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

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Message-ID: <alpine.LFD.2.00.1001121645570.9778@casper.infradead.org>
Date:	Tue, 12 Jan 2010 17:28:33 +0000 (GMT)
From:	James Simmons <jsimmons@...radead.org>
To:	David John <davidjon@...ontk.org>
cc:	Johan Hovold <jhovold@...il.com>, Dave Airlie <airlied@...hat.com>,
	dri-devel@...ts.sourceforge.net, linux-kernel@...r.kernel.org,
	Eric Anholt <eric@...olt.net>,
	Jesse Barnes <jbarnes@...tuousgeek.org>
Subject: Re: [PATCH] drm/kms: fix fbdev blanking regression

> On 01/07/2010 12:42 AM, Johan Hovold wrote:
> >> Yeap. The fix uncovered a bug in your driver. I haven't heard of problems 
> >> with the other drm drivers.
> >>  
> >>> The backlight is handled via the DRI driver I assume. At least
> >>> i9xx_crtc_dpms is called on powerdown.
> >>
> >> Can you post your dmesg and kernel config.
> 
> [snip]
> 
> Adding the Intel DRM people in CC as well. I have the same issue with my
> GM45.

Okay I looked at the code to figure out what is happening and why only 
this driver has problems. The problem is that the framebuffer layer 
expects the backlight to be a seperate device. The reason being is that
some embedded systems will use a gpio backlight. That way power management 
for a graphics card/backlight has 3 seperate states. Currently the intel 
DRM driver treats the backlight as being apart of the encoder. Jesse do 
you have objections to having the intel driver expose a backlight device.
The bonus of that is the user can also set the backlight levels.

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