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

[Chaoyi Chen <chaoyi.chen@rock-chips.com>]

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