[PATCH 0/2] drm/rockchip: dw_hdmi_qp: Add support for HDMI overscan compensation

[PATCH 0/2] drm/rockchip: dw_hdmi_qp: Add support for HDMI overscan compensation

[Alexey Charkov]

When using a TV as a display, output image may be cropped due to overscan.
Rockchip VOP2 supports post-composition scaling in hardware, which can be
used to compensate for the overscan.

This adds the necessary pixel margin fields to the CRTC state, and sets
them from the TV overscan property of the connector which is understood
by the userspace (tested with KWin's display configuration module).

Signed-off-by: Alexey Charkov <alchark@flipper.net>
---
Alexey Charkov (2):
      drm/rockchip: vop2: honor TV margins from CRTC state for overscan compensation
      drm/rockchip: dw_hdmi_qp: expose "overscan" property

 drivers/gpu/drm/rockchip/dw_hdmi_qp-rockchip.c | 16 ++++++++++++++++
 drivers/gpu/drm/rockchip/rockchip_drm_drv.h    |  2 ++
 drivers/gpu/drm/rockchip/rockchip_drm_vop2.c   | 17 +++++++++++------
 3 files changed, 29 insertions(+), 6 deletions(-)
---
base-commit: 08484c504b55a98bd100527fbe10a3caf55ff3ff
change-id: 20260602-hdmi-overscan-4f0d89bfd981

Best regards,
-- 
Alexey Charkov <alchark@flipper.net>

[PATCH 1/2] drm/rockchip: vop2: honor TV margins from CRTC state for overscan compensation

[Alexey Charkov]

Replace the hard-coded percent values with pixel margins carried in struct
rockchip_crtc_state, sourced from the standard DRM "left/right/top/bottom
margin" connector properties (struct drm_connector_tv_margins) to pave way
for HDMI overscan compensation support.

Signed-off-by: Alexey Charkov <alchark@flipper.net>
---
 drivers/gpu/drm/rockchip/rockchip_drm_drv.h  |  2 ++
 drivers/gpu/drm/rockchip/rockchip_drm_vop2.c | 17 +++++++++++------
 2 files changed, 13 insertions(+), 6 deletions(-)

diff --git a/drivers/gpu/drm/rockchip/rockchip_drm_drv.h b/drivers/gpu/drm/rockchip/rockchip_drm_drv.h
index 2e86ad00979c..83f8ec4f3319 100644
--- a/drivers/gpu/drm/rockchip/rockchip_drm_drv.h
+++ b/drivers/gpu/drm/rockchip/rockchip_drm_drv.h
@@ -10,6 +10,7 @@
 #define _ROCKCHIP_DRM_DRV_H
 
 #include <drm/drm_atomic_helper.h>
+#include <drm/drm_connector.h>
 #include <drm/drm_gem.h>
 
 #include <linux/bits.h>
@@ -53,6 +54,7 @@ struct rockchip_crtc_state {
 	u32 bus_format;
 	u32 bus_flags;
 	int color_space;
+	struct drm_connector_tv_margins tv_margins;
 };
 #define to_rockchip_crtc_state(s) \
 		container_of(s, struct rockchip_crtc_state, base)
diff --git a/drivers/gpu/drm/rockchip/rockchip_drm_vop2.c b/drivers/gpu/drm/rockchip/rockchip_drm_vop2.c
index a160077a507f..55307b8493ae 100644
--- a/drivers/gpu/drm/rockchip/rockchip_drm_vop2.c
+++ b/drivers/gpu/drm/rockchip/rockchip_drm_vop2.c
@@ -1558,30 +1558,35 @@ static void vop2_post_config(struct drm_crtc *crtc)
 {
 	struct vop2_video_port *vp = to_vop2_video_port(crtc);
 	struct vop2 *vop2 = vp->vop2;
+	struct rockchip_crtc_state *vcstate = to_rockchip_crtc_state(crtc->state);
 	struct drm_display_mode *mode = &crtc->state->adjusted_mode;
+	const struct drm_connector_tv_margins *m = &vcstate->tv_margins;
 	u64 bgcolor = crtc->state->background_color;
 	u16 vtotal = mode->crtc_vtotal;
 	u16 hdisplay = mode->crtc_hdisplay;
 	u16 hact_st = mode->crtc_htotal - mode->crtc_hsync_start;
 	u16 vdisplay = mode->crtc_vdisplay;
 	u16 vact_st = mode->crtc_vtotal - mode->crtc_vsync_start;
-	u32 left_margin = 100, right_margin = 100;
-	u32 top_margin = 100, bottom_margin = 100;
-	u16 hsize = hdisplay * (left_margin + right_margin) / 200;
-	u16 vsize = vdisplay * (top_margin + bottom_margin) / 200;
+	u16 hsize = hdisplay;
+	u16 vsize = vdisplay;
 	u16 hact_end, vact_end;
 	u32 val;
 
 	vop2->ops->setup_bg_dly(vp);
 
+	if (m->left + m->right < hdisplay)
+		hsize = hdisplay - m->left - m->right;
+	if (m->top + m->bottom < vdisplay)
+		vsize = vdisplay - m->top - m->bottom;
+
 	vsize = rounddown(vsize, 2);
 	hsize = rounddown(hsize, 2);
-	hact_st += hdisplay * (100 - left_margin) / 200;
+	hact_st += m->left;
 	hact_end = hact_st + hsize;
 	val = hact_st << 16;
 	val |= hact_end;
 	vop2_vp_write(vp, RK3568_VP_POST_DSP_HACT_INFO, val);
-	vact_st += vdisplay * (100 - top_margin) / 200;
+	vact_st += m->top;
 	vact_end = vact_st + vsize;
 	val = vact_st << 16;
 	val |= vact_end;

-- 
2.52.0

[PATCH 2/2] drm/rockchip: dw_hdmi_qp: expose "overscan" property

[Alexey Charkov]

Expose the "overscan" connector property as recognized by KWin and the
likes to compensate for TV overscan cropping.

The CRTC will use the margin values derived from this overscan percentage
in its post-composition scaler to add appropriate blank margins on all
sides of the output image so that the TV doesn't eat up visible content.

Signed-off-by: Alexey Charkov <alchark@flipper.net>
---
 drivers/gpu/drm/rockchip/dw_hdmi_qp-rockchip.c | 16 ++++++++++++++++
 1 file changed, 16 insertions(+)

diff --git a/drivers/gpu/drm/rockchip/dw_hdmi_qp-rockchip.c b/drivers/gpu/drm/rockchip/dw_hdmi_qp-rockchip.c
index f35484715c2d..fae44d11dbef 100644
--- a/drivers/gpu/drm/rockchip/dw_hdmi_qp-rockchip.c
+++ b/drivers/gpu/drm/rockchip/dw_hdmi_qp-rockchip.c
@@ -137,10 +137,18 @@ dw_hdmi_qp_rockchip_encoder_atomic_check(struct drm_encoder *encoder,
 					 struct drm_connector_state *conn_state)
 {
 	struct rockchip_hdmi_qp *hdmi = to_rockchip_hdmi_qp(encoder);
+	const struct drm_display_mode *adj_mode = &crtc_state->adjusted_mode;
 	struct rockchip_crtc_state *s = to_rockchip_crtc_state(crtc_state);
 	union phy_configure_opts phy_cfg = {};
+	unsigned int overscan;
 	int ret;
 
+	overscan = min(conn_state->tv.overscan, 100u);
+	s->tv_margins.left   = adj_mode->hdisplay * overscan / 200;
+	s->tv_margins.right  = s->tv_margins.left;
+	s->tv_margins.top    = adj_mode->vdisplay * overscan / 200;
+	s->tv_margins.bottom = s->tv_margins.top;
+
 	if (hdmi->tmds_char_rate == conn_state->hdmi.tmds_char_rate &&
 	    s->output_bpc == conn_state->hdmi.output_bpc)
 		return 0;
@@ -603,6 +611,14 @@ static int dw_hdmi_qp_rockchip_bind(struct device *dev, struct device *master,
 		return dev_err_probe(hdmi->dev, PTR_ERR(connector),
 				     "Failed to init bridge connector\n");
 
+	ret = drm_mode_create_tv_properties_legacy(drm, 0, NULL);
+	if (ret)
+		return dev_err_probe(dev, ret,
+				     "Failed to create TV connector properties\n");
+
+	drm_object_attach_property(&connector->base,
+				   drm->mode_config.tv_overscan_property, 0);
+
 	return 0;
 }
 

-- 
2.52.0

Re: [PATCH 2/2] drm/rockchip: dw_hdmi_qp: expose "overscan" property

[Maxime Ripard]

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On Tue, Jun 02, 2026 at 09:00:40PM +0400, Alexey Charkov wrote:
> Expose the "overscan" connector property as recognized by KWin and the
> likes to compensate for TV overscan cropping.
> 
> The CRTC will use the margin values derived from this overscan percentage
> in its post-composition scaler to add appropriate blank margins on all
> sides of the output image so that the TV doesn't eat up visible content.
> 
> Signed-off-by: Alexey Charkov <alchark@flipper.net>
> ---
>  drivers/gpu/drm/rockchip/dw_hdmi_qp-rockchip.c | 16 ++++++++++++++++
>  1 file changed, 16 insertions(+)
> 
> diff --git a/drivers/gpu/drm/rockchip/dw_hdmi_qp-rockchip.c b/drivers/gpu/drm/rockchip/dw_hdmi_qp-rockchip.c
> index f35484715c2d..fae44d11dbef 100644
> --- a/drivers/gpu/drm/rockchip/dw_hdmi_qp-rockchip.c
> +++ b/drivers/gpu/drm/rockchip/dw_hdmi_qp-rockchip.c
> @@ -137,10 +137,18 @@ dw_hdmi_qp_rockchip_encoder_atomic_check(struct drm_encoder *encoder,
>  					 struct drm_connector_state *conn_state)
>  {
>  	struct rockchip_hdmi_qp *hdmi = to_rockchip_hdmi_qp(encoder);
> +	const struct drm_display_mode *adj_mode = &crtc_state->adjusted_mode;
>  	struct rockchip_crtc_state *s = to_rockchip_crtc_state(crtc_state);
>  	union phy_configure_opts phy_cfg = {};
> +	unsigned int overscan;
>  	int ret;
>  
> +	overscan = min(conn_state->tv.overscan, 100u);
> +	s->tv_margins.left   = adj_mode->hdisplay * overscan / 200;
> +	s->tv_margins.right  = s->tv_margins.left;
> +	s->tv_margins.top    = adj_mode->vdisplay * overscan / 200;
> +	s->tv_margins.bottom = s->tv_margins.top;
> +
>  	if (hdmi->tmds_char_rate == conn_state->hdmi.tmds_char_rate &&
>  	    s->output_bpc == conn_state->hdmi.output_bpc)
>  		return 0;
> @@ -603,6 +611,14 @@ static int dw_hdmi_qp_rockchip_bind(struct device *dev, struct device *master,
>  		return dev_err_probe(hdmi->dev, PTR_ERR(connector),
>  				     "Failed to init bridge connector\n");
>  
> +	ret = drm_mode_create_tv_properties_legacy(drm, 0, NULL);
> +	if (ret)
> +		return dev_err_probe(dev, ret,
> +				     "Failed to create TV connector properties\n");
> +
> +	drm_object_attach_property(&connector->base,
> +				   drm->mode_config.tv_overscan_property, 0);
> +

As the name suggests, it's a legacy property only ever used for TV. You
should be using drm_mode_create_tv_margin_properties()

Maxime

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Re: [PATCH 2/2] drm/rockchip: dw_hdmi_qp: expose "overscan" property

[Alexey Charkov]

On Wed, Jun 3, 2026 at 11:55 AM Maxime Ripard <mripard@kernel.org> wrote:
>
> On Tue, Jun 02, 2026 at 09:00:40PM +0400, Alexey Charkov wrote:
> > Expose the "overscan" connector property as recognized by KWin and the
> > likes to compensate for TV overscan cropping.
> >
> > The CRTC will use the margin values derived from this overscan percentage
> > in its post-composition scaler to add appropriate blank margins on all
> > sides of the output image so that the TV doesn't eat up visible content.
> >
> > Signed-off-by: Alexey Charkov <alchark@flipper.net>
> > ---
> >  drivers/gpu/drm/rockchip/dw_hdmi_qp-rockchip.c | 16 ++++++++++++++++
> >  1 file changed, 16 insertions(+)
> >
> > diff --git a/drivers/gpu/drm/rockchip/dw_hdmi_qp-rockchip.c b/drivers/gpu/drm/rockchip/dw_hdmi_qp-rockchip.c
> > index f35484715c2d..fae44d11dbef 100644
> > --- a/drivers/gpu/drm/rockchip/dw_hdmi_qp-rockchip.c
> > +++ b/drivers/gpu/drm/rockchip/dw_hdmi_qp-rockchip.c
> > @@ -137,10 +137,18 @@ dw_hdmi_qp_rockchip_encoder_atomic_check(struct drm_encoder *encoder,
> >                                        struct drm_connector_state *conn_state)
> >  {
> >       struct rockchip_hdmi_qp *hdmi = to_rockchip_hdmi_qp(encoder);
> > +     const struct drm_display_mode *adj_mode = &crtc_state->adjusted_mode;
> >       struct rockchip_crtc_state *s = to_rockchip_crtc_state(crtc_state);
> >       union phy_configure_opts phy_cfg = {};
> > +     unsigned int overscan;
> >       int ret;
> >
> > +     overscan = min(conn_state->tv.overscan, 100u);
> > +     s->tv_margins.left   = adj_mode->hdisplay * overscan / 200;
> > +     s->tv_margins.right  = s->tv_margins.left;
> > +     s->tv_margins.top    = adj_mode->vdisplay * overscan / 200;
> > +     s->tv_margins.bottom = s->tv_margins.top;
> > +
> >       if (hdmi->tmds_char_rate == conn_state->hdmi.tmds_char_rate &&
> >           s->output_bpc == conn_state->hdmi.output_bpc)
> >               return 0;
> > @@ -603,6 +611,14 @@ static int dw_hdmi_qp_rockchip_bind(struct device *dev, struct device *master,
> >               return dev_err_probe(hdmi->dev, PTR_ERR(connector),
> >                                    "Failed to init bridge connector\n");
> >
> > +     ret = drm_mode_create_tv_properties_legacy(drm, 0, NULL);
> > +     if (ret)
> > +             return dev_err_probe(dev, ret,
> > +                                  "Failed to create TV connector properties\n");
> > +
> > +     drm_object_attach_property(&connector->base,
> > +                                drm->mode_config.tv_overscan_property, 0);
> > +
>
> As the name suggests, it's a legacy property only ever used for TV. You
> should be using drm_mode_create_tv_margin_properties()

Hi Maxime, I tried that one before going for the current solution but
realized that the userspace tooling I care about (KWin in particular)
doesn't recognize those properties, but it does recognize "overscan".
Maybe there's a compat helper somewhere that I missed, which would
translate between the two?

It is for TVs. Turns out that having a proper right-sized digital
input interface doesn't prevent them from doing weird stuff with the
image data, i.e. overscanning and cropping it right where one would
expect to see the system tray and panel.

Best regards,
Alexey

Re: [PATCH 2/2] drm/rockchip: dw_hdmi_qp: expose "overscan" property

[Maxime Ripard]

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Hi Alexey,

On Wed, Jun 03, 2026 at 12:15:04PM +0400, Alexey Charkov wrote:
> On Wed, Jun 3, 2026 at 11:55 AM Maxime Ripard <mripard@kernel.org> wrote:
> >
> > On Tue, Jun 02, 2026 at 09:00:40PM +0400, Alexey Charkov wrote:
> > > Expose the "overscan" connector property as recognized by KWin and the
> > > likes to compensate for TV overscan cropping.
> > >
> > > The CRTC will use the margin values derived from this overscan percentage
> > > in its post-composition scaler to add appropriate blank margins on all
> > > sides of the output image so that the TV doesn't eat up visible content.
> > >
> > > Signed-off-by: Alexey Charkov <alchark@flipper.net>
> > > ---
> > >  drivers/gpu/drm/rockchip/dw_hdmi_qp-rockchip.c | 16 ++++++++++++++++
> > >  1 file changed, 16 insertions(+)
> > >
> > > diff --git a/drivers/gpu/drm/rockchip/dw_hdmi_qp-rockchip.c b/drivers/gpu/drm/rockchip/dw_hdmi_qp-rockchip.c
> > > index f35484715c2d..fae44d11dbef 100644
> > > --- a/drivers/gpu/drm/rockchip/dw_hdmi_qp-rockchip.c
> > > +++ b/drivers/gpu/drm/rockchip/dw_hdmi_qp-rockchip.c
> > > @@ -137,10 +137,18 @@ dw_hdmi_qp_rockchip_encoder_atomic_check(struct drm_encoder *encoder,
> > >                                        struct drm_connector_state *conn_state)
> > >  {
> > >       struct rockchip_hdmi_qp *hdmi = to_rockchip_hdmi_qp(encoder);
> > > +     const struct drm_display_mode *adj_mode = &crtc_state->adjusted_mode;
> > >       struct rockchip_crtc_state *s = to_rockchip_crtc_state(crtc_state);
> > >       union phy_configure_opts phy_cfg = {};
> > > +     unsigned int overscan;
> > >       int ret;
> > >
> > > +     overscan = min(conn_state->tv.overscan, 100u);
> > > +     s->tv_margins.left   = adj_mode->hdisplay * overscan / 200;
> > > +     s->tv_margins.right  = s->tv_margins.left;
> > > +     s->tv_margins.top    = adj_mode->vdisplay * overscan / 200;
> > > +     s->tv_margins.bottom = s->tv_margins.top;
> > > +
> > >       if (hdmi->tmds_char_rate == conn_state->hdmi.tmds_char_rate &&
> > >           s->output_bpc == conn_state->hdmi.output_bpc)
> > >               return 0;
> > > @@ -603,6 +611,14 @@ static int dw_hdmi_qp_rockchip_bind(struct device *dev, struct device *master,
> > >               return dev_err_probe(hdmi->dev, PTR_ERR(connector),
> > >                                    "Failed to init bridge connector\n");
> > >
> > > +     ret = drm_mode_create_tv_properties_legacy(drm, 0, NULL);
> > > +     if (ret)
> > > +             return dev_err_probe(dev, ret,
> > > +                                  "Failed to create TV connector properties\n");
> > > +
> > > +     drm_object_attach_property(&connector->base,
> > > +                                drm->mode_config.tv_overscan_property, 0);
> > > +
> >
> > As the name suggests, it's a legacy property only ever used for TV. You
> > should be using drm_mode_create_tv_margin_properties()
> 
> Hi Maxime, I tried that one before going for the current solution but
> realized that the userspace tooling I care about (KWin in particular)
> doesn't recognize those properties, but it does recognize "overscan".
> Maybe there's a compat helper somewhere that I missed, which would
> translate between the two?
> 
> It is for TVs. Turns out that having a proper right-sized digital
> input interface doesn't prevent them from doing weird stuff with the
> image data, i.e. overscanning and cropping it right where one would
> expect to see the system tray and panel.

When I said "TV", I meant old-school analog TV, not modern HDMI ones :)

I guess it's a Kwin issue then. To my knowledge, there's 0 HDMI driver
implementing the legacy tv properties, when VC4 implements the margin
ones for HDMI.

Maxime

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Re:[PATCH 2/2] drm/rockchip: dw_hdmi_qp: expose "overscan" property

[Andy Yan]

Hello Alexy，

At 2026-06-03 01:00:40, "Alexey Charkov" <alchark@flipper.net> wrote:
>Expose the "overscan" connector property as recognized by KWin and the
>likes to compensate for TV overscan cropping.
>
>The CRTC will use the margin values derived from this overscan percentage
>in its post-composition scaler to add appropriate blank margins on all
>sides of the output image so that the TV doesn't eat up visible content.
>
>Signed-off-by: Alexey Charkov <alchark@flipper.net>
>---
> drivers/gpu/drm/rockchip/dw_hdmi_qp-rockchip.c | 16 ++++++++++++++++
> 1 file changed, 16 insertions(+)
>
>diff --git a/drivers/gpu/drm/rockchip/dw_hdmi_qp-rockchip.c b/drivers/gpu/drm/rockchip/dw_hdmi_qp-rockchip.c
>index f35484715c2d..fae44d11dbef 100644
>--- a/drivers/gpu/drm/rockchip/dw_hdmi_qp-rockchip.c
>+++ b/drivers/gpu/drm/rockchip/dw_hdmi_qp-rockchip.c
>@@ -137,10 +137,18 @@ dw_hdmi_qp_rockchip_encoder_atomic_check(struct drm_encoder *encoder,
> 					 struct drm_connector_state *conn_state)
> {
> 	struct rockchip_hdmi_qp *hdmi = to_rockchip_hdmi_qp(encoder);
>+	const struct drm_display_mode *adj_mode = &crtc_state->adjusted_mode;
> 	struct rockchip_crtc_state *s = to_rockchip_crtc_state(crtc_state);
> 	union phy_configure_opts phy_cfg = {};
>+	unsigned int overscan;
> 	int ret;
> 
>+	overscan = min(conn_state->tv.overscan, 100u);
>+	s->tv_margins.left   = adj_mode->hdisplay * overscan / 200;
>+	s->tv_margins.right  = s->tv_margins.left;
>+	s->tv_margins.top    = adj_mode->vdisplay * overscan / 200;
>+	s->tv_margins.bottom = s->tv_margins.top;
>+
> 	if (hdmi->tmds_char_rate == conn_state->hdmi.tmds_char_rate &&
> 	    s->output_bpc == conn_state->hdmi.output_bpc)
> 		return 0;
>@@ -603,6 +611,14 @@ static int dw_hdmi_qp_rockchip_bind(struct device *dev, struct device *master,
> 		return dev_err_probe(hdmi->dev, PTR_ERR(connector),
> 				     "Failed to init bridge connector\n");
> 
>+	ret = drm_mode_create_tv_properties_legacy(drm, 0, NULL);
>+	if (ret)
>+		return dev_err_probe(dev, ret,
>+				     "Failed to create TV connector properties\n");

      I suggest calling a similar API within rockchip_drm_bind, and then attaching this property in
the connector drivers that need to expose it. This approach avoids invoking the API multiple times in multiple drivers。

>+
>+	drm_object_attach_property(&connector->base,
>+				   drm->mode_config.tv_overscan_property, 0);
>+
> 	return 0;
> }
> 
>
>-- 
>2.52.0
>
>
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