linux-kernel - Re: [PATCH] drm: fix up fbdev Kconfig defaults

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Message-ID: <87fs3k2dg5.fsf@minerva.mail-host-address-is-not-set>
Date:   Tue, 12 Sep 2023 07:00:26 +0200
From:   Javier Martinez Canillas <javierm@...hat.com>
To:     Arnd Bergmann <arnd@...nel.org>,
        Maarten Lankhorst <maarten.lankhorst@...ux.intel.com>,
        Maxime Ripard <mripard@...nel.org>,
        Thomas Zimmermann <tzimmermann@...e.de>,
        David Airlie <airlied@...il.com>,
        Daniel Vetter <daniel@...ll.ch>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        Helge Deller <deller@....de>
Cc:     Arnd Bergmann <arnd@...db.de>,
        Geert Uytterhoeven <geert@...ux-m68k.org>,
        Christian König <christian.koenig@....com>,
        Dave Airlie <airlied@...hat.com>,
        Jim Cromie <jim.cromie@...il.com>,
        Sam Ravnborg <sam@...nborg.org>,
        Arthur Grillo <arthurgrillo@...eup.net>,
        dri-devel@...ts.freedesktop.org, linux-kernel@...r.kernel.org,
        linux-fbdev@...r.kernel.org
Subject: Re: [PATCH] drm: fix up fbdev Kconfig defaults

Arnd Bergmann <arnd@...nel.org> writes:

Hello Arnd,

> From: Arnd Bergmann <arnd@...db.de>
>
> As a result of the recent Kconfig reworks, the default settings for the
> framebuffer interfaces changed in unexpected ways:
>
> Configurations that leave CONFIG_FB disabled but use DRM now get
> DRM_FBDEV_EMULATION by default. This also turns on the deprecated /dev/fb
> device nodes for machines that don't actually want it.
>
> In turn, configurations that previously had DRM_FBDEV_EMULATION enabled
> now only get the /dev/fb front-end but not the more useful framebuffer
> console, which is not selected any more.
>
> We had previously decided that any combination of the three frontends
> (FB_DEVICE, FRAMEBUFFER_CONSOLE and LOGO) should be selectable, but the
> new default settings mean that a lot of defconfig files would have to
> get adapted.
>
> Change the defaults back to what they were in Linux 6.5:
>
>  - Leave DRM_FBDEV_EMULATION turned off unless CONFIG_FB
>    is enabled. Previously this was a hard dependency but now the two are
>    independent. However, configurations that enable CONFIG_FB probably
>    also want to keep the emulation for DRM, while those without FB
>    presumably did that intentionally in the past.
>
>  - Leave FB_DEVICE turned off for FB=n. Following the same
>    logic, the deprecated option should not automatically get enabled
>    here, most users that had FB turned off in the past do not want it,
>    even if they want the console
>
>  - Turn the FRAMEBUFFER_CONSOLE option on if
>    DRM_FBDEV_EMULATION is set to avoid having to change defconfig
>    files that relied on it being selected unconditionally in the past.
>    This also makes sense since both LOGO and FB_DEVICE are now disabled
>    by default for builds without CONFIG_FB, but DRM_FBDEV_EMULATION
>    would make no sense if all three are disabled.
>
> Fixes: a5ae331edb02b ("drm: Drop select FRAMEBUFFER_CONSOLE for DRM_FBDEV_EMULATION")
> Fixes: 701d2054fa317 ("fbdev: Make support for userspace interfaces configurable")
> Reported-by: Geert Uytterhoeven <geert@...ux-m68k.org>
> Signed-off-by: Arnd Bergmann <arnd@...db.de>
> ---

Thanks for fixing this and sorry that I missed the defaults changed.

Reviewed-by: Javier Martinez Canillas <javierm@...hat.com>

-- 
Best regards,

Javier Martinez Canillas
Core Platforms
Red Hat