Re: drm/bridge: dw-hdmi-qp: seamless handoff sets wrong tmds_char_rate, breaking audio on strict HDMI 2.1 sinks

[Cristian Ciocaltea <cristian.ciocaltea@collabora.com>]

Hi Simon,

On 5/8/26 8:53 AM, Simon Wright wrote:
> Hi Cristian,
> 
> Thanks for the pointers -- I should have checked rockchip-devel
> before the previous reply. Three things to clean up:
> 
> * Sige5 in linux-next and Sige7 in rockchip-devel both match what I'd
>   derived from the schematics -- dropping the DTS follow-ups I had
>   drafted.
> 
> * Your FRL work in rockchip-devel supersedes the BSP-derived prototype
>   I was going to port. Standing down on that; happy to Tested-by the
>   series once it's posted.
> 
> * Acknowledged on the HDMI 1.4 vs 2.x framing.
> 
> Tested-by: Simon Wright <simon@symple.nz>

The trailer must be added by replying to the series containing the patches, i.e.
see the "Reply instructions" at the bottom of:

  https://lore.kernel.org/all/20260227-hdptx-clk-fixes-v1-0-f998f2762d0f@collabora.com/

> 
> Heiko, Vinod -- any chance hdptx-clk-fixes v1 can be applied? It
> cleanly addresses the high-bpc rate recalculation and uncommitted PHY
> config issues on RK3576 hdptx, and Tested-by results on real hardware
> (R76S + LG G3 OLED) match the cover letter.

This should also go with the reply above.

> 
> Reproducer for the audio mute:
> 
>   1. mainline 7.0 + hdptx-clk-fixes v1 applied (or rockchip-devel HEAD
>      -- same code path).
>   2. Sink that doesn't tolerate incorrect ACR CTS values -- LG G3 OLED
>      is the canonical case, LG C4 OLED behaves identically. More-
>      permissive sinks play audio regardless and won't surface the bug.
>   3. Set a mode whose tmds_char_rate is NOT in common_tmds_cts_table[].
>      Affected rates we tested: 1920x1080@60 bpc=10 (185.625 MHz, the
>      original-bug regime -- requires max_bpc=10 set on the connector
>      property), 3840x2160@30 8-bit (297 MHz), and 3840x2160@60 8-bit
>      (594 MHz).
>   4. The mode must be held for the duration of the audio test --
>      `modetest -s` releases DRM master on exit and fbcon reverts to
>      an in-table mode, which would explain audio playing in your
>      test path.
>   5. speaker-test -D hw:0,0 -c 2 -t sine -f 440 -- mutes without the
>      fix, plays with it.
> 
> I'll send the CTS-from-N change as a separate patch against
> rockchip-devel, 

Any submitted patches must be based on a recent enough upstream branch or tag -
in this case either v7.1-rc2 [1], next-20260507 [2] or drm-misc-next [3].

[1] https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?h=v7.1-rc2
[2] https://git.kernel.org/pub/scm/linux/kernel/git/next/linux-next.git/tag/?h=next-20260507
[3] https://gitlab.freedesktop.org/drm/misc/kernel/-/commits/drm-misc-next?ref_type=heads

Regards,
Cristian

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