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

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Message-ID: <a728f9f91001131201k6ba53710jdf85c1e38a937901@mail.gmail.com>
Date:	Wed, 13 Jan 2010 15:01:00 -0500
From:	Alex Deucher <alexdeucher@...il.com>
To:	James Simmons <jsimmons@...radead.org>
Cc:	Jesse Barnes <jbarnes@...tuousgeek.org>,
	David John <davidjon@...ontk.org>,
	Johan Hovold <jhovold@...il.com>, linux-kernel@...r.kernel.org,
	Dave Airlie <airlied@...hat.com>,
	dri-devel@...ts.sourceforge.net
Subject: Re: [PATCH] drm/kms: fix fbdev blanking regression

On Wed, Jan 13, 2010 at 2:48 PM, James Simmons <jsimmons@...radead.org> wrote:
>
>> > > 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.
>>
>> On Intel we usually expect the backlight to be exposed by ACPI or a
>> platform driver.  On recent platforms, the ACPI driver will actually
>> send requests to the gfx driver to do the actual register writes to
>> adjust the backlight, but it's still ACPI driven.
>>
>> Maybe we just need to wire up the fb backlight hooks appropriately?
>
> Yeap. I can have patch ready for you this weekend. I lack the hardware to
> test it tho. Never been able to find a intel pci card that is not built
> into the motherboard.

They don't exist, other than the old i740s.

Alex
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