drm/i915: align vlv forcewake with common lore

For some odd reasons, the vlv forcewake code is rather different from
all other platforms, with no clear justification. Adjust things:

- Don't check whether the gt is awake already (and bail out early), we
  need to grab a forcewake anyway. Otherwise the chip might go to
  sleep too early. And this would also screw up our forcewake
  accounting.
- Like all other platforms, check whether the gt has cleared the
  forcewake bit in the _ACK register before setting it again.
- Use _MASKED_BIT_ENABLE/DISABLE macros
- Only use bit0 of the forcewake reg, not all 16 bits.
- check the gtfifodb reg like on all other platforms in _put.
- Drop the POSTING_READs for consistency.

v2: Failure to git add ... again.

v3: Fixup the spelling fail a bit.

Tested-by: "Purushothaman, Vijay A" <vijay.a.purushothaman@intel.com>
Tested-by: "Widawsky, Benjamin" <benjamin.widawsky@intel.com>
Signed-Off-by: Daniel Vetter <daniel.vetter@ffwll.ch>

1 files changed, 6 insertions, 8 deletions

diff --git a/drivers/gpu/drm/i915/intel_pm.c b/drivers/gpu/drm/i915/intel_pm.c
index 7ae35821121..82f74f36d55 100644
--- a/drivers/gpu/drm/i915/intel_pm.c
+++ b/drivers/gpu/drm/i915/intel_pm.c
@@ -4069,12 +4069,10 @@ int __gen6_gt_wait_for_fifo(struct drm_i915_private *dev_priv)
 
 static void vlv_force_wake_get(struct drm_i915_private *dev_priv)
 {
-        /* Already awake? */
-        if ((I915_READ(0x130094) & 0xa1) == 0xa1)
-                return;
+        if (wait_for_atomic_us((I915_READ_NOTRACE(FORCEWAKE_ACK_VLV) & 1) == 0, 500))
+                DRM_ERROR("Force wake wait timed out\n");
 
-        I915_WRITE_NOTRACE(FORCEWAKE_VLV, 0xffffffff);
-        POSTING_READ(FORCEWAKE_VLV);
+        I915_WRITE_NOTRACE(FORCEWAKE_VLV, _MASKED_BIT_ENABLE(1));
 
         if (wait_for_atomic_us((I915_READ_NOTRACE(FORCEWAKE_ACK_VLV) & 1), 500))
                 DRM_ERROR("Force wake wait timed out\n");
@@ -4084,9 +4082,9 @@ static void vlv_force_wake_get(struct drm_i915_private *dev_priv)
 
 static void vlv_force_wake_put(struct drm_i915_private *dev_priv)
 {
-        I915_WRITE_NOTRACE(FORCEWAKE_VLV, 0xffff0000);
-        /* FIXME: confirm VLV behavior with Punit folks */
-        POSTING_READ(FORCEWAKE_VLV);
+        I915_WRITE_NOTRACE(FORCEWAKE_VLV, _MASKED_BIT_DISABLE(1));
+        /* The below doubles as a POSTING_READ */
+        gen6_gt_check_fifodbg(dev_priv);
 }
 
 void intel_gt_init(struct drm_device *dev)