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path: root/drivers/gpu/drm/i915/intel_i2c.c
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Diffstat (limited to 'drivers/gpu/drm/i915/intel_i2c.c')
-rw-r--r--drivers/gpu/drm/i915/intel_i2c.c25
1 files changed, 21 insertions, 4 deletions
diff --git a/drivers/gpu/drm/i915/intel_i2c.c b/drivers/gpu/drm/i915/intel_i2c.c
index 82d04c5899d..d3b903bce7c 100644
--- a/drivers/gpu/drm/i915/intel_i2c.c
+++ b/drivers/gpu/drm/i915/intel_i2c.c
@@ -259,7 +259,7 @@ gmbus_xfer(struct i2c_adapter *adapter,
if (wait_for(I915_READ(GMBUS2 + reg_offset) & (GMBUS_SATOER | GMBUS_HW_RDY), 50))
goto timeout;
if (I915_READ(GMBUS2 + reg_offset) & GMBUS_SATOER)
- return 0;
+ goto clear_err;
val = I915_READ(GMBUS3 + reg_offset);
do {
@@ -287,7 +287,7 @@ gmbus_xfer(struct i2c_adapter *adapter,
if (wait_for(I915_READ(GMBUS2 + reg_offset) & (GMBUS_SATOER | GMBUS_HW_RDY), 50))
goto timeout;
if (I915_READ(GMBUS2 + reg_offset) & GMBUS_SATOER)
- return 0;
+ goto clear_err;
val = loop = 0;
do {
@@ -302,14 +302,31 @@ gmbus_xfer(struct i2c_adapter *adapter,
if (i + 1 < num && wait_for(I915_READ(GMBUS2 + reg_offset) & (GMBUS_SATOER | GMBUS_HW_WAIT_PHASE), 50))
goto timeout;
if (I915_READ(GMBUS2 + reg_offset) & GMBUS_SATOER)
- return 0;
+ goto clear_err;
}
- return num;
+ goto done;
+
+clear_err:
+ /* Toggle the Software Clear Interrupt bit. This has the effect
+ * of resetting the GMBUS controller and so clearing the
+ * BUS_ERROR raised by the slave's NAK.
+ */
+ I915_WRITE(GMBUS1 + reg_offset, GMBUS_SW_CLR_INT);
+ I915_WRITE(GMBUS1 + reg_offset, 0);
+
+done:
+ /* Mark the GMBUS interface as disabled. We will re-enable it at the
+ * start of the next xfer, till then let it sleep.
+ */
+ I915_WRITE(GMBUS0 + reg_offset, 0);
+ return i;
timeout:
DRM_INFO("GMBUS timed out, falling back to bit banging on pin %d [%s]\n",
bus->reg0 & 0xff, bus->adapter.name);
+ I915_WRITE(GMBUS0 + reg_offset, 0);
+
/* Hardware may not support GMBUS over these pins? Try GPIO bitbanging instead. */
bus->force_bit = intel_gpio_create(dev_priv, bus->reg0 & 0xff);
if (!bus->force_bit)