[PATCH 3.16 229/328] drm/i915/bdw: Increase IPS disable timeout to 100ms

[Ben Hutchings]

3.16.62-rc1 review patch.  If anyone has any objections, please let me know.

------------------

From: Imre Deak <imre.deak@xxxxxxxxx>

commit 92a6803149465e2339f8f7f8f6415d75be80073d upstream.

During IPS disabling the current 42ms timeout value leads to occasional
timeouts, increase it to 100ms which seems to get rid of the problem.

References: https://bugs.freedesktop.org/show_bug.cgi?id=107494
Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=107562
Reported-by: Diego Viola <diego.viola@xxxxxxxxx>
Tested-by: Diego Viola <diego.viola@xxxxxxxxx>
Cc: Diego Viola <diego.viola@xxxxxxxxx>
Signed-off-by: Imre Deak <imre.deak@xxxxxxxxx>
Reviewed-by: Ville SyrjÃlà <ville.syrjala@xxxxxxxxxxxxxxx>
Link: https://patchwork.freedesktop.org/patch/msgid/20180905100005.7663-1-imre.deak@xxxxxxxxx
(cherry picked from commit acb3ef0ee40ea657280a4a11d9f60eb2937c0dca)
Signed-off-by: Rodrigo Vivi <rodrigo.vivi@xxxxxxxxx>
[bwh: Backported to 3.16: adjust context]
Signed-off-by: Ben Hutchings <ben@xxxxxxxxxxxxxxx>
---
 drivers/gpu/drm/i915/intel_display.c | 8 ++++++--
 1 file changed, 6 insertions(+), 2 deletions(-)

--- a/drivers/gpu/drm/i915/intel_display.c
+++ b/drivers/gpu/drm/i915/intel_display.c
@@ -3794,8 +3794,12 @@ void hsw_disable_ips(struct intel_crtc *
 		mutex_lock(&dev_priv->rps.hw_lock);
 		WARN_ON(sandybridge_pcode_write(dev_priv, DISPLAY_IPS_CONTROL, 0));
 		mutex_unlock(&dev_priv->rps.hw_lock);
-		/* wait for pcode to finish disabling IPS, which may take up to 42ms */
-		if (wait_for((I915_READ(IPS_CTL) & IPS_ENABLE) == 0, 42))
+		/*
+		 * Wait for PCODE to finish disabling IPS. The BSpec specified
+		 * 42ms timeout value leads to occasional timeouts so use 100ms
+		 * instead.
+		 */
+		if (wait_for((I915_READ(IPS_CTL) & IPS_ENABLE) == 0, 100))
 			DRM_ERROR("Timed out waiting for IPS disable\n");
 	} else {
 		I915_WRITE(IPS_CTL, 0);