This is a note to let you know that I've just added the patch titled
drm/i915: Replace WARN inside I915_READ64_2x32 with retry loop
to the 4.1-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
drm-i915-replace-warn-inside-i915_read64_2x32-with-retry-loop.patch
and it can be found in the queue-4.1 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
>From ee0a227b7ac6e75f28e10269f81c7ec6eb600952 Mon Sep 17 00:00:00 2001
From: Chris Wilson <chris@xxxxxxxxxxxxxxxxxx>
Date: Wed, 15 Jul 2015 09:50:42 +0100
Subject: drm/i915: Replace WARN inside I915_READ64_2x32 with retry loop
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From: Chris Wilson <chris@xxxxxxxxxxxxxxxxxx>
commit ee0a227b7ac6e75f28e10269f81c7ec6eb600952 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: Chris Wilson <chris@xxxxxxxxxxxxxxxxxx>
Cc: Michał Winiarski <michal.winiarski@xxxxxxxxx>
Signed-off-by: Daniel Vetter <daniel.vetter@xxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
drivers/gpu/drm/i915/i915_drv.h | 17 ++++++++---------
1 file changed, 8 insertions(+), 9 deletions(-)
--- a/drivers/gpu/drm/i915/i915_drv.h
+++ b/drivers/gpu/drm/i915/i915_drv.h
@@ -3190,15 +3190,14 @@ int intel_freq_opcode(struct drm_i915_pr
#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)
Patches currently in stable-queue which might be from chris@xxxxxxxxxxxxxxxxxx are
queue-4.1/drm-i915-declare-the-swizzling-unknown-for-l-shaped-configurations.patch
queue-4.1/drm-i915-replace-warn-inside-i915_read64_2x32-with-retry-loop.patch
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