[Precise][SRU][PATCH 1/1] drm/i915: Periodically sanity check power management

Seth Forshee seth.forshee at canonical.com
Thu Mar 7 20:46:08 UTC 2013


On Thu, Mar 07, 2013 at 12:14:55PM -0800, leann.ogasawara at canonical.com wrote:
> From: Chris Wilson <chris at chris-wilson.co.uk>
> 
> BugLink: http://bugs.launchpad.net/bugs/1146425
> 
> Every time we use the device after a period of idleness, check that the
> power management setup is still sane. This is to workaround a bug
> whereby it seems that we begin suppressing power management interrupts,
> preventing SandyBridge+ from going into turbo mode.
> 
> This patch does have a side-effect. It removes the mark-busy for just
> moving the cursor - we don't want to increase the render clock just for
> the sprite, though we may want to bump the display frequency. I'd argue
> that we do not, and certainly don't want to take the struct_mutex here
> due to the large latencies that introduces.

Regarding this last paragraph: The upstream commit does remove a call to
intel_mark_busy() from intel_crtc_update_cursor(), which I suspect is
what this refers to. That call is present in our precise kernel but is
not removed by this patch. Do you know whether or not that omission was
intentional?

Seth




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