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 <[email protected]> know about it.


>From ee0a227b7ac6e75f28e10269f81c7ec6eb600952 Mon Sep 17 00:00:00 2001
From: Chris Wilson <[email protected]>
Date: Wed, 15 Jul 2015 09:50:42 +0100
Subject: drm/i915: Replace WARN inside I915_READ64_2x32 with retry loop
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 8bit

From: Chris Wilson <[email protected]>

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 <[email protected]>
Cc: MichaƂ Winiarski <[email protected]>
Signed-off-by: Daniel Vetter <[email protected]>
Signed-off-by: Greg Kroah-Hartman <[email protected]>

---
 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 [email protected] 
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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