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

[Dmitry Osipenko]

On 3/5/25 11:10, Hans Verkuil wrote:
> 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.

Disabling 444 and 422 is an option. Though, they work on my setup at
4k@60p.

In general, it often a challenge to get 4k@60p properly with any of
these small board devices. 4k@60p works only using a short HDMI cable
for me. Also, not everyone aware that the micro HDMI adapter needs to be
compliant with HDMI 2.0 for 4k@60, that's why 300MHz is the default.

Will be nice to have the good EDID enabled by default in the defconfig.
Dealing with problems like that will be a headache for majority of
people, IMO.

-- 
Best regards,
Dmitry