drm/i915/dp: retry i2c-over-aux seven times on AUX DEFER

Per DP1.2 spec.

Signed-off-by: Jani Nikula <jani.nikula@intel.com>
Reviewed-by: Todd Previte <tprevite@gmail.com>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>

diff --git a/drivers/gpu/drm/i915/intel_dp.c b/drivers/gpu/drm/i915/intel_dp.c
index 95a31598feda953055023dc8a1b8618ba77cbf67..5b02f9d069c32e2bd29a27a9baaec1d6fc05eb3e 100644 (file)
--- a/drivers/gpu/drm/i915/intel_dp.c
+++ b/drivers/gpu/drm/i915/intel_dp.c
@@ -654,7 +654,12 @@ intel_dp_i2c_aux_ch(struct i2c_adapter *adapter, int mode,
                break;
        }
 
-       for (retry = 0; retry < 5; retry++) {
+       /*
+        * DP1.2 sections 2.7.7.1.5.6.1 and 2.7.7.1.6.6.1: A DP Source device is
+        * required to retry at least seven times upon receiving AUX_DEFER
+        * before giving up the AUX transaction.
+        */
+       for (retry = 0; retry < 7; retry++) {
                ret = intel_dp_aux_ch(intel_dp,
                                      msg, msg_bytes,
                                      reply, reply_bytes);