i915: Remove silly test

[android-x86/kernel.git] / drivers / gpu / drm / i915 / intel_i2c.c

diff --git a/drivers/gpu/drm/i915/intel_i2c.c b/drivers/gpu/drm/i915/intel_i2c.c
index 4a9707d..d79500b 100644 (file)
--- a/drivers/gpu/drm/i915/intel_i2c.c
+++ b/drivers/gpu/drm/i915/intel_i2c.c
@@ -396,11 +396,22 @@ clear_err:
         * Wait for bus to IDLE before clearing NAK.
         * If we clear the NAK while bus is still active, then it will stay
         * active and the next transaction may fail.
+        *
+        * If no ACK is received during the address phase of a transaction, the
+        * adapter must report -ENXIO. It is not clear what to return if no ACK
+        * is received at other times. But we have to be careful to not return
+        * spurious -ENXIO because that will prevent i2c and drm edid functions
+        * from retrying. So return -ENXIO only when gmbus properly quiescents -
+        * timing out seems to happen when there _is_ a ddc chip present, but
+        * it's slow responding and only answers on the 2nd retry.
         */
+       ret = -ENXIO;
        if (wait_for((I915_READ(GMBUS2 + reg_offset) & GMBUS_ACTIVE) == 0,
-                    10))
+                    10)) {
                DRM_DEBUG_KMS("GMBUS [%s] timed out after NAK\n",
                              adapter->name);
+               ret = -ETIMEDOUT;
+       }
 
        /* Toggle the Software Clear Interrupt bit. This has the effect
         * of resetting the GMBUS controller and so clearing the
@@ -414,14 +425,6 @@ clear_err:
                         adapter->name, msgs[i].addr,
                         (msgs[i].flags & I2C_M_RD) ? 'r' : 'w', msgs[i].len);
 
-       /*
-        * If no ACK is received during the address phase of a transaction,
-        * the adapter must report -ENXIO.
-        * It is not clear what to return if no ACK is received at other times.
-        * So, we always return -ENXIO in all NAK cases, to ensure we send
-        * it at least during the one case that is specified.
-        */
-       ret = -ENXIO;
        goto out;
 
 timeout:
@@ -537,9 +540,6 @@ void intel_teardown_gmbus(struct drm_device *dev)
        struct drm_i915_private *dev_priv = dev->dev_private;
        int i;
 
-       if (dev_priv->gmbus == NULL)
-               return;
-
        for (i = 0; i < GMBUS_NUM_PORTS; i++) {
                struct intel_gmbus *bus = &dev_priv->gmbus[i];
                i2c_del_adapter(&bus->adapter);