linux-kernel - Re: drm/fbdev-dma: regression

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Message-ID: <832483d5-db64-4195-a86c-028eff033fbe@suse.de>
Date: Tue, 12 Nov 2024 09:11:31 +0100
From: Thomas Zimmermann <tzimmermann@...e.de>
To: Nuno Gonçalves <nunojpg@...il.com>
Cc: Thorsten Leemhuis <regressions@...mhuis.info>,
 Linux kernel regressions list <regressions@...ts.linux.dev>,
 dri-devel@...ts.freedesktop.org, LKML <linux-kernel@...r.kernel.org>,
 Linux Framebuffer <linux-fbdev@...r.kernel.org>
Subject: Re: drm/fbdev-dma: regression

Hi


Am 11.11.24 um 20:06 schrieb Nuno Gonçalves:
>
>
> On Mon, Nov 11, 2024, 14:37 Thomas Zimmermann <tzimmermann@...e.de> wrote:
>
>     Hi
>
>
>     Am 11.11.24 um 14:42 schrieb Nuno Gonçalves:
>     > On Mon, Nov 11, 2024 at 1:22 PM Thomas Zimmermann
>     <tzimmermann@...e.de> wrote:
>     >> The patch in question changes the whole memory management of the
>     >> affected code. It's also noteworthy that most of it has been
>     reworked
>     >> for the upcoming v6.12. Maybe this already fixed the problem.
>     Kernel
>     >> v6.11-rc7 added commit 5a498d4d06d6 ("drm/fbdev-dma: Only install
>     >> deferred I/O if necessary"), which possibly fixes the problem
>     as well.
>     >>
>     >> But there's no explicit fix for this problem and I have not
>     seen any
>     >> other related reports. Any further information is welcome.
>     > Issue was present since 5ab91447aa13b8b98bc11f5326f33500b0ee2c48 and
>     > tested until 6.12-rc3.
>     > Is there any suggestion on how to dig down?
>
>     Do you have a stack trace of this problem?
>
>
> No. I need to build kernel with debug?

Isn't there an error message in the output of dmesg?

Or maybe can you save the whole output of dmesg after a crash and attach 
the file to an email?

In the original bug report, you mentioned that you often get an error. 
But not 'always'?

Do you have a reproducer for the problem? Such as a very simple program 
that triggers the bug.

>
>
>
>     Which hardware platform is affected?
>
>
> ARM64 with ili9225 and display size 220, 176. It also
> happens in another board with a different tinydrm driver and size 320,
> 240.

I meant, which board or CPU. ARM64/Aarch64 is really just a very broad 
term describing the system.

Best regards
Thomas


-- 
--
Thomas Zimmermann
Graphics Driver Developer
SUSE Software Solutions Germany GmbH
Frankenstrasse 146, 90461 Nuernberg, Germany
GF: Ivo Totev, Andrew Myers, Andrew McDonald, Boudien Moerman
HRB 36809 (AG Nuernberg)