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Date:   Tue, 4 Jul 2023 10:20:34 +0300
From:   Andy Shevchenko <andriy.shevchenko@linux.intel.com>
To:     Javier Martinez Canillas <javierm@redhat.com>
Cc:     linux-kernel@vger.kernel.org,
        Geert Uytterhoeven <geert@linux-m68k.org>,
        Thomas Zimmermann <tzimmermann@suse.de>,
        Arnd Bergmann <arnd@arndb.de>, Borislav Petkov <bp@alien8.de>,
        Daniel Vetter <daniel@ffwll.ch>,
        Dave Hansen <dave.hansen@linux.intel.com>,
        Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
        "H. Peter Anvin" <hpa@zytor.com>, Helge Deller <deller@gmx.de>,
        Ingo Molnar <mingo@redhat.com>,
        Randy Dunlap <rdunlap@infradead.org>,
        Sam Ravnborg <sam@ravnborg.org>,
        Thomas Gleixner <tglx@linutronix.de>,
        dri-devel@lists.freedesktop.org, linux-fbdev@vger.kernel.org,
        x86@kernel.org
Subject: Re: [PATCH v4 4/5] fbdev: Split frame buffer support in FB and
 FB_CORE symbols
Message-ID: <ZKPIQngz6WkzASqa@smile.fi.intel.com>
References: <20230703230534.997525-1-javierm@redhat.com>
 <20230703230534.997525-5-javierm@redhat.com>
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On Tue, Jul 04, 2023 at 01:05:28AM +0200, Javier Martinez Canillas wrote:
> Currently the CONFIG_FB option has to be enabled even if no legacy fbdev
> drivers are needed (e.g: only to have support for framebuffer consoles).
> 
> The DRM subsystem has a fbdev emulation layer, but depends on CONFIG_FB
> and so it can only be enabled if that dependency is enabled as well.
> 
> That means fbdev drivers have to be explicitly disabled if users want to
> enable CONFIG_FB, only to use fbcon and/or the DRM fbdev emulation layer.
> 
> This patch introduces a non-visible CONFIG_FB_CORE symbol that could be
> enabled just to have core support needed for CONFIG_DRM_FBDEV_EMULATION,
> allowing CONFIG_FB to be disabled (and automatically disabling all the
> fbdev drivers).
> 
> Nothing from fb_backlight.o and fbmon.o is used by the DRM fbdev emulation
> layer so these two objects can be compiled out when CONFIG_FB is disabled.

...

Wondering if

  if FB_CORE
  ...
  endif

makes Kconfig looking better instead of replacing all these "depends on" lines.

>  config FB_DEVICE
>  	bool "Provide legacy /dev/fb* device"
> -	depends on FB
> +	depends on FB_CORE
>  	default y

-- 
With Best Regards,
Andy Shevchenko