[PATCH v3 11/13] drm/fb-helper: Fix single-probe color-format selection

[Linux regression tracking #adding (Thorsten Leemhuis)]

[CCing the regression list, as it should be in the loop for regressions:
https://docs.kernel.org/admin-guide/reporting-regressions.html]

[TLDR: I'm adding this report to the list of tracked Linux kernel
regressions; the text you find below is based on a few templates
paragraphs you might have encountered already in similar form.
See link in footer if these mails annoy you.]

On 12.05.23 15:20, Linus Walleij wrote:
> Sorry for late regression detection but this patch regresses
> the Integrator AB IMPD-1 graphics, I bisected down to this
> patch.
> 
> On Mon, Jan 2, 2023 at 12:30 PM Thomas Zimmermann <tzimmermann at suse.de> wrote:
> [...]
> Before this patch:
> 
> [drm] Initialized pl111 1.0.0 20170317 for c1000000.display on minor 0
> drm-clcd-pl111 c1000000.display: [drm] requested bpp 16, scaled depth down to 15
> drm-clcd-pl111 c1000000.display: enable IM-PD1 CLCD connectors
> Console: switching to colour frame buffer device 80x30
> drm-clcd-pl111 c1000000.display: [drm] fb0: pl111drmfb frame buffer device
> 
> After this patch:
> 
> [drm] Initialized pl111 1.0.0 20170317 for c1000000.display on minor 0
> drm-clcd-pl111 c1000000.display: [drm] bpp/depth value of 16/16 not supported
> drm-clcd-pl111 c1000000.display: [drm] No compatible format found
> drm-clcd-pl111 c1000000.display: [drm] *ERROR* fbdev: Failed to setup
> generic emulation (ret=-12)
> 
> It seems the bpp downscaling stopped to work? [...]

Thanks for the report. To be sure the issue doesn't fall through the
cracks unnoticed, I'm adding it to regzbot, the Linux kernel regression
tracking bot:

#regzbot ^introduced 37c90d589dc
#regzbot title drm/fb-helper: downscaling apparently stopped to work
with pl110_impd1
#regzbot ignore-activity

This isn't a regression? This issue or a fix for it are already
discussed somewhere else? It was fixed already? You want to clarify when
the regression started to happen? Or point out I got the title or
something else totally wrong? Then just reply and tell me -- ideally
while also telling regzbot about it, as explained by the page listed in
the footer of this mail.

Developers: When fixing the issue, remember to add 'Link:' tags pointing
to the report (the parent of this mail). See page linked in footer for
details.

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
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