linux-kernel - Re: [PATCH 1/2] drm: introduce page_flip

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Message-ID: <2285353.hkbZ0PkbqX@timur-hyperion>
Date: Thu, 29 Jan 2026 13:06:30 +0100
From: Timur Kristóf <timur.kristof@...il.com>
To: Alex Deucher <alexdeucher@...il.com>,
 Hamza Mahfooz <someguy@...ective-light.com>,
 Michel Dänzer <michel.daenzer@...lbox.org>,
 Christian König <christian.koenig@....com>
Cc: Mario Limonciello <mario.limonciello@....com>,
 dri-devel@...ts.freedesktop.org, Alex Deucher <alexander.deucher@....com>,
 David Airlie <airlied@...il.com>, Simona Vetter <simona@...ll.ch>,
 Harry Wentland <harry.wentland@....com>, Leo Li <sunpeng.li@....com>,
 Rodrigo Siqueira <siqueira@...lia.com>,
 Maarten Lankhorst <maarten.lankhorst@...ux.intel.com>,
 Maxime Ripard <mripard@...nel.org>, Thomas Zimmermann <tzimmermann@...e.de>,
 Sunil Khatri <sunil.khatri@....com>, Ce Sun <cesun102@....com>,
 Lijo Lazar <lijo.lazar@....com>, Kenneth Feng <kenneth.feng@....com>,
 Ivan Lipski <ivan.lipski@....com>, Alex Hung <alex.hung@....com>,
 Tom Chung <chiahsuan.chung@....com>, Melissa Wen <mwen@...lia.com>,
 Fangzhi Zuo <Jerry.Zuo@....com>, amd-gfx@...ts.freedesktop.org,
 linux-kernel@...r.kernel.org
Subject: Re: [PATCH 1/2] drm: introduce page_flip_timeout()

On Thursday, January 29, 2026 12:38:30 PM Central European Standard Time 
Christian König wrote:
> > 
> > However, just like we do with ring timeouts, we also need to be prepared
> > for the situation where a page flip timeout happens and we should try to
> > recover from it. And if it isn't recoverable, fall back to GPU reset.
> 
> No, that is clearly a bad idea.

I don't see why it's "clearly" a bad idea. It's not clear to me at all, please 
clarify it for me.

> CRTCs are fixed function devices that GPU
> reset helps here is just pure coincident.

Currently, the driver doesn't handle page flip timeouts at all, which means 
that if it happens, there is 0% chance of recovering from it.

If the GPU reset improves that chance to non-zero, it's already an 
improvement, and already more than what AMD did to address this problem for 
the past few years. I just find it incredibly disrespectful towards the 
community that AMD proposes a solution that they neglect to implement, then 
when somebody from the community steps up to implement it, it's rejected.

> What we can certainly do is to improve the error handling, e.g. that the
> system doesn't sit there forever after a page flip timeout.

Sure.

> 
> Let's maybe try a complete different approach. We force a page flip timeout,
> and see if the system can handle that or not.
> 
> E.g. every 300 page flip we just fail to signal and see if things still work
> after the timeout.

How do you propose to do that?