On Mon, Dec 16, 2024, at 08:42, Thomas Zimmermann wrote:

Fix the dependencies among the various graphics modules.

Before addressing the FB_CORE issue, patch 1 first resolves a problem
with BACKLIGHT_CLASS_DEVICE. A number of fbdev drivers select it, which
results in a recursive-dependency error after patch has been applied.
Making these drivers (or parts of them) depend on BACKLIGHT_CLASS_DEVICE
fixes this.

Patch 2 selects FB_CORE for DRM_GEM_DMA_HELPER and DRM_TTM_HELPER.
This is necessary with the recently added DRM client library.

Patch 3 is the second half of the patch provided by Arnd at [1]. It
could not yet be merged because of the issues fixed by patch 1.

Side note: For the majority of graphics drivers, backlight functionality
depends on BACKLIGHT_CLASS_DEVICE. In a few cases drivers select the
Kconfig token automatically. These drivers should be updated to depend
on the token as well, such that backlight functionality is fully user-
controlled.

v3:
- Fix PMAC_BACKLIGHT case (Christophe)
v2:

The patches look good to me. I've had a slightly different version
in my randconfig test tree and have replaced it with yours now
to do some more regression testing, but I expect this to be fine.

Reviewed-by: Arnd Bergmann <arnd@arndb.de>