drm/i915: Actually retry with bit-banging after GMBUS timeout

vsyrjala · jnikula · commit 0bbca274a31c · 2016-03-11T10:23:28.000+02:00
After the GMBUS transfer times out, we set force_bit=1 and return -EAGAIN expecting the i2c core to call the .master_xfer hook again so that we will retry the same transfer via bit-banging. This is in case the gmbus hardware is somehow faulty. Unfortunately we left adapter->retries to 0, meaning the i2c core didn't actually do the retry. Let's tell the core we want one retry when we return -EAGAIN. Note that i2c-algo-bit also uses this retry count for some internal retries, so we'll end up increasing those a bit as well. Cc: Jani Nikula <jani.nikula@intel.com> Cc: drm-intel-fixes@lists.freedesktop.org Fixes: bffce90 ("drm/i915: abstract i2c bit banging fallback in gmbus xfer") Signed-off-by: Ville Syrjälä <ville.syrjala@linux.intel.com> Link: http://patchwork.freedesktop.org/patch/msgid/1457366220-29409-2-git-send-email-ville.syrjala@linux.intel.com Reviewed-by: Jani Nikula <jani.nikula@intel.com> (cherry picked from commit 8b1f165) Signed-off-by: Jani Nikula <jani.nikula@intel.com>
diff --git a/drivers/gpu/drm/i915/intel_i2c.c b/drivers/gpu/drm/i915/intel_i2c.c
@@ -664,6 +664,12 @@ int intel_setup_gmbus(struct drm_device *dev)
 
 		bus->adapter.algo = &gmbus_algorithm;
 
+		/*
+		 * We wish to retry with bit banging
+		 * after a timed out GMBUS attempt.
+		 */
+		bus->adapter.retries = 1;
+
 		/* By default use a conservative clock rate */
 		bus->reg0 = pin | GMBUS_RATE_100KHZ;
 
