linux-kernel - Re: [PATCH v1 1/6] drm/lima: fix devfreq refcount imbalance for job timeouts

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Message-ID: <CAK4VdL2PnWTZ+M2eQqF22+VuF-YGKb_WjG=168BcuBDqD8+9kA@mail.gmail.com>
Date: Thu, 18 Jan 2024 12:14:15 +0100
From: Erico Nunes <nunes.erico@...il.com>
To: Qiang Yu <yuq825@...il.com>
Cc: dri-devel@...ts.freedesktop.org, lima@...ts.freedesktop.org, 
	anarsoul@...il.com, Maarten Lankhorst <maarten.lankhorst@...ux.intel.com>, 
	Maxime Ripard <mripard@...nel.org>, Thomas Zimmermann <tzimmermann@...e.de>, 
	David Airlie <airlied@...il.com>, Daniel Vetter <daniel@...ll.ch>, 
	Sumit Semwal <sumit.semwal@...aro.org>, christian.koenig@....com, 
	linux-kernel@...r.kernel.org
Subject: Re: [PATCH v1 1/6] drm/lima: fix devfreq refcount imbalance for job timeouts

On Thu, Jan 18, 2024 at 2:36 AM Qiang Yu <yuq825@...il.com> wrote:
>
> So this is caused by same job trigger both done and timeout handling?
> I think a better way to solve this is to make sure only one handler
> (done or timeout) process the job instead of just making lima_pm_idle()
> unique.

It's not very clear to me how to best ensure that, with the drm_sched
software timeout and the irq happening potentially at the same time.
I think patch 4 in this series describes and covers the most common
case that this would be hit. So maybe now this patch could be dropped
in favour of just that one.
But since this was a bit hard to reproduce and I'm not sure the issue
is entirely covered by that, I just decided to keep this small change
as it prevented all the stack trace reproducers I was able to come up
with.

Erico