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

From: Florian Fainelli <f.fainelli@gmail.com>
To: Stefan Wahren <stefan.wahren@i2se.com>,
	Maxime Ripard <maxime@cerno.tech>,
	Daniel Vetter <daniel.vetter@intel.com>,
	David Airlie <airlied@linux.ie>,
	Maarten Lankhorst <maarten.lankhorst@linux.intel.com>,
	Thomas Zimmermann <tzimmermann@suse.de>,
	Dave Stevenson <dave.stevenson@raspberrypi.com>
Cc: dri-devel@lists.freedesktop.org
Subject: Re: [PATCH 23/33] drm/vc4: hdmi: Move HDMI reset to pm_resume
Date: Tue, 9 Aug 2022 13:28:43 -0700	[thread overview]
Message-ID: <01b9847a-d418-ac7c-4c75-606b7ec8ffae@gmail.com> (raw)
In-Reply-To: <0692c98b-0776-0878-56eb-3c876ea98eb8@i2se.com>

Hallo Stefan,

On 8/9/22 13:16, Stefan Wahren wrote:
> Hi Florian,
> 
> Am 05.08.22 um 01:11 schrieb Florian Fainelli:
>> 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.
> Which config do you use (multi_v7_defconfig + LPAE or arm64/defconfig)?

This was actually bcm2835_defconfig copied over to arch/arm64/configs/ 
and slightly modified to enable PCIe, here is it:

https://gist.github.com/481999edc11b823d0c3e87ecf1693d26

>>
>> 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
> 
> I don't think this is related because this is a different driver.
> 
> Best regards
> 

-- 
Florian