On Thursday 18 September 2014 02:09 PM, Ville Syrjälä wrote:
On Thu, Sep 18, 2014 at 06:51:50PM +0530, [email protected] wrote:
From: Deepak S <[email protected]>

Based on the HW team inputs. We can should not wait for the old ack,
Waiting for old ack might fail, when other forcewake came before the
present one is desserted.

for example, if forcewake bit 0 was set and before it could get cleared
forcewake bit 1 got set, HW eventually clear bit 0, when the bit 1
is cleared. i.e, bit 1 is still sent then forcewake bit 0 will still be
set.

Signed-off-by: Deepak S <[email protected]>
---
  drivers/gpu/drm/i915/intel_uncore.c | 10 ----------
  1 file changed, 10 deletions(-)

diff --git a/drivers/gpu/drm/i915/intel_uncore.c 
b/drivers/gpu/drm/i915/intel_uncore.c
index 918b761..bcb0806 100644
--- a/drivers/gpu/drm/i915/intel_uncore.c
+++ b/drivers/gpu/drm/i915/intel_uncore.c
@@ -196,11 +196,6 @@ static void __vlv_force_wake_get(struct drm_i915_private 
*dev_priv,
  {
        /* Check for Render Engine */
        if (FORCEWAKE_RENDER & fw_engine) {
-               if (wait_for_atomic((__raw_i915_read32(dev_priv,
-                                               FORCEWAKE_ACK_VLV) &
-                                               FORCEWAKE_KERNEL) == 0,
-                                       FORCEWAKE_ACK_TIMEOUT_MS))
-                       DRM_ERROR("Timed out: Render forcewake old ack to 
clear.\n");
Can we have a comment here? Something like this perhaps:

/*
  * WaRsDontPollForAckOnClearingFWBits:vlv
  * Hardware clears ack bits lazily (only when all ack
  * bits become 0) so don't poll for individiual ack
  * bits to be clear here.
  */

Apart from that:
Reviewed-by: Ville Syrjälä <[email protected]>

Thanks Ville, I will change the commit message.

                __raw_i915_write32(dev_priv, FORCEWAKE_VLV,
                                   _MASKED_BIT_ENABLE(FORCEWAKE_KERNEL));
@@ -214,11 +209,6 @@ static void __vlv_force_wake_get(struct drm_i915_private 
*dev_priv,
/* Check for Media Engine */
        if (FORCEWAKE_MEDIA & fw_engine) {
-               if (wait_for_atomic((__raw_i915_read32(dev_priv,
-                                               FORCEWAKE_ACK_MEDIA_VLV) &
-                                               FORCEWAKE_KERNEL) == 0,
-                                       FORCEWAKE_ACK_TIMEOUT_MS))
-                       DRM_ERROR("Timed out: Media forcewake old ack to 
clear.\n");
__raw_i915_write32(dev_priv, FORCEWAKE_MEDIA_VLV,
                                   _MASKED_BIT_ENABLE(FORCEWAKE_KERNEL));
--
1.9.1

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