linux-kernel - Re: [resend] i915: high power consumption after suspend/resume

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Date:	Mon, 5 Oct 2009 09:21:48 -0700
From:	Jesse Barnes <jbarnes@...tuousgeek.org>
To:	Andrew Lutomirski <luto@....edu>
Cc:	intel-gfx@...ts.freedesktop.org, linux-kernel@...r.kernel.org,
	dri-devel@...ts.sf.net
Subject: Re: [resend] i915: high power consumption after suspend/resume

On Sat, 3 Oct 2009 12:50:01 -0400
Andrew Lutomirski <luto@....edu> wrote:

> [resend b/c the intel-gfx list doesn't allow non-member posting]
> 
> Hi-
> 
> First, thanks for all the great work on i915's power saving features
> -- power consumption on my laptop (Lenovo X200s) is now almost as low
> on Linux as on Windows.
> 
> After a suspend/resume cycle, though, my power consumption usually
> goes up by over a watt.  I think this is due to i915, because of an
> experiment I did:
> 
> 1. Boot with modesetting off into single user mode.
> 2. Suspend and resume
> 3. Reload i915 with modesetting on.  Power consumption is low.
> 4. Suspend and resume.  Power consumption is high.
> 5. Unbind and rebind i915.  Power consumption is high.
> 6. Suspend.  System hangs (seperate bug, I guess).
> 
> I get similar results if I boot single user with modesetting on: power
> consumption is low, becomes high after suspend/resume, and goes low
> again after rebinding i915.
> 
> This is on 2.6.32-rc1 + a little (i.e. 84d88d5d4e from Linus' tree
> plus an ext4 fix).  I'm having trouble reproducing any of this on
> 2.6.31.

I probably need to save/restore some more of the power saving state
across suspend/resume...  Can you file a bug for this at
bugs.freedesktop.org so it doesn't get lost?

Thanks,
-- 
Jesse Barnes, Intel Open Source Technology Center
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