[PATCH RFC v3 0/3] Add splash DRM client

[Francesco Valla <francesco@valla.it>]

Hello,

this is the third (and hopefully last) RFC version for the DRM-based
splash screen.

Motivation behind the work can be found in v1 [0]; in a nutshell, the
splash DRM client can draw a splashscreen using:

  - the BMP image supplied by the EFI BGRT;
  - a BMP image loaded as firmware (either built-in or loaded from the
    filesystem);
  - a colored background.

This revision greatly simplifies the image seletion logic; now the EFI
BGRT is always used as first source if enabled, with a fallback to BMP
image loaded as firmware and then to a plain color.

Sanity checks on the EFI BGRT image have been borrowed from the efifb
driver. More complete splash providers (e.g.: Plymouth) have an
extensive management of platform-specific quirks, but I don't think it
would be reasonable to introduce such complexity here.

Additional notes:
  - Rotation is still not managed (and probably won't?).
  - Support for tiled screens is untested.
  - Plain color and BMP sources were tested on QEMU, Beagleplay and
    i.MX93 FRDM.
  - EFI BGRT support was tested using QEMU+OVMF.

Thank you in advance for any feedback.

Best regards,
Francesco

[0] https://lore.kernel.org/all/20251027-drm_client_splash-v1-0-00698933b34a@valla.it

Signed-off-by: Francesco Valla <francesco@valla.it>
---
Changes in v3:
  - Simplified the image selection and management logic, with direct
    fallback from EFI BGRT to MP as firmware
  - Used new drm_draw_can_convert_from_xrgb8888() API
  - Added proper get_unaligned_ calls for EFI BGRT access
  - Fixed Kconfig dependencies
  - Link to v2: https://lore.kernel.org/r/20260106-drm_client_splash-v2-0-6e86a7434b59@valla.it

Changes in v2:
  - Moved from raw dump to BMP format for static image source
  - Removed support for configurable message
  - Removed support for progress bar
  - Added EFI BGRT as image source
Link to v1: https://lore.kernel.org/r/20251027-drm_client_splash-v1-0-00698933b34a@valla.it

To: Maarten Lankhorst <maarten.lankhorst@linux.intel.com>
To: Maxime Ripard <mripard@kernel.org>
To: Thomas Zimmermann <tzimmermann@suse.de>
To: David Airlie <airlied@gmail.com>
To: Simona Vetter <simona@ffwll.ch>
To: Francesco Valla <francesco@valla.it>
To: Jonathan Corbet <corbet@lwn.net>
To: Shuah Khan <skhan@linuxfoundation.org>
Cc: linux-kernel@vger.kernel.org
Cc: dri-devel@lists.freedesktop.org
Cc: linux-doc@vger.kernel.org

---
Francesco Valla (3):
      drm: client: add splash client
      MAINTAINERS: add entry for DRM splash client
      drm: docs: remove bootsplash from TODO

 Documentation/gpu/todo.rst                    |  17 -
 MAINTAINERS                                   |   7 +
 drivers/gpu/drm/clients/Kconfig               |  63 +-
 drivers/gpu/drm/clients/Makefile              |   1 +
 drivers/gpu/drm/clients/drm_client_internal.h |   9 +
 drivers/gpu/drm/clients/drm_client_setup.c    |   8 +
 drivers/gpu/drm/clients/drm_splash.c          | 932 ++++++++++++++++++++++++++
 7 files changed, 1019 insertions(+), 18 deletions(-)
---
base-commit: afaa0a477099cb7256e26fe11289c753a225ac97
change-id: 20251026-drm_client_splash-e10d7d663e7f

Best regards,
--  
Francesco Valla <francesco@valla.it>