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

[Maxime Ripard]

On Wed, Aug 10, 2022 at 10:33:48PM +0200, Stefan Wahren wrote:
> 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.

Yeah, it should be fixed by
https://lore.kernel.org/all/20220629123510.1915022-38-maxime@cerno.tech/
https://lore.kernel.org/all/20220629123510.1915022-39-maxime@cerno.tech/

Both patches apparently didn't make the cut for the merge window, if it
works for you we can always queue them in drm-misc-fixes

Maxime
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