Commit a38baaad authored by Chris Wilson's avatar Chris Wilson Committed by Luis Henriques

drm/i915: Replace WARN inside I915_READ64_2x32 with retry loop

commit ee0a227b upstream.

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: default avatarChris Wilson <chris@chris-wilson.co.uk>
Cc: Michał Winiarski <michal.winiarski@intel.com>
Signed-off-by: default avatarDaniel Vetter <daniel.vetter@ffwll.ch>
Signed-off-by: default avatarLuis Henriques <luis.henriques@canonical.com>
parent 8e5ad4f5
......@@ -2682,14 +2682,13 @@ 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) { \
u32 upper, lower, tmp; \
tmp = I915_READ(upper_reg); \
do { \
upper = tmp; \
lower = I915_READ(lower_reg); \
WARN_ON(I915_READ(upper_reg) != upper); \
} \
tmp = I915_READ(upper_reg); \
} while (upper != tmp); \
(u64)upper << 32 | lower; })
#define POSTING_READ(reg) (void)I915_READ_NOTRACE(reg)
......
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