CHROMIUM: drm/i915: Adjust the down threshold.

Commit Message

James Ausmus Aug. 16, 2013, 12:30 a.m. UTC

From: Stéphane Marchesin <[e-mail]>

The thresholds for GPU reclocking are highly asymetrical. This creates an
interesting phenomenon on Chrome startup where the clock ramps up very
quickly, and then the blinking cursor is enough to keep it up. Obviously
having the max GPU clock on the login screen is very bad for thermals.

With this change, the clock goes back to its minimum frequency after a couple
of seconds.

BUG=chrome-os-partner:11009
TEST=checked that a blinking cursor lets the GPU clock go back to 350Mhz

Change-Id: I3b8de74864907abdb3c7c4aeb0ab4fcf2eaf0b2c
Reviewed-on: https://gerrit.chromium.org/gerrit/26641
Tested-by: Stéphane Marchesin <[e-mail]>
Reviewed-by: Sean Paul <[e-mail]>
Reviewed-by: Sameer Nanda <[e-mail]>
Commit-Ready: Stéphane Marchesin <[e-mail]>
[marcheu: Fixups for 3.8]
Signed-off-by: Stéphane Marchesin <[e-mail]>
---
 drivers/gpu/drm/i915/intel_pm.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

Comments

Chris Wilson Aug. 16, 2013, 7:58 a.m. UTC | #1

On Thu, Aug 15, 2013 at 05:30:40PM -0700, [e-mail] wrote:
> From: Stéphane Marchesin <[e-mail]>
> 
> The thresholds for GPU reclocking are highly asymetrical. This creates an
> interesting phenomenon on Chrome startup where the clock ramps up very
> quickly, and then the blinking cursor is enough to keep it up. Obviously
> having the max GPU clock on the login screen is very bad for thermals.
> 
> With this change, the clock goes back to its minimum frequency after a couple
> of seconds.

You can drop the RPS changes as Stéphane has been feeding these back
once he found (semi?) stable values.
-Chris

Patch

diff --git a/drivers/gpu/drm/i915/intel_pm.c b/drivers/gpu/drm/i915/intel_pm.c
index 3280cff..6d5e3ed 100644
--- a/drivers/gpu/drm/i915/intel_pm.c
+++ b/drivers/gpu/drm/i915/intel_pm.c
@@ -2612,7 +2612,7 @@  static void gen6_enable_rps(struct drm_device *dev)
 		   dev_priv->rps.min_delay << 16);
 
 	I915_WRITE(GEN6_RP_UP_THRESHOLD, 59400);
-	I915_WRITE(GEN6_RP_DOWN_THRESHOLD, 245000);
+	I915_WRITE(GEN6_RP_DOWN_THRESHOLD, 100000);
 	I915_WRITE(GEN6_RP_UP_EI, 66000);
 	I915_WRITE(GEN6_RP_DOWN_EI, 350000);