Merge branch 'drm-fixes' of git://people.freedesktop.org/~airlied/linux

Pull drm fixes from Dave Airlie:
 "Just regular fixes, bunch from intel, quieting some of the over
  zealous power warnings, and the rest just misc.

  I've got another pull with the remaining dma-buf bits, since the vmap
  bits are in your tree now.  I'll send tomorrow just to space things
  out a bit."

* 'drm-fixes' of git://people.freedesktop.org/~airlied/linux: (22 commits)
  drm/edid/quirks: ViewSonic VA2026w
  drm/udl: remove unused variables.
  drm/radeon: fix XFX quirk
  drm: Use stdint types for consistency
  drm: Constify params to format_check() and framebuffer_checks()
  drm/radeon: fix typo in trinity tiling setup
  drm/udl: unlock before returning in udl_gem_mmap()
  radeon: make radeon_cs_update_pages static.
  drm/i915: tune down the noise of the RP irq limit fail
  drm/i915: Remove the error message for unbinding pinned buffers
  drm/i915: Limit page allocations to lowmem (dma32) for i965
  drm/i915: always use RPNSWREQ for turbo change requests
  drm/i915: reject doubleclocked cea modes on dp
  drm/i915: Adding TV Out Missing modes.
  drm/i915: wait for a vblank to pass after tv detect
  drm/i915: no lvds quirk for HP t5740e Thin Client
  drm/i915: enable vdd when switching off the eDP panel
  drm/i915: Fix PCH PLL assertions to not assume CRTC:PLL relationship
  drm/i915: Always update RPS interrupts thresholds along with frequency
  drm/i915: properly handle interlaced bit for sdvo dtd conversion
  ...

1 files changed, 12 insertions, 9 deletions

diff --git a/drivers/gpu/drm/i915/intel_i2c.c b/drivers/gpu/drm/i915/intel_i2c.c
index 4a9707dd0f9..1991a4408cf 100644
--- 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: