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

[Nicolas Dufresne <nicolas.dufresne@collabora.com>]

Hi Tim,

Le mercredi 05 mars 2025 à 11:41 +0100, Tim Surber a écrit :
> Hi,
> 
> so the 4:4:4 issue was just a gstreamer bug and it worked when I
> applied 
> an experimental fix [1].
> 
> So everything works for me using the default EDID now.
> 
> Tested-by: Tim Surber <me@timsurber.de>
> 
> [1]: 
> https://gitlab.freedesktop.org/gstreamer/gstreamer/-/merge_requests/8534

Thanks, I'll try and get this fix moving soon. I now have a RK3588 with
hacks that let me force YUV in the 3 subsampling, so I can easily
reproduce now.

Nicolas

p.s. I also hit some buffer starvation issues (inside GStreamer), for
which I will be sending a fix to this driver so GStreamer is aware of
the lost frames.

> 
> On 3/5/25 10:09, Dmitry Osipenko wrote:
> > On 3/5/25 12:03, Dmitry Osipenko wrote:
> > > 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.
> > 
> > BTW, I don't see it as a blocker. Driver works in general, new
> > issues
> > can be resolved with additional patches.
> > 

-- 
Nicolas Dufresne
Principal Engineer at Collabora

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