linux-kernel - Re: [PATCH] drm/kms: fix fbdev blanking regression

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Date:	Wed, 6 Jan 2010 17:33:17 +0000 (GMT)
From:	James Simmons <jsimmons@...radead.org>
To:	Johan Hovold <jhovold@...il.com>
cc:	Dave Airlie <airlied@...hat.com>, dri-devel@...ts.sourceforge.net,
	linux-kernel@...r.kernel.org
Subject: Re: [PATCH] drm/kms: fix fbdev blanking regression


> Commit 731b5a15a3b1474a41c2ca29b4c32b0f21bc852e (drm/kms: properly
> handle fbdev blanking) breaks console blanking on my laptop (GM45
> chipset). Instead of blanking the screen, it is dimmed and then the
> backlight starts "glowing" in the lower edges of the screen. The glowing
> then slowly spreads upwards. Does not look healthy at all...
> 
> This patch reverts to the old behaviour of going directly to
> DPMS_STANDBY.

The current fbdev blank is correct. Normal blanking doesn't power down 
the hsync or the vsync signals. If you look at fbdev drivers you will see 
this type of behavior. If you want a full power down then a FB_BLANK_POWERDOWN 
is needed. As for the blacklight that is a another problem not related to 
this issue. The fbdev layer sends a event to the backlight layer to tell 
it to power down. That powerdown happens for the backlight in all cases 
except FB_BLANK_UNBLANK. How is your backlight setup. Is the backlight 
handled via the DRI driver or acpi?

> Signed-off-by: Johan Hovold <jhovold@...il.com>
> ---
>  drivers/gpu/drm/drm_fb_helper.c |    2 +-
>  1 files changed, 1 insertions(+), 1 deletions(-)
> 
> diff --git a/drivers/gpu/drm/drm_fb_helper.c b/drivers/gpu/drm/drm_fb_helper.c
> index 1b49fa0..9008583 100644
> --- a/drivers/gpu/drm/drm_fb_helper.c
> +++ b/drivers/gpu/drm/drm_fb_helper.c
> @@ -389,7 +389,7 @@ int drm_fb_helper_blank(int blank, struct fb_info *info)
>  		break;
>  	/* Display: Off; HSync: On, VSync: On */
>  	case FB_BLANK_NORMAL:
> -		drm_fb_helper_off(info, DRM_MODE_DPMS_ON);
> +		drm_fb_helper_off(info, DRM_MODE_DPMS_STANDBY);
>  		break;
>  	/* Display: Off; HSync: Off, VSync: On */
>  	case FB_BLANK_HSYNC_SUSPEND:
> -- 
> 1.6.6
> 
> 
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