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From:   Javier Martinez Canillas <javierm@redhat.com>
To:     Arnd Bergmann <arnd@arndb.de>, Daniel Vetter <daniel@ffwll.ch>
Cc:     linux-kernel@vger.kernel.org,
        Arthur Grillo <arthurgrillo@riseup.net>,
        Randy Dunlap <rdunlap@infradead.org>,
        Dave Airlie <airlied@gmail.com>, Helge Deller <deller@gmx.de>,
        Maarten Lankhorst <maarten.lankhorst@linux.intel.com>,
        Maxime Ripard <mripard@kernel.org>,
        Thomas Zimmermann <tzimmermann@suse.de>,
        dri-devel@lists.freedesktop.org
Subject: Re: [PATCH] drm: Drop select FRAMEBUFFER_CONSOLE for
 DRM_FBDEV_EMULATION
In-Reply-To: <19a2a2a0-2f35-4c4e-926c-47b75e6f9353@app.fastmail.com>
References: <20230804125156.1387542-1-javierm@redhat.com>
 <CAKMK7uH=7m=2Y0SxPm2Q1J+u2MRWHNQrYy7M5se7Ua9ZA19y=A@mail.gmail.com>
 <19a2a2a0-2f35-4c4e-926c-47b75e6f9353@app.fastmail.com>
Date:   Fri, 04 Aug 2023 16:03:15 +0200
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"Arnd Bergmann" <arnd@arndb.de> writes:

> On Fri, Aug 4, 2023, at 15:07, Daniel Vetter wrote:
>> On Fri, 4 Aug 2023 at 14:52, Javier Martinez Canillas
>> <javierm@redhat.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@riseup.net>
>>> Closes: https://lore.kernel.org/dri-devel/20230726220325.278976-1-arthurgrillo@riseup.net
>>> Suggested-by: Arnd Bergmann <arnd@arndb.de>
>>> Signed-off-by: Javier Martinez Canillas <javierm@redhat.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 :-)
>
> 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