Re: LCD: fix oops if driver only interested in .set_power

[Ben Dooks <ben-linux@fluff.org>]

On Tue, Nov 18, 2008 at 06:03:50PM +0000, Ben Dooks wrote:
> The LCD driver core calls LCD drivers when either the
> blanking state or the display mode has changed, but
> does not make any check to see if the called driver
> has a .set_mode method.
> 
> This means if a driver only has a .set_power method
> then the system will OOPS on changing mode (and with
> the console semaphore held so you cannot easily see
> the problem).
> 
> Fix the problem by ensuring that either callback is
> valid before calling it.
> 
> Signed-off-by: Ben Dooks <ben-linux@fluff.org>
> Index: linux.git/drivers/video/backlight/lcd.c
> ===================================================================
> --- linux.git.orig/drivers/video/backlight/lcd.c	2008-11-18 12:59:21.000000000 +0000
> +++ linux.git/drivers/video/backlight/lcd.c	2008-11-18 15:07:25.000000000 +0000
> @@ -43,9 +43,11 @@ static int fb_notifier_callback(struct n
>  	mutex_lock(&ld->ops_lock);
>  	if (!ld->ops->check_fb || ld->ops->check_fb(ld, evdata->info)) {
>  		if (event == FB_EVENT_BLANK)
> -			ld->ops->set_power(ld, *(int *)evdata->data);
> +			if (ld->ops->set_power)
> +				ld->ops->set_power(ld, *(int *)evdata->data);
>  		else

sorry, needed to put {} around the outer if block to keep gcc
happy.

> -			ld->ops->set_mode(ld, evdata->data);
> +			if (ld->ops->set_mode)
> +				ld->ops->set_mode(ld, evdata->data);
>  	}
>  	mutex_unlock(&ld->ops_lock);
>  	return 0;
> 
> -- 
> Ben (ben@fluff.org, http://www.fluff.org/)
> 
>   'a smiley only costs 4 bytes'
> 
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-- 
Ben (ben@fluff.org, http://www.fluff.org/)

  'a smiley only costs 4 bytes'

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