linux-kernel - Re: [PATCH v3] firmware/sysfb: Fix VESA format selection

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Message-ID: <d8d22c77-1bde-774f-aa6e-41234ffa6e8d@suse.de>
Date:   Fri, 21 Apr 2023 13:35:35 +0200
From:   Thomas Zimmermann <tzimmermann@...e.de>
To:     Linux regressions mailing list <regressions@...ts.linux.dev>,
        Pierre Asselin <pa@...ix.com>, dri-devel@...ts.freedesktop.org
Cc:     Daniel Vetter <daniel.vetter@...ll.ch>,
        Javier Martinez Canillas <javierm@...hat.com>,
        linux-kernel@...r.kernel.org, Hans de Goede <hdegoede@...hat.com>,
        Ard Biesheuvel <ardb@...nel.org>
Subject: Re: [PATCH v3] firmware/sysfb: Fix VESA format selection

Hi

Am 21.04.23 um 13:32 schrieb Linux regression tracking (Thorsten Leemhuis):
> On 20.04.23 17:57, Pierre Asselin wrote:
>> Some legacy BIOSes report no reserved bits in their 32-bit rgb mode,
>> breaking the calculation of bits_per_pixel in commit f35cd3fa7729
>> ("firmware/sysfb: Fix EFI/VESA format selection").  However they report
>> lfb_depth correctly for those modes.  Keep the computation but
>> set bits_per_pixel to lfb_depth if the latter is larger.
>>
>> v2 fixes the warnings from a max3() macro with arguments of different
>> types;  split the bits_per_pixel assignment to avoid uglyfing the code
>> with too many casts.
>>
>> v3 fixes space and formatting blips pointed out by Javier, and change
>> the bit_per_pixel assignment back to a single statement using two casts.
>>
>> Link: https://lore.kernel.org/r/4Psm6B6Lqkz1QXM@panix3.panix.com
>> Link: https://lore.kernel.org/r/20230412150225.3757223-1-javierm@redhat.com
>> Link: https://lore.kernel.org/dri-devel/20230418183325.2327-1-pa@panix.com/T/#u
>> Link: https://lore.kernel.org/dri-devel/20230419044834.10816-1-pa@panix.com/T/#u
>> Fixes: f35cd3fa7729 ("firmware/sysfb: Fix EFI/VESA format selection")
>> Signed-off-by: Pierre Asselin <pa@...ix.com>
> 
> Linus might release the final this weekend and this is among the last
> few 6.3 regressions I track. Hence please allow me to ask:
> 
> Pierre, Tomas, Javier, et. al: how many "legacy BIOSes" do we suspect
> are affected by this? So many that it might be worth delaying the
> release by one week? And in case everybody involved might agree that
> this patch is ready by today or tomorrow: might it be worth asking Linus
> to merge this patch directly[1]?
> 
> [FWIW, I highly suspect the answer to the last two questions is "no,
> that's definitely not worth is", just wanted to confirm]

IMHO it's a fairly obscure bug and certainly not a release blocker. I'll 
send it through the regular channels of the DRM subsystem.

Best regards
Thomas

> 
> Ciao, Thorsten (wearing his 'the Linux kernel's regression tracker' hat)
> --
> Everything you wanna know about Linux kernel regression tracking:
> https://linux-regtracking.leemhuis.info/about/#tldr
> If I did something stupid, please tell me, as explained on that page.
> 
> [1] yes, that's a thing we do:
> https://lore.kernel.org/all/CAHk-=wis_qQy4oDNynNKi5b7Qhosmxtoj1jxo5wmB6SRUwQUBQ@mail.gmail.com/

-- 
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)

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