linux-kernel - Re: [PATCH 1/3] backlight: always select BACKLIGHT_LCD_SUPPORT for BACKLIGHT_CLASS

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Date:   Wed, 26 Jul 2017 18:38:10 +0300
From:   Andy Shevchenko <andy.shevchenko@...il.com>
To:     Arnd Bergmann <arnd@...db.de>
Cc:     dri-devel@...ts.freedesktop.org,
        "Rafael J. Wysocki" <rjw@...ysocki.net>,
        Len Brown <lenb@...nel.org>,
        Lucas Stach <l.stach@...gutronix.de>,
        Russell King <linux+etnaviv@...linux.org.uk>,
        Christian Gmeiner <christian.gmeiner@...il.com>,
        David Airlie <airlied@...ux.ie>,
        Patrik Jakobsson <patrik.r.jakobsson@...il.com>,
        Daniel Vetter <daniel.vetter@...el.com>,
        Jani Nikula <jani.nikula@...ux.intel.com>,
        Ben Skeggs <bskeggs@...hat.com>,
        Darren Hart <dvhart@...radead.org>,
        Andy Shevchenko <andy@...radead.org>,
        Jens Frederich <jfrederich@...il.com>,
        Daniel Drake <dsd@...top.org>,
        Jon Nettleton <jon.nettleton@...il.com>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        "linux-acpi@...r.kernel.org" <linux-acpi@...r.kernel.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        etnaviv@...ts.freedesktop.org, intel-gfx@...ts.freedesktop.org,
        nouveau@...ts.freedesktop.org,
        Platform Driver <platform-driver-x86@...r.kernel.org>,
        devel@...verdev.osuosl.org
Subject: Re: [PATCH 1/3] backlight: always select BACKLIGHT_LCD_SUPPORT for BACKLIGHT_CLASS_DEVICE

On Wed, Jul 26, 2017 at 4:53 PM, Arnd Bergmann <arnd@...db.de> 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@...il.com>

-- 
With Best Regards,
Andy Shevchenko