Re: [PATCH 1/3] backlight: always select BACKLIGHT_LCD_SUPPORT for BACKLIGHT_CLASS_DEVICE

[Andy Shevchenko]

On Wed, Jul 26, 2017 at 4:53 PM, Arnd Bergmann <arnd@xxxxxxxx> wrote:
> randconfig builds occasionally produce this Kconfig warning:
>
> warning: (DRM_RADEON && DRM_AMDGPU && DRM_NOUVEAU && DRM_I915 && DRM_GMA500 && DRM_SHMOBILE && DRM_TILCDC && DRM_FSL_DCU && DRM_TINYDRM && DRM_PARADE_PS8622 && FB_BACKLIGHT && FB_ARMCLCD && FB_MX3 && USB_APPLEDISPLAY && FB_OLPC_DCON && ACPI_CMPC && SAMSUNG_Q10) selects BACKLIGHT_CLASS_DEVICE which has unmet direct dependencies (HAS_IOMEM && BACKLIGHT_LCD_SUPPORT)
>
> It turns out that amost all users of BACKLIGHT_CLASS_DEVICE also select
> BACKLIGHT_LCD_SUPPORT, but not all of them do. This makes the remaining
> ones behave like the others.
>
> It would probably be best to rework the way those two options related
> entirely, but for now this takes the simpler and safer approach to
> fix the warnings without introducing regressions.

> diff --git a/drivers/platform/x86/Kconfig b/drivers/platform/x86/Kconfig
> index 80b87954f6dd..e0ca673bf564 100644
> --- a/drivers/platform/x86/Kconfig
> +++ b/drivers/platform/x86/Kconfig
> @@ -785,6 +785,7 @@ config ACPI_CMPC
>         depends on RFKILL || RFKILL=n
>         select INPUT
>         select BACKLIGHT_CLASS_DEVICE
> +       select BACKLIGHT_LCD_SUPPORT
>         default n
>         help
>           Support for Intel Classmate PC ACPI devices, including some
> @@ -1000,6 +1001,7 @@ config SAMSUNG_Q10
>         tristate "Samsung Q10 Extras"
>         depends on ACPI
>         select BACKLIGHT_CLASS_DEVICE
> +       select BACKLIGHT_LCD_SUPPORT
>         ---help---
>           This driver provides support for backlight control on Samsung Q10
>           and related laptops, including Dell Latitude X200.

Acked-by: Andy Shevchenko <andy.shevchenko@xxxxxxxxx>

-- 
With Best Regards,
Andy Shevchenko