Save the GMBUS2 value read while polling for state changes, and then
reuse this value when determining for which reason the loops were exited.
This is a small optimization which saves a couple of bus accesses for
memory mapped IO registers.

Signed-off-by: Daniel Kurtz <djkurtz at chromium.org>
Reviewed-by: Chris Wilson <chris at chris-wilson.co.uk>
---
 drivers/gpu/drm/i915/intel_i2c.c |   17 +++++++++--------
 1 files changed, 9 insertions(+), 8 deletions(-)

diff --git a/drivers/gpu/drm/i915/intel_i2c.c b/drivers/gpu/drm/i915/intel_i2c.c
index 9619bde..7674c89 100644
--- a/drivers/gpu/drm/i915/intel_i2c.c
+++ b/drivers/gpu/drm/i915/intel_i2c.c
@@ -214,6 +214,7 @@ gmbus_xfer(struct i2c_adapter *adapter,
        struct drm_i915_private *dev_priv = bus->dev_priv;
        int i, reg_offset;
        int ret = 0;
+       u32 gmbus2 = 0;

        mutex_lock(&dev_priv->gmbus_mutex);

@@ -268,12 +269,12 @@ gmbus_xfer(struct i2c_adapter *adapter,
                        do {
                                u32 val, loop = 0;

-                               if (wait_for(I915_READ(GMBUS2 + reg_offset) &
+                               if (wait_for((gmbus2 = I915_READ(GMBUS2 +
+                                                                reg_offset)) &
                                             (GMBUS_SATOER | GMBUS_HW_RDY),
                                             50))
                                        goto timeout;
-                               if (I915_READ(GMBUS2 + reg_offset) &
-                                   GMBUS_SATOER)
+                               if (gmbus2 & GMBUS_SATOER)
                                        goto clear_err;

                                val = I915_READ(GMBUS3 + reg_offset);
@@ -308,21 +309,21 @@ gmbus_xfer(struct i2c_adapter *adapter,
                                I915_WRITE(GMBUS3 + reg_offset, val);
                                POSTING_READ(GMBUS2 + reg_offset);

-                               if (wait_for(I915_READ(GMBUS2 + reg_offset) &
+                               if (wait_for((gmbus2 = I915_READ(GMBUS2 +
+                                                                reg_offset)) &
                                             (GMBUS_SATOER | GMBUS_HW_RDY),
                                             50))
                                        goto timeout;
-                               if (I915_READ(GMBUS2 + reg_offset) &
-                                   GMBUS_SATOER)
+                               if (gmbus2 & GMBUS_SATOER)
                                        goto clear_err;
                        }
                }

-               if (wait_for(I915_READ(GMBUS2 + reg_offset) &
+               if (wait_for((gmbus2 = I915_READ(GMBUS2 + reg_offset)) &
                             (GMBUS_SATOER | GMBUS_HW_WAIT_PHASE),
                             50))
                        goto timeout;
-               if (I915_READ(GMBUS2 + reg_offset) & GMBUS_SATOER)
+               if (gmbus2 & GMBUS_SATOER)
                        goto clear_err;
        }

-- 
1.7.7.3

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