On Fri, Aug 24, 2012 at 12:31:11PM -0700, Ben Widawsky wrote:
The same designer from the previous patch has told us to never read
FORCEWAKE. We only do this for the POSTING_READ(), so simply change that
to something within the same cacheline (for no reason in particular
other than it sounds nice). In the _mt case we can leverage
the gtfifodbg check for the POSTING_READ.
Signed-off-by: Ben Widawsky b...@bwidawsk.net
This partially reverts
commit 6af2d180f82151cf3d58952e35a4f96e45bc453a
Author: Daniel Vetter daniel.vet...@ffwll.ch
Date: Thu Jul 26 16:24:50 2012 +0200
drm/i915: fix forcewake related hangs on snb
I guess the commit message should mention that. Also, please add a comment
it the _put functions that the check_fifodbg serves as a posting read (and
that we have experimental evidence suggesting that we should readback
something nearby).
btw, can you please ask your nice designer whether he has any clue whether
that nearby posting_read has an effect?
Thanks, Daniel
---
drivers/gpu/drm/i915/intel_pm.c | 6 ++
1 file changed, 2 insertions(+), 4 deletions(-)
diff --git a/drivers/gpu/drm/i915/intel_pm.c b/drivers/gpu/drm/i915/intel_pm.c
index 2a8468d..83ec02c 100644
--- a/drivers/gpu/drm/i915/intel_pm.c
+++ b/drivers/gpu/drm/i915/intel_pm.c
@@ -3975,7 +3975,7 @@ static void __gen6_gt_force_wake_get(struct
drm_i915_private *dev_priv)
DRM_ERROR(Force wake wait timed out\n);
I915_WRITE_NOTRACE(FORCEWAKE, 1);
- POSTING_READ(FORCEWAKE);
+ POSTING_READ(ECOBUS); /* something from same cacheline, but !FORCEWAKE
*/
if (wait_for_atomic((I915_READ_NOTRACE(forcewake_ack) 1),
FORCEWAKE_ACK_TIMEOUT_MS))
@@ -3998,7 +3998,7 @@ static void __gen6_gt_force_wake_mt_get(struct
drm_i915_private *dev_priv)
DRM_ERROR(Force wake wait timed out\n);
I915_WRITE_NOTRACE(FORCEWAKE_MT, _MASKED_BIT_ENABLE(1));
- POSTING_READ(FORCEWAKE_MT);
+ POSTING_READ(ECOBUS); /* something from same cacheline, but !FORCEWAKE
*/
if (wait_for_atomic((I915_READ_NOTRACE(forcewake_ack) 1),
FORCEWAKE_ACK_TIMEOUT_MS))
@@ -4035,14 +4035,12 @@ void gen6_gt_check_fifodbg(struct drm_i915_private
*dev_priv)
static void __gen6_gt_force_wake_put(struct drm_i915_private *dev_priv)
{
I915_WRITE_NOTRACE(FORCEWAKE, 0);
- POSTING_READ(FORCEWAKE);
gen6_gt_check_fifodbg(dev_priv);
}
static void __gen6_gt_force_wake_mt_put(struct drm_i915_private *dev_priv)
{
I915_WRITE_NOTRACE(FORCEWAKE_MT, _MASKED_BIT_DISABLE(1));
- POSTING_READ(FORCEWAKE_MT);
gen6_gt_check_fifodbg(dev_priv);
}
--
1.7.12
___
Intel-gfx mailing list
Intel-gfx@lists.freedesktop.org
http://lists.freedesktop.org/mailman/listinfo/intel-gfx
--
Daniel Vetter
Mail: dan...@ffwll.ch
Mobile: +41 (0)79 365 57 48
___
Intel-gfx mailing list
Intel-gfx@lists.freedesktop.org
http://lists.freedesktop.org/mailman/listinfo/intel-gfx
