linux-kernel - Re: [PATCH 0/2] Allow disabling all native fbdev drivers and only keeping DRM emulation

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Date:   Mon, 03 Jul 2023 10:43:46 +0200
From:   Javier Martinez Canillas <javierm@...hat.com>
To:     Andy Shevchenko <andriy.shevchenko@...ux.intel.com>
Cc:     linux-kernel@...r.kernel.org,
        Geert Uytterhoeven <geert@...ux-m68k.org>,
        Thomas Zimmermann <tzimmermann@...e.de>,
        Arnd Bergmann <arnd@...db.de>, Borislav Petkov <bp@...en8.de>,
        Daniel Vetter <daniel@...ll.ch>,
        Dave Hansen <dave.hansen@...ux.intel.com>,
        David Airlie <airlied@...il.com>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        "H. Peter Anvin" <hpa@...or.com>, Helge Deller <deller@....de>,
        Ingo Molnar <mingo@...hat.com>,
        Maarten Lankhorst <maarten.lankhorst@...ux.intel.com>,
        Maxime Ripard <mripard@...nel.org>,
        Randy Dunlap <rdunlap@...radead.org>,
        Sam Ravnborg <sam@...nborg.org>,
        Thomas Gleixner <tglx@...utronix.de>,
        dri-devel@...ts.freedesktop.org, linux-fbdev@...r.kernel.org,
        x86@...nel.org
Subject: Re: [PATCH 0/2] Allow disabling all native fbdev drivers and only
 keeping DRM emulation

Andy Shevchenko <andriy.shevchenko@...ux.intel.com> writes:

> On Fri, Jun 30, 2023 at 10:29:20PM +0200, Javier Martinez Canillas wrote:
>> Andy Shevchenko <andriy.shevchenko@...ux.intel.com> writes:
>> > On Fri, Jun 30, 2023 at 07:38:01PM +0200, Javier Martinez Canillas wrote:
>> >> Andy Shevchenko <andriy.shevchenko@...ux.intel.com> writes:
>> >> > On Fri, Jun 30, 2023 at 12:51:02AM +0200, Javier Martinez Canillas wrote:
>> >> >> This patch series splits the fbdev core support in two different Kconfig
>> >> >> symbols: FB and FB_CORE. The motivation for this is to allow CONFIG_FB to
>> >> >> be disabled, while still having the the core fbdev support needed for the
>> >> >> CONFIG_DRM_FBDEV_EMULATION to be enabled. The motivation is automatically
>> >> >> disabling all fbdev drivers instead of having to be disabled individually.
>> >> >> 
>> >> >> The reason for doing this is that now with simpledrm, there's no need for
>> >> >> the legacy fbdev (e.g: efifb or vesafb) drivers anymore and many distros
>> >> >
>> >> > How does simpledrm works with earlycon=efi?
>> >> >
>> >> 
>> >> simpledrm isn't for earlycon. For that you use a different driver (i.e:
>> >> drivers/firmware/efi/earlycon.c). I'm just talking about fbdev drivers
>> >> here that could be replaced by simpledrm.
>> >
>> > So, efifb can't be replaced. Please, fix your cover letter to reduce false
>> > impression of the scope of usage of the simpledrm.
>> >
>> 
>> Nothing to fixup.
>> 
>> You are conflating the efifb fbdev driver (drivers/video/fbdev/efifb.c)
>> with the efifb earlycon driver (drivers/firmware/efi/earlycon.c). I'm
>> talking about the former (which can be replaced by simpledrm) while you
>> are talking about the latter.
>
> Ah, this makes sense!
>
> I remember now that it was (still is?) an attempt to move from efifb to
> simpledrm, but have no idea what the status of that series is.
>

Indeed. And there was were also some patches IIRC to attempt porting the
earlycon efifb to a fbdev or DRM driver, can't remember now.

> -- 
> With Best Regards,
> Andy Shevchenko
>
>

-- 
Best regards,

Javier Martinez Canillas
Core Platforms
Red Hat