drm/msm/dp: reset aux controller after dp_aux_cmd_fifo_tx() failed.

Aux hardware calibration sequence requires resetting the aux controller
in order for the new setting to take effect. However resetting the AUX
controller will also clear HPD interrupt status which may accidentally
cause pending unplug interrupt to get lost. Therefore reset aux
controller only when link is in connection state when dp_aux_cmd_fifo_tx()
fail. This fixes Link Layer CTS cases 4.2.1.1 and 4.2.1.2.

Signed-off-by: Kuogee Hsieh <[email protected]>
Reviewed-by: Stephen Boyd <[email protected]>
Link: https://lore.kernel.org/r/[email protected]
Signed-off-by: Rob Clark <[email protected]>

Author: Kuogee Hsieh

drivers/gpu/drm/msm/dp/dp_aux.c

@@ -353,6 +353,9 @@ static ssize_t dp_aux_transfer(struct drm_dp_aux *dp_aux,
 			if (!(aux->retry_cnt % MAX_AUX_RETRIES))
 				dp_catalog_aux_update_cfg(aux->catalog);
 		}
+		/* reset aux if link is in connected state */
+		if (dp_catalog_link_is_connected(aux->catalog))
+			dp_catalog_aux_reset(aux->catalog);
 	} else {
 		aux->retry_cnt = 0;
 		switch (aux->aux_error_num) {