[Intel-gfx] [RFT] drm/i915: enable/disable LVDS port at DPMS time
jbarnes at virtuousgeek.org
Thu Feb 11 17:44:36 PST 2010
On Fri, 12 Feb 2010 09:26:28 +0800
ykzhao <yakui.zhao at intel.com> wrote:
> On Fri, 2010-02-12 at 04:41 +0800, Jesse Barnes wrote:
> > It would be good to disable the LVDS port when we shut down the
> > panel to save power. We haven't done so until now because we had
> > trouble getting the right LVDS parameters from the BIOS. I think
> > we're past that now, so enabling and disabling the port should be
> > safe, though it would probably be made cleaner with some additional
> > changes to the display code, where we also bang on the LVDS reg to
> > set the pairing correctly etc.
> > Seems to save a bit of power (up to 300mW in my basic wattsup
> > meter testing).
> Hi, Jesse
> Do you test it on the laptop based on Ironlake or
> crestline/cantiga platform?
> On the ironlake the LVDS_PORT_EN bit will be enabled/disabled in
> course of CRTC DPMS.
> >From the spec this bit must be set before the display PLL is
Ah right, looks like on Ironlake we disable it there too, so this patch
isn't needed on Ironlake and above.
Jesse Barnes, Intel Open Source Technology Center
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