linux-kernel - Re: [PATCH] fbdev: Prevent probing generic drivers if a FB is already registered

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Date:   Thu, 11 Nov 2021 11:00:22 +0100
From:   Daniel Vetter <daniel@...ll.ch>
To:     Thorsten Leemhuis <regressions@...mhuis.info>
Cc:     Javier Martinez Canillas <javierm@...hat.com>,
        linux-kernel@...r.kernel.org, linux-fbdev@...r.kernel.org,
        Daniel Vetter <daniel.vetter@...ll.ch>,
        dri-devel@...ts.freedesktop.org,
        Thomas Zimmermann <tzimmermann@...e.de>,
        Ilya Trukhanov <lahvuun@...il.com>,
        Sam Ravnborg <sam@...nborg.org>
Subject: Re: [PATCH] fbdev: Prevent probing generic drivers if a FB is
 already registered

On Thu, Nov 11, 2021 at 10:58:14AM +0100, Thorsten Leemhuis wrote:
> On 11.11.21 10:20, Javier Martinez Canillas wrote:
> > The efifb and simplefb drivers just render to a pre-allocated frame buffer
> > and rely on the display hardware being initialized before the kernel boots.
> > 
> > But if another driver already probed correctly and registered a fbdev, the
> > generic drivers shouldn't be probed since an actual driver for the display
> > hardware is already present.
> > 
> > Reported-by: Ilya Trukhanov <lahvuun@...il.com>
> > Signed-off-by: Javier Martinez Canillas <javierm@...hat.com>
> > ---
> 
> TLDR: Javier, in case you need to send an improved patch, could you
> please add this before the 'Reported-by:'
> 
> Link: https://lore.kernel.org/r/20211110200253.rfudkt3edbd3nsyj@lahvuun/

Uh I thought Link: was for the patch submission chain, and we've used
References: for bug reports and everything else. Is the extension of Link:
a new thing?
-Daniel

> 
> And if the patch is already good to go: could the subsystem maintainer
> please add it when applying?
> 
> 
> Long story: hi, this is your Linux kernel regression tracker speaking.
> Thanks for working on a fix for a regression I'm keeping an eye on.
> 
> There is one small detail that could be improved: the commit message
> would benefit from a link to the regression report, for reasons
> explained in Documentation/process/submitting-patches.rst. To quote:
> 
> ```
> If related discussions or any other background information behind the
> change can be found on the web, add 'Link:' tags pointing to it. In case
> your patch fixes a bug, for example, add a tag with a URL referencing
> the report in the mailing list archives or a bug tracker;
> ```
> 
> This concept is old, but the text was reworked recently to make this use
> case for the Link: tag clearer. For details see:
> https://git.kernel.org/linus/1f57bd42b77c
> 
> Yes, that "Link:" is not really crucial; but it's good to have if
> someone needs to look into the backstory of this change sometime in the
> future. But I care for a different reason. I'm tracking this regression
> (and others) with regzbot, my Linux kernel regression tracking bot. This
> bot will notice if a patch with a Link: tag to a tracked regression gets
> posted and record that, which allowed anyone looking into the regression
> to quickly gasp the current status from regzbot's webui
> (https://linux-regtracking.leemhuis.info/regzbot ) or its reports. The
> bot will also notice if a commit with a Link: tag to a regression report
> is applied by Linus and then automatically mark the regression as
> resolved then.
> 
> IOW: this tag makes my life a regression tracker a lot easier, as I
> otherwise have to tell regzbot manually about the fix. ;-)
> 
> Ciao, Thorsten (while carrying his Linux kernel regression tracker hat)
> 
> #regzbot ^backmonitor
> https://lore.kernel.org/r/20211110200253.rfudkt3edbd3nsyj@lahvuun/

-- 
Daniel Vetter
Software Engineer, Intel Corporation
http://blog.ffwll.ch