vop2_video_port *vp)
>  
>  	for (i = 0; i < 31; i += 4) {
>  		match = false;
> -		for_each_set_bit(phys_id, &win_mask, ROCKCHIP_VOP2_ESMART3) {
> +		for_each_set_bit(phys_id, &win_mask, ROCKCHIP_VOP2_ESMART3 + 1) {

It would be better to add `ROCKCHIP_VOP_MAX_LAYER_ID` after ROCKCHIP_VOP2_ESMART3.

>  			win = vop2_find_win_by_phys_id(vop2, phys_id);
>  			if (win->data->layer_sel_id[vp->id] == ((layer_sel >> i) & 0xf)) {
>  				match = true;
> 

-- 
Best, 
Chaoyi

Re: [PATCH 7/8] drm/rockchip: vop2: Keep the other LUT_PORT_SEL fields on gamma LUT updates

[Chaoyi Chen]

On 11/10/2026 3:18 PM, Arun Iyengar via B4 Relay wrote:
> From: Arun Iyengar <aiyengar1990@gmail.com>
> 
> On RK3588 the gamma LUT of a video port is written through a window that
> GAMMA_AHB_WRITE_SEL in SYS_CTRL_LUT_PORT_SEL selects. The register also
> holds the dclk source selection of video ports 0 and 2 and the enable of
> the video port 0/1 merge for modes wider than 4096 pixels, which writing
> the whole register clears.
> 
> Only update the write select field.
> 
> Signed-off-by: Arun Iyengar <aiyengar1990@gmail.com>

Reviewed-by: Chaoyi Chen <chaoyi.chen@rock-chips.com>

> ---
>  drivers/gpu/drm/rockchip/rockchip_drm_vop2.c | 5 +++--
>  1 file changed, 3 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/gpu/drm/rockchip/rockchip_drm_vop2.c b/drivers/gpu/drm/rockchip/rockchip_drm_vop2.c
> index 3323e50224c5..9ad138457204 100644
> --- a/drivers/gpu/drm/rockchip/rockchip_drm_vop2.c
> +++ b/drivers/gpu/drm/rockchip/rockchip_drm_vop2.c
> @@ -1774,8 +1774,9 @@ static void vop2_crtc_atomic_set_gamma_seamless(struct vop2 *vop2,
>  						struct vop2_video_port *vp,
>  						struct drm_crtc *crtc)
>  {
> -	vop2_writel(vop2, RK3568_LUT_PORT_SEL,
> -		    FIELD_PREP(RK3588_LUT_PORT_SEL__GAMMA_AHB_WRITE_SEL, vp->id));
> +	regmap_update_bits(vop2->map, RK3568_LUT_PORT_SEL,
> +			   RK3588_LUT_PORT_SEL__GAMMA_AHB_WRITE_SEL,
> +			   FIELD_PREP(RK3588_LUT_PORT_SEL__GAMMA_AHB_WRITE_SEL, vp->id));
>  	vop2_vp_dsp_lut_enable(vp);
>  	vop2_crtc_write_gamma_lut(vop2, crtc);
>  	vop2_vp_dsp_lut_update_enable(vp);
> 

-- 
Best, 
Chaoyi

Re: [PATCH 5/8] drm/rockchip: vop2: Report POST_BUF_EMPTY at most once per frame

[Chaoyi Chen]

Hi Arun,

On 11/10/2026 3:18 PM, Arun Iyengar via B4 Relay wrote:
> From: Arun Iyengar <aiyengar1990@gmail.com>
> 
> POST_BUF_EMPTY is raised for every line on which the post processing
> stage of a video port finds no data. The interrupt handler only
> rate-limits the error message and leaves the interrupt enabled, so an
> underflowing video port keeps the CPU in the interrupt handler 50000 to
> 300000 times per second, for as long as the configuration that causes
> the underflow stays in place (e.g. 120000 interrupts per second for
> 3840x2160@120 with two full screen layers on one AXI port).
> 
> Mask POST_BUF_EMPTY when it fires and unmask it at the next frame start.
> The frame start (FS) interrupt is enabled for that frame even when
> vblank reporting is off, and disabled again once POST_BUF_EMPTY is
> re-armed. A new per video port lock serialises the interrupt enable
> bookkeeping between the interrupt handler and the vblank callbacks.
> The error is still reported, now at most once per frame and video port.
> 
> Signed-off-by: Arun Iyengar <aiyengar1990@gmail.com>
> ---
>  drivers/gpu/drm/rockchip/rockchip_drm_vop2.c | 63 ++++++++++++++++++++++++++--
>  drivers/gpu/drm/rockchip/rockchip_drm_vop2.h | 10 +++++
>  2 files changed, 70 insertions(+), 3 deletions(-)
> 
> diff --git a/drivers/gpu/drm/rockchip/rockchip_drm_vop2.c b/drivers/gpu/drm/rockchip/rockchip_drm_vop2.c
> index 9aeb90c6aa4b..3323e50224c5 100644
> --- a/drivers/gpu/drm/rockchip/rockchip_drm_vop2.c
> +++ b/drivers/gpu/drm/rockchip/rockchip_drm_vop2.c
> @@ -841,6 +841,48 @@ static void vop2_crtc_disable_irq(struct vop2_video_port *vp, u32 irq)
>  	vop2_writel(vop2, RK3568_VP_INT_EN(vp->id), irq << 16);
>  }
>  
> +/*
> + * POST_BUF_EMPTY is raised for every line the post processing stage finds
> + * no data for, so an underflowing video port can raise it 100000 times per
> + * second. Report it at most once per frame: mask it when it fires and
> + * unmask it at the next frame start, using the FS interrupt even when
> + * vblank reporting is off.
> + */
> +static void vop2_crtc_enable_post_buf_empty_irq(struct vop2_video_port *vp)
> +{
> +	unsigned long flags;
> +
> +	spin_lock_irqsave(&vp->irq_lock, flags);
> +	vp->post_buf_empty_masked = false;
> +	vop2_crtc_enable_irq(vp, VP_INT_POST_BUF_EMPTY);
> +	spin_unlock_irqrestore(&vp->irq_lock, flags);
> +}
> +
> +static void vop2_crtc_handle_post_buf_empty(struct vop2_video_port *vp)
> +{
> +	struct vop2 *vop2 = vp->vop2;
> +
> +	spin_lock(&vp->irq_lock);
> +	vop2_crtc_disable_irq(vp, VP_INT_POST_BUF_EMPTY);
> +	vp->post_buf_empty_masked = true;
> +	/* don't clear a pending FS, it may carry a vblank event */
> +	vop2_writel(vop2, RK3568_VP_INT_EN(vp->id),
> +		    VP_INT_FS_FIELD << 16 | VP_INT_FS_FIELD);

Do we really need this? Disabling the POST_BUF_EMPTY IRQ should not
affect the FS_FIELD IRQ, because this register has write mask.


> +	spin_unlock(&vp->irq_lock);
> +}
> +
> +static void vop2_crtc_rearm_post_buf_empty(struct vop2_video_port *vp)
> +{
> +	spin_lock(&vp->irq_lock);
> +	if (vp->post_buf_empty_masked) {
> +		vp->post_buf_empty_masked = false;
> +		vop2_crtc_enable_irq(vp, VP_INT_POST_BUF_EMPTY);
> +		if (!vp->vblank_enabled)
> +			vop2_crtc_disable_irq(vp, VP_INT_FS_FIELD);
> +	}
> +	spin_unlock(&vp->irq_lock);
> +}
> +
>  static int vop2_core_clks_prepare_enable(struct vop2 *vop2)
>  {
>  	int ret;
> @@ -1668,8 +1710,12 @@ static const struct drm_plane_funcs vop2_plane_funcs = {
>  static int vop2_crtc_enable_vblank(struct drm_crtc *crtc)
>  {
>  	struct vop2_video_port *vp = to_vop2_video_port(crtc);
> +	unsigned long flags;
>  
> +	spin_lock_irqsave(&vp->irq_lock, flags);
> +	vp->vblank_enabled = true;
>  	vop2_crtc_enable_irq(vp, VP_INT_FS_FIELD);
> +	spin_unlock_irqrestore(&vp->irq_lock, flags);
>  
>  	return 0;
>  }
> @@ -1677,8 +1723,13 @@ static int vop2_crtc_enable_vblank(struct drm_crtc *crtc)
>  static void vop2_crtc_disable_vblank(struct drm_crtc *crtc)
>  {
>  	struct vop2_video_port *vp = to_vop2_video_port(crtc);
> +	unsigned long flags;
>  
> -	vop2_crtc_disable_irq(vp, VP_INT_FS_FIELD);
> +	spin_lock_irqsave(&vp->irq_lock, flags);
> +	vp->vblank_enabled = false;
> +	if (!vp->post_buf_empty_masked)
> +		vop2_crtc_disable_irq(vp, VP_INT_FS_FIELD);
> +	spin_unlock_irqrestore(&vp->irq_lock, flags);
>  }
>  
>  static enum drm_mode_status vop2_crtc_mode_valid(struct drm_crtc *crtc,
> @@ -1977,7 +2028,7 @@ static void vop2_crtc_atomic_enable(struct drm_crtc *crtc,
>  
>  	vcstate->yuv_overlay = is_yuv_output(vcstate->bus_format);
>  
> -	vop2_crtc_enable_irq(vp, VP_INT_POST_BUF_EMPTY);
> +	vop2_crtc_enable_post_buf_empty_irq(vp);
>  
>  	polflags = 0;
>  	if (vcstate->bus_flags & DRM_BUS_FLAG_PIXDATA_DRIVE_NEGEDGE)
> @@ -2535,6 +2586,7 @@ static irqreturn_t rk3576_vp_isr(int irq, void *data)
>  	}
>  
>  	if (irqs & VP_INT_FS_FIELD) {
> +		vop2_crtc_rearm_post_buf_empty(vp);
>  		drm_crtc_handle_vblank(crtc);
>  		spin_lock(&crtc->dev->event_lock);
>  		if (vp->event) {
> @@ -2552,6 +2604,7 @@ static irqreturn_t rk3576_vp_isr(int irq, void *data)
>  	}
>  
>  	if (irqs & VP_INT_POST_BUF_EMPTY) {
> +		vop2_crtc_handle_post_buf_empty(vp);
>  		drm_err_ratelimited(vop2->drm, "POST_BUF_EMPTY irq err at vp%d\n", vp->id);
>  		ret = IRQ_HANDLED;
>  	}
> @@ -2591,6 +2644,7 @@ static irqreturn_t vop2_isr(int irq, void *data)
>  			}
>  
>  			if (irqs & VP_INT_FS_FIELD) {
> +				vop2_crtc_rearm_post_buf_empty(vp);
>  				drm_crtc_handle_vblank(crtc);
>  				spin_lock(&crtc->dev->event_lock);
>  				if (vp->event) {
> @@ -2608,6 +2662,7 @@ static irqreturn_t vop2_isr(int irq, void *data)
>  			}
>  
>  			if (irqs & VP_INT_POST_BUF_EMPTY) {
> +				vop2_crtc_handle_post_buf_empty(vp);
>  				drm_err_ratelimited(vop2->drm,
>  						    "POST_BUF_EMPTY irq err at vp%d\n",
>  						    vp->id);
> @@ -2984,7 +3039,7 @@ static int vop2_bind(struct device *dev, struct device *master, void *data)
>  	struct vop2 *vop2;
>  	struct resource *res;
>  	size_t alloc_size;
> -	int ret;
> +	int ret, i;
>  
>  	vop2_data = of_device_get_match_data(dev);
>  	if (!vop2_data)
> @@ -3102,6 +3157,8 @@ static int vop2_bind(struct device *dev, struct device *master, void *data)
>  	mutex_init(&vop2->vop2_lock);
>  	mutex_init(&vop2->ovl_lock);
>  	spin_lock_init(&vop2->axi_lock);
> +	for (i = 0; i < ARRAY_SIZE(vop2->vps); i++)
> +		spin_lock_init(&vop2->vps[i].irq_lock);
>  
>  	ret = devm_request_irq(dev, vop2->irq, vop2_isr, IRQF_SHARED, dev_name(dev), vop2);
>  	if (ret)
> diff --git a/drivers/gpu/drm/rockchip/rockchip_drm_vop2.h b/drivers/gpu/drm/rockchip/rockchip_drm_vop2.h
> index f1e35967e67f..7de32bef8d7b 100644
> --- a/drivers/gpu/drm/rockchip/rockchip_drm_vop2.h
> +++ b/drivers/gpu/drm/rockchip/rockchip_drm_vop2.h
> @@ -272,6 +272,16 @@ struct vop2_video_port {
>  	struct drm_pending_vblank_event *event;
>  
>  	unsigned int nlayers;
> +
> +	/** @irq_lock: protects @vblank_enabled and @post_buf_empty_masked */
> +	spinlock_t irq_lock;
> +	/** @vblank_enabled: the FS interrupt is enabled for vblank reporting */
> +	bool vblank_enabled;
> +	/**
> +	 * @post_buf_empty_masked: POST_BUF_EMPTY is masked until the next
> +	 * frame start
> +	 */
> +	bool post_buf_empty_masked;
>  };
>  
>  /**
> 

-- 
Best, 
Chaoyi