linux-kernel - Re: [PATCH 2/2] media: qcom: camss: Fix ordering of pm_runtime

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Message-ID: <ZpTTxk_7hBbFLTTp@hovoldconsulting.com>
Date: Mon, 15 Jul 2024 09:46:14 +0200
From: Johan Hovold <johan@...nel.org>
To: Bryan O'Donoghue <bryan.odonoghue@...aro.org>
Cc: Robert Foss <rfoss@...nel.org>, Todor Tomov <todor.too@...il.com>,
	Mauro Carvalho Chehab <mchehab@...nel.org>,
	Hans Verkuil <hansverk@...co.com>,
	Hans Verkuil <hverkuil-cisco@...all.nl>,
	Milen Mitkov <quic_mmitkov@...cinc.com>,
	linux-media@...r.kernel.org, linux-arm-msm@...r.kernel.org,
	linux-kernel@...r.kernel.org,
	Mauro Carvalho Chehab <mchehab+samsung@...nel.org>,
	Johan Hovold <johan+linaro@...nel.org>
Subject: Re: [PATCH 2/2] media: qcom: camss: Fix ordering of pm_runtime_enable

On Sun, Jul 14, 2024 at 11:53:59PM +0100, Bryan O'Donoghue wrote:
> pm_runtime_enable() should happen prior to vfe_get() since vfe_get() calls
> pm_runtime_resume_and_get().

Again, please describe how this manifest itself to users. I see
occasional:

	qcom-camss ac5a000.camss: Failed to power up pipeline: -13

on boot.

> This is a basic race condition that doesn't show up for most users so is
> not widely reported. If you blacklist qcom-camss in modules.d and then
> subsequently modprobe the module post-boot it is possible to reliably show
> this error up.
> 
> Fixes: 02afa816dbbf ("media: camss: Add basic runtime PM support")

Missing CC-stable here too.

> Signed-off-by: Bryan O'Donoghue <bryan.odonoghue@...aro.org>

Reported-by: Johan Hovold <johan+linaro@...nel.org>
Link: https://lore.kernel.org/lkml/ZoVNHOTI0PKMNt4_@hovoldconsulting.com/
Tested-by: Johan Hovold <johan+linaro@...nel.org>

Johan