Re: [PATCH] drm: Drop select FRAMEBUFFER_CONSOLE for DRM_FBDEV_EMULATION

[Javier Martinez Canillas]

"Arnd Bergmann" <arnd@xxxxxxxx> writes:

> On Fri, Aug 4, 2023, at 15:07, Daniel Vetter wrote:
>> On Fri, 4 Aug 2023 at 14:52, Javier Martinez Canillas
>> <javierm@xxxxxxxxxx> wrote:
>>>
>>> The commit c242f48433e7 ("drm: Make FB_CORE to be selected if DRM fbdev
>>> emulation is enabled") changed DRM_FBDEV_EMULATION from 'depends on FB'
>>> to an effective 'select FB_CORE', so any config that previously had DRM=y
>>> and FB=n now has FB_CORE=y and FRAMEBUFFER_CONSOLE=y.
>>>
>>> This leads to unmet direct dependencies detected for FRAMEBUFFER_CONSOLE
>>> as reported by Arthur Grillo, e.g:
>>>
>>> WARNING: unmet direct dependencies detected for FRAMEBUFFER_CONSOLE
>>>   Depends on [n]: VT [=n] && FB_CORE [=y] && !UML [=y]
>>>   Selected by [y]:
>>>   - DRM_FBDEV_EMULATION [=y] && HAS_IOMEM [=y] && DRM [=y] && !EXPERT [=n]
>>>
>>> Arnd Bergmann suggests to drop the select FRAMEBUFFER_CONSOLE for the
>>> DRM_FBDEV_EMULATION Kconfig symbol, since a possible use case could
>>> be to enable DRM fbdev emulation but without a framebuffer console.
>>>
>>> Fixes: c242f48433e7 ("drm: Make FB_CORE to be selected if DRM fbdev emulation is enabled")
>>> Reported-by: Arthur Grillo <arthurgrillo@xxxxxxxxxx>
>>> Closes: https://lore.kernel.org/dri-devel/20230726220325.278976-1-arthurgrillo@xxxxxxxxxx
>>> Suggested-by: Arnd Bergmann <arnd@xxxxxxxx>
>>> Signed-off-by: Javier Martinez Canillas <javierm@xxxxxxxxxx>
>>
>> Yeah originally this was just to help people not misconfigure their
>> kernels and end up with a black screen. But select is really not a
>> nice way to do that, imo we could drop the FB_CORE select too :-)
>
> Droping the 'FB_CORE' select only works if we make FB_CORE user
> visible and add a 'depends on' for it instead. Not sure this
> is any better since this would only ever be used when either
> CONFIG_FB or CONFIG_DRM_FBDEV_EMULATION is enabled.
>

Agreed.

-- 
Best regards,

Javier Martinez Canillas
Core Platforms
Red Hat