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drm/i915/intel_i2c: reuse GMBUS2 value read in polling loop

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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.

To avoid "assigning in if clause" checkpatch errors", use a ret variable
to store the wait_for macro return value.

Signed-off-by: Daniel Kurtz <djkurtz@chromium.org>
Reviewed-by: Chris Wilson <chris@chris-wilson.co.uk>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>
This commit is contained in:
Daniel Kurtz 2012-03-30 19:46:41 +08:00 committed by Daniel Vetter
parent 56f9eac054
commit 90e6b26d6b
1 changed files with 22 additions and 12 deletions
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34
drivers/gpu/drm/i915/intel_i2c.c
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@ -219,13 +219,16 @@ gmbus_xfer_read(struct drm_i915_private *dev_priv, struct i2c_msg *msg,
GMBUS_SLAVE_READ | GMBUS_SW_RDY);
POSTING_READ(GMBUS2 + reg_offset);
do {
int ret;
u32 val, loop = 0;
u32 gmbus2;
if (wait_for(I915_READ(GMBUS2 + reg_offset) &
(GMBUS_SATOER | GMBUS_HW_RDY),
50))
ret = wait_for((gmbus2 = I915_READ(GMBUS2 + reg_offset)) &
(GMBUS_SATOER | GMBUS_HW_RDY),
50);
if (ret)
return -ETIMEDOUT;
if (I915_READ(GMBUS2 + reg_offset) & GMBUS_SATOER)
if (gmbus2 & GMBUS_SATOER)
return -ENXIO;
val = I915_READ(GMBUS3 + reg_offset);
@ -260,6 +263,9 @@ gmbus_xfer_write(struct drm_i915_private *dev_priv, struct i2c_msg *msg)
GMBUS_SLAVE_WRITE | GMBUS_SW_RDY);
POSTING_READ(GMBUS2 + reg_offset);
while (len) {
int ret;
u32 gmbus2;
val = loop = 0;
do {
val |= *buf++ << (8 * loop);
@ -268,11 +274,12 @@ gmbus_xfer_write(struct drm_i915_private *dev_priv, struct i2c_msg *msg)
I915_WRITE(GMBUS3 + reg_offset, val);
POSTING_READ(GMBUS2 + reg_offset);
if (wait_for(I915_READ(GMBUS2 + reg_offset) &
(GMBUS_SATOER | GMBUS_HW_RDY),
50))
ret = wait_for((gmbus2 = I915_READ(GMBUS2 + reg_offset)) &
(GMBUS_SATOER | GMBUS_HW_RDY),
50);
if (ret)
return -ETIMEDOUT;
if (I915_READ(GMBUS2 + reg_offset) & GMBUS_SATOER)
if (gmbus2 & GMBUS_SATOER)
return -ENXIO;
}
return 0;
@ -342,6 +349,8 @@ gmbus_xfer(struct i2c_adapter *adapter,
I915_WRITE(GMBUS0 + reg_offset, bus->reg0);
for (i = 0; i < num; i++) {
u32 gmbus2;
if (gmbus_is_index_read(msgs, i, num)) {
ret = gmbus_xfer_index_read(dev_priv, &msgs[i]);
i += 1; /* set i to the index of the read xfer */
@ -356,11 +365,12 @@ gmbus_xfer(struct i2c_adapter *adapter,
if (ret == -ENXIO)
goto clear_err;
if (wait_for(I915_READ(GMBUS2 + reg_offset) &
(GMBUS_SATOER | GMBUS_HW_WAIT_PHASE),
50))
ret = wait_for((gmbus2 = I915_READ(GMBUS2 + reg_offset)) &
(GMBUS_SATOER | GMBUS_HW_WAIT_PHASE),
50);
if (ret)
goto timeout;
if (I915_READ(GMBUS2 + reg_offset) & GMBUS_SATOER)
if (gmbus2 & GMBUS_SATOER)
goto clear_err;
}