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

[Johan Hovold <jhovold@gmail.com>]

> > 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?
> 

The change itself looks correct but it triggers something that seems to
hurt my screen bad. :)

The backlight is handled via the DRI driver I assume. At least
i9xx_crtc_dpms is called on powerdown.