[PATCH 23/33] drm/vc4: hdmi: Move HDMI reset to pm_resume

[Stefan Wahren]

Hi Florian,

Am 09.08.22 um 21:02 schrieb Florian Fainelli:
> On 8/4/22 16:11, Florian Fainelli wrote:
>> On 6/13/22 07:47, Maxime Ripard wrote:
>>> From: Dave Stevenson <dave.stevenson at raspberrypi.com>
>>>
>>> The BCM2835-37 found in the RaspberryPi 0 to 3 have a power domain
>>> attached to the HDMI block, handled in Linux through runtime_pm.
>>>
>>> That power domain is shared with the VEC block, so even if we put our
>>> runtime_pm reference in the HDMI driver it would keep being on. If the
>>> VEC is disabled though, the power domain would be disabled and we would
>>> lose any initialization done in our bind implementation.
>>>
>>> That initialization involves calling the reset function and 
>>> initializing
>>> the CEC registers.
>>>
>>> Let's move the initialization to our runtime_resume implementation so
>>> that we initialize everything properly if we ever need to.
>>>
>>> Fixes: c86b41214362 ("drm/vc4: hdmi: Move the HSM clock enable to 
>>> runtime_pm")
>>> Signed-off-by: Dave Stevenson <dave.stevenson at raspberrypi.com>
>>> Signed-off-by: Maxime Ripard <maxime at cerno.tech>
>>
>> After seeing the same warning as Stefan reported in the link below, 
>> but on the Raspberry Pi 4B:
>>
>> https://www.spinics.net/lists/dri-devel/msg354170.html
>>
>> a separate bisection effort led me to this commit, before is fine, 
>> after produces 4 warnings during boot, see attached log.
>>
>> Is there a fix that we can try that would also cover the Raspberry Pi 
>> 4B? Is it possible that this series precipitates the problem:
>>
>> https://www.spinics.net/lists/arm-kernel/msg984638.html
>
> Maxime, Dave, anything you would want me to try? Still seeing these 
> warnings with net-next-6.0-11220-g15205c2829ca

At first this issue doesn't occur in Linux 5.19. So it's something new. 
I was able to reproduce with todays linux-next, but interestingly it 
doesn't occur in drm-misc-next.

>
> Would be nice to see those fixes before 6.0 final, thanks!