Re: [PATCH v3 00/14] Support 10-bit YUV422 and 8/10-bit YUV420 color format on DW HDMI QP

[Igor Paunovic <royalnet026@gmail.com>]

Hi Cristian,

I tested this series on an RK3588 (Orange Pi 5 Plus) with a sink that
actually needs it: a Sony TV with a 256-byte HDMI 1.4 EDID -- max TMDS
clock 300 MHz, no HF-VSDB and no SCDC, and 4K above 30 Hz offered only
through the YCbCr 4:2:0 Video Data Block (VIC 96/97/101/102). Without
YUV420 output this display has had no 4K mode above 30 Hz on the
Rockchip HDMI path.

Base: drm-misc-next dc2f9f7fed1a ("drm/komeda: Set display/writeback
clone masks"), with the dw-dp v11 and usbdp v13 series applied, plus
three local patches: board DT changes enabling USB-C DP Alt Mode and
pinning the VP2 dclk to V0PLL (DisplayPort side only; HDMI ran on VP0
from the HDMI PHY PLL), and CLOCK_ALLOW_WRITE_DEBUGFS for unrelated
clock experiments. On top of that, the samsung-hdptx clock fixes v6
[1] as the runtime dependency noted in your cover letter, then this
series.

Results on the HDMI-A-1 connector:

- The connector now lists 3840x2160 at 60/59.94/50 and 4096x2160 at
  60/50 for the first time on this setup, and 3840x2160@60 shows a
  stable picture.

- The negotiated wire format matches expectations
  (/sys/kernel/debug/dri/0/state):

    output_format=YUV 4:2:0
    output_bpc=8
    tmds_char_rate=297000000

  and clk_summary agrees: clk_hdmiphy_pixel0 = dclk_vop0 = 297 MHz,
  just under the sink's 300 MHz ceiling.

- Cycling 60 -> 30 -> 60 -> 50 -> 60 re-synced cleanly every time,
  with no errors in the kernel log and the VOP interrupt rate at the
  expected per-frame values throughout (no underrun storms).

To be explicit about the scope, three things were not covered: 10-bit
output in either format (this sink's 300 MHz TMDS limit rules out
10-bit 4:2:0 at 4K, and my compositor cannot force an output format
to exercise 10-bit 4:2:2 -- I can retest with modetest from a console
if that would be useful), and the 4096-wide modes were only verified
in the mode list.

For the series as tested above:

Tested-by: Igor Paunovic <royalnet026@gmail.com>

[1] https://lore.kernel.org/all/20260811-hdptx-clk-fixes-v6-0-75bca0ee5753@collabora.com/

Thanks,
Igor