linux-kernel - Re: [PATCH v13 0/6] Add Synopsys DesignWare HDMI RX Controller

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Message-ID: <9b4b1e65-127d-422b-a359-a1d8e25652f9@xs4all.nl>
Date: Wed, 5 Mar 2025 09:10:09 +0100
From: Hans Verkuil <hverkuil@...all.nl>
To: Tim Surber <me@...surber.de>,
 Dmitry Osipenko <dmitry.osipenko@...labora.com>,
 Shreeya Patel <shreeya.patel@...labora.com>, Heiko Stuebner
 <heiko@...ech.de>, Mauro Carvalho Chehab <mchehab@...nel.org>,
 Rob Herring <robh@...nel.org>, Krzysztof Kozlowski <krzk+dt@...nel.org>,
 Conor Dooley <conor+dt@...nel.org>, jose.abreu@...opsys.com,
 nelson.costa@...opsys.com, shawn.wen@...k-chips.com,
 nicolas.dufresne@...labora.com,
 Sebastian Reichel <sebastian.reichel@...labora.com>
Cc: kernel@...labora.com, linux-media@...r.kernel.org,
 devicetree@...r.kernel.org, linux-kernel@...r.kernel.org,
 linux-rockchip@...ts.infradead.org,
 Christophe JAILLET <christophe.jaillet@...adoo.fr>,
 Diederik de Haas <didi.debian@...ow.org>
Subject: Re: [PATCH v13 0/6] Add Synopsys DesignWare HDMI RX Controller

On 05/03/2025 01:59, Tim Surber wrote:
> Hi Dmitry,
> 
> I did some more testing. That the Apple TV did not work was a bit 
> misleading.
> 
> It was just, that the Apple TV defaulted to 4:4:4 Chroma which does not 
> work at all for me. (The same happens using the vendor driver).
> 
> When I changed the EDID to match the vendor driver the HDMI handshake 
> happened with 4:2:0 chroma, where I could verify even 4k60fps using your 
> driver, nice!
> 
> So the remaining problems I see are:
> - 4:4:4 chroma not working in any resolution
> - 4:2:2 and RGB not working in 4k60fps (is this a hardware limitation?)
> 
> A possible workaround could be to disable these non supported formats in 
> the default EDID.

I would like to merge this driver this week, since otherwise it will likely
slip to v6.16. So if there is a working EDID, perhaps it can be used for now,
and later on it can be patched if there is a better EDID.

Would this EDID work? Tim, can you try this?

v4l2-ctl --set-edid type=hdmi-4k-600mhz,ycbcr444,ycbcr422

Alternatively, if there is indeed a HW limitation that prevents 4kp60 to work,
try this:

v4l2-ctl --set-edid type=hdmi-4k-300mhz,ycbcr444,ycbcr422

Whichever of the two works is what we can use as default EDID.

Regards,

	Hans