linux-kernel - Re: [PATCH v1] backlight: Don't build support by default

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Message-ID: <7958bf6a-5c2e-1330-1800-f9dbce3c01c6@linaro.org>
Date:   Thu, 20 Jun 2019 14:31:58 +0100
From:   Daniel Thompson <daniel.thompson@...aro.org>
To:     Marc Gonzalez <marc.w.gonzalez@...e.fr>,
        Lee Jones <lee.jones@...aro.org>,
        Jingoo Han <jingoohan1@...il.com>,
        Bartlomiej Zolnierkiewicz <b.zolnierkie@...sung.com>
Cc:     DRI <dri-devel@...ts.freedesktop.org>,
        fbdev <linux-fbdev@...r.kernel.org>,
        LKML <linux-kernel@...r.kernel.org>,
        Antonino Daplas <adaplas@...il.com>
Subject: Re: [PATCH v1] backlight: Don't build support by default

On 12/06/2019 14:27, Marc Gonzalez wrote:
> b20c5249aa6a ("backlight: Fix compile error if CONFIG_FB is unset")
> added 'default m' for BACKLIGHT_CLASS_DEVICE and LCD_CLASS_DEVICE.

It took me some little while until I realized this patch is from 2005 
which explains why I couldn't find it in the modern git repo!


> Let's go back to not building support by default.

At first glance disabling this by default looks like it would cause some 
existing defconfig files to disable useful drivers.

For backlight I think this isn't true (because both DRM and FB_BACKLIGHT 
have a "select" on BACKLIGHT_CLASS_DEVICE).

However for LCD it is not nearly as clear cut. Commit message needs to 
explain why this won't cause unacceptable problems for existinng 
defconfig files.


Daniel.




> 
> Signed-off-by: Marc Gonzalez <marc.w.gonzalez@...e.fr>
> ---
>   drivers/video/backlight/Kconfig | 2 --
>   1 file changed, 2 deletions(-)
> 
> diff --git a/drivers/video/backlight/Kconfig b/drivers/video/backlight/Kconfig
> index 8b081d61773e..40676be2e46a 100644
> --- a/drivers/video/backlight/Kconfig
> +++ b/drivers/video/backlight/Kconfig
> @@ -10,7 +10,6 @@ menu "Backlight & LCD device support"
>   #
>   config LCD_CLASS_DEVICE
>           tristate "Lowlevel LCD controls"
> -	default m
>   	help
>   	  This framework adds support for low-level control of LCD.
>   	  Some framebuffer devices connect to platform-specific LCD modules
> @@ -143,7 +142,6 @@ endif # LCD_CLASS_DEVICE
>   #
>   config BACKLIGHT_CLASS_DEVICE
>           tristate "Lowlevel Backlight controls"
> -	default m
>   	help
>   	  This framework adds support for low-level control of the LCD
>             backlight. This includes support for brightness and power.
>