From: Chris Wilson <chris@xxxxxxxxxxxxxxxxxx>
This patch has been added to the 3.18 stable tree. If you have any
objections, please let us know.
===============
[ Upstream commit ee0a227b7ac6e75f28e10269f81c7ec6eb600952 ]
Since we may conceivably encounter situations where the upper part of the
64bit register changes between reads, for example when a timestamp
counter overflows, change the WARN into a retry loop.
Signed-off-by: Chris Wilson <chris@xxxxxxxxxxxxxxxxxx>
Cc: Michał Winiarski <michal.winiarski@xxxxxxxxx>
Cc: stable@xxxxxxxxxxxxxxx
Signed-off-by: Daniel Vetter <daniel.vetter@xxxxxxxx>
Signed-off-by: Sasha Levin <sasha.levin@xxxxxxxxxx>
---
drivers/gpu/drm/i915/i915_drv.h | 17 ++++++++---------
1 file changed, 8 insertions(+), 9 deletions(-)
diff --git a/drivers/gpu/drm/i915/i915_drv.h b/drivers/gpu/drm/i915/i915_drv.h
index a849713..c68e9f2 100644
--- a/drivers/gpu/drm/i915/i915_drv.h
+++ b/drivers/gpu/drm/i915/i915_drv.h
@@ -2899,15 +2899,14 @@ int vlv_freq_opcode(struct drm_i915_private *dev_priv, int val);
#define I915_READ64(reg) dev_priv->uncore.funcs.mmio_readq(dev_priv, (reg), true)
#define I915_READ64_2x32(lower_reg, upper_reg) ({ \
- u32 upper = I915_READ(upper_reg); \
- u32 lower = I915_READ(lower_reg); \
- u32 tmp = I915_READ(upper_reg); \
- if (upper != tmp) { \
- upper = tmp; \
- lower = I915_READ(lower_reg); \
- WARN_ON(I915_READ(upper_reg) != upper); \
- } \
- (u64)upper << 32 | lower; })
+ u32 upper, lower, tmp; \
+ tmp = I915_READ(upper_reg); \
+ do { \
+ upper = tmp; \
+ lower = I915_READ(lower_reg); \
+ tmp = I915_READ(upper_reg); \
+ } while (upper != tmp); \
+ (u64)upper << 32 | lower; })
#define POSTING_READ(reg) (void)I915_READ_NOTRACE(reg)
#define POSTING_READ16(reg) (void)I915_READ16_NOTRACE(reg)
--
2.1.4
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