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

From: Maxime Ripard <maxime@cerno.tech>
To: Florian Fainelli <f.fainelli@gmail.com>
Cc: Stefan Wahren <stefan.wahren@i2se.com>,
	Dave Stevenson <dave.stevenson@raspberrypi.com>,
	David Airlie <airlied@linux.ie>,
	dri-devel@lists.freedesktop.org,
	Thomas Zimmermann <tzimmermann@suse.de>,
	Daniel Vetter <daniel.vetter@intel.com>
Subject: Re: [PATCH 23/33] drm/vc4: hdmi: Move HDMI reset to pm_resume
Date: Thu, 18 Aug 2022 17:38:33 +0200	[thread overview]
Message-ID: <20220818153833.ppx2uc7ccqykuwga@houat> (raw)
In-Reply-To: <129cc9c4-b99f-cff4-bd16-093441e39a66@gmail.com>

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On Mon, Aug 15, 2022 at 09:52:59AM -0700, Florian Fainelli wrote:
> On 8/15/22 07:12, Maxime Ripard wrote:
> > 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@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@raspberrypi.com>
> > > > > > Signed-off-by: Maxime Ripard <maxime@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
> 
> Both of these patches eliminate the warning, I don't have a good set-up yet
> for ensuring that HDMI/V3dD is functional however:
> 
> Tested-by: Florian Fainelli <f.fainelli@gmail.com>

I ended up applying it today (without your Tested-by, since it was partial though)

Maxime

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