On Tue, Dec 10, 2024, at 15:09, Thomas Zimmermann wrote: > Do not select BACKLIGHT_CLASS_DEVICE from FB_BACKLIGHT. The latter > only controls backlight support within fbdev core code and data > structures. > > Make fbdev drivers depend on BACKLIGHT_CLASS_DEVICE and let users > select it explicitly. Fixes warnings about recursive dependencies, > such as > > error: recursive dependency detected! > symbol BACKLIGHT_CLASS_DEVICE is selected by FB_BACKLIGHT > symbol FB_BACKLIGHT is selected by FB_SH_MOBILE_LCDC > symbol FB_SH_MOBILE_LCDC depends on FB_DEVICE > symbol FB_DEVICE depends on FB_CORE > symbol FB_CORE is selected by DRM_GEM_DMA_HELPER > symbol DRM_GEM_DMA_HELPER is selected by DRM_PANEL_ILITEK_ILI9341 > symbol DRM_PANEL_ILITEK_ILI9341 depends on BACKLIGHT_CLASS_DEVICE > > BACKLIGHT_CLASS_DEVICE is user-selectable, so making drivers adapt to > it is the correct approach in any case. For most drivers, backlight > support is also configurable separately. > > Signed-off-by: Thomas Zimmermann <tzimmermann@xxxxxxx> Thanks for revisiting this! My patch that failed to work correctly happened to work on my randconfig tree because I still have an old variant of this change, see https://lore.kernel.org/linux-fbdev/20200417155553.675905-8-arnd@xxxxxxxx/ This is almost the same as your version, except for the optional fbdev Kconfig bits PERS > @@ -660,7 +661,6 @@ config FB_ATMEL > config FB_NVIDIA > tristate "nVidia Framebuffer Support" > depends on FB && PCI > - select FB_BACKLIGHT if FB_NVIDIA_BACKLIGHT > select FB_CFB_FILLRECT > select FB_CFB_COPYAREA > select FB_CFB_IMAGEBLIT > @@ -700,6 +700,8 @@ config FB_NVIDIA_DEBUG > config FB_NVIDIA_BACKLIGHT > bool "Support for backlight control" > depends on FB_NVIDIA > + depends on BACKLIGHT_CLASS_DEVICE > + select FB_BACKLIGHT > default y > help > Say Y here if you want to control the backlight of your display. For instance here I used @@ -702,6 +703,7 @@ config FB_NVIDIA_DEBUG config FB_NVIDIA_BACKLIGHT bool "Support for backlight control" depends on FB_NVIDIA + depends on BACKLIGHT_CLASS_DEVICE=y || BACKLIGHT_CLASS_DEVICE=FB_NVIDIA default y help Say Y here if you want to control the backlight of your display. while your patch causes a link failure with CONFIG_FB_NVIDIA=y CONFIG_FB_NVIDIA_BACKLIGHT=y CONFIG_BACKLIGHT_CLASS_DEVICE=m Arnd
