linux-kernel - [PATCH v2 0/2] Allow disabling all native fbdev drivers and only keeping DRM emulation

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Message-ID: <20230701214503.550549-1-javierm@redhat.com>
Date:   Sat,  1 Jul 2023 23:44:49 +0200
From:   Javier Martinez Canillas <javierm@...hat.com>
To:     linux-kernel@...r.kernel.org
Cc:     Thomas Zimmermann <tzimmermann@...e.de>,
        Geert Uytterhoeven <geert@...ux-m68k.org>,
        Arnd Bergmann <arnd@...db.de>,
        Javier Martinez Canillas <javierm@...hat.com>,
        Andy Shevchenko <andriy.shevchenko@...ux.intel.com>,
        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: [PATCH v2 0/2] Allow disabling all native fbdev drivers and only keeping DRM emulation

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
now disable them. But it would simplify the config a lot fo have a single
Kconfig symbol to disable all fbdev drivers.

I've built tested with possible combinations of CONFIG_FB, CONFIG_FB_CORE,
CONFIG_DRM_FBDEV_EMULATION and CONFIG_FB_DEVICE symbols set to 'y' or 'n'.

Patch 1/2 makes the CONFIG_FB split that is mentioned above and patch 2/2
makes the DRM fbdev emulation to select the new FB_CORE symbol instead of
depending on FB.

This is a v2 of the patch-set that addresses issues pointed out by Arnd
Bergmann and Thomas Zimmermann in the previous version:

https://lists.freedesktop.org/archives/dri-devel/2023-June/411435.html

Changes in v2:
- Keep "depends on FB" for FB_DDC, FB_HECUBA, FB_SVGALIB, FB_MACMODES,
  FB_BACKLIGHT, FB_MODE_HELPERS and FB_TILEBLITTING (Arnd Bergmann).
- Don't change the fb.o object name (Arnd Bergmann).
- Make FB_CORE a non-visible Kconfig symbol instead (Thomas Zimmermann).
- Make CONFIG_DRM_FBDEV_EMULATION to select FB_CORE (Thomas Zimmermann).

Javier Martinez Canillas (2):
  fbdev: Split frame buffer support in FB and FB_CORE symbols
  drm: Make fbdev emulation select FB_CORE instead of depends on FB

 arch/x86/Makefile                 |  2 +-
 arch/x86/video/Makefile           |  2 +-
 drivers/gpu/drm/Kconfig           |  2 +-
 drivers/video/console/Kconfig     |  2 +-
 drivers/video/fbdev/Kconfig       | 40 +++++++++++++++++++------------
 drivers/video/fbdev/core/Makefile |  2 +-
 6 files changed, 30 insertions(+), 20 deletions(-)

base-commit: 270689d257c88fd1ad7050041ed196a8188e6914
-- 
2.41.0