linux-kernel - Re: [PATCH] drm: Drop select FRAMEBUFFER_CONSOLE for DRM_FBDEV

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Date:   Fri, 4 Aug 2023 15:07:17 +0200
From:   Daniel Vetter <daniel@...ll.ch>
To:     Javier Martinez Canillas <javierm@...hat.com>
Cc:     linux-kernel@...r.kernel.org, Arnd Bergmann <arnd@...db.de>,
        Arthur Grillo <arthurgrillo@...eup.net>,
        Randy Dunlap <rdunlap@...radead.org>,
        David Airlie <airlied@...il.com>, Helge Deller <deller@....de>,
        Maarten Lankhorst <maarten.lankhorst@...ux.intel.com>,
        Maxime Ripard <mripard@...nel.org>,
        Thomas Zimmermann <tzimmermann@...e.de>,
        dri-devel@...ts.freedesktop.org
Subject: Re: [PATCH] drm: Drop select FRAMEBUFFER_CONSOLE for DRM_FBDEV_EMULATION

On Fri, 4 Aug 2023 at 14:52, Javier Martinez Canillas
<javierm@...hat.com> 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@...eup.net>
> Closes: https://lore.kernel.org/dri-devel/20230726220325.278976-1-arthurgrillo@riseup.net
> Suggested-by: Arnd Bergmann <arnd@...db.de>
> Signed-off-by: Javier Martinez Canillas <javierm@...hat.com>

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 :-)

Acked-by: Daniel Vetter <daniel.vetter@...ll.ch>

Cheers, Sima

> ---
>
>  drivers/gpu/drm/Kconfig | 1 -
>  1 file changed, 1 deletion(-)
>
> diff --git a/drivers/gpu/drm/Kconfig b/drivers/gpu/drm/Kconfig
> index b51c6a141dfa..2a44b9419d4d 100644
> --- a/drivers/gpu/drm/Kconfig
> +++ b/drivers/gpu/drm/Kconfig
> @@ -135,7 +135,6 @@ config DRM_DEBUG_MODESET_LOCK
>  config DRM_FBDEV_EMULATION
>         bool "Enable legacy fbdev support for your modesetting driver"
>         depends on DRM
> -       select FRAMEBUFFER_CONSOLE if !EXPERT
>         select FRAMEBUFFER_CONSOLE_DETECT_PRIMARY if FRAMEBUFFER_CONSOLE
>         default y
>         help
> --
> 2.41.0
>


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