soundwire: intel/cadence: update hardware reset sequence

Combining hardware reset with the multi-link mode leads to a shortened
hardware reset pattern observed on the bus.

The updated hardware programming sequence is to first enable the clock
with the sync_arm/sync_go pattern, and only in a second step to issue
the hardware reset sequence. Since there is no longer a dependency
between sync_arm/sync_go and hw_reset, the behavior of
sdw_cdns_exit_reset() is changed to wait for the self-clearing
CONFIG_UPDATE to go back to zero,

Link: https://github.com/thesofproject/linux/issues/4170
Signed-off-by: Pierre-Louis Bossart <pierre-louis.bossart@linux.intel.com>
Reviewed-by: Rander Wang <rander.wang@intel.com>
Signed-off-by: Bard Liao <yung-chuan.liao@linux.intel.com>
Link: https://lore.kernel.org/r/20230518024119.164160-3-yung-chuan.liao@linux.intel.com
Signed-off-by: Vinod Koul <vkoul@kernel.org>

1 files changed, 24 insertions, 7 deletions

diff --git a/drivers/soundwire/cadence_master.c b/drivers/soundwire/cadence_master.c
index 39502bc75712..58686ae50bbf 100644
--- a/drivers/soundwire/cadence_master.c
+++ b/drivers/soundwire/cadence_master.c
@@ -283,6 +283,29 @@ static int cdns_config_update(struct sdw_cdns *cdns)
 	return ret;
 }
 
+/**
+ * sdw_cdns_config_update() - Update configurations
+ * @cdns: Cadence instance
+ */
+void sdw_cdns_config_update(struct sdw_cdns *cdns)
+{
+	/* commit changes */
+	cdns_writel(cdns, CDNS_MCP_CONFIG_UPDATE, CDNS_MCP_CONFIG_UPDATE_BIT);
+}
+EXPORT_SYMBOL(sdw_cdns_config_update);
+
+/**
+ * sdw_cdns_config_update_set_wait() - wait until configuration update bit is self-cleared
+ * @cdns: Cadence instance
+ */
+int sdw_cdns_config_update_set_wait(struct sdw_cdns *cdns)
+{
+	/* the hardware recommendation is to wait at least 300us */
+	return cdns_set_wait(cdns, CDNS_MCP_CONFIG_UPDATE,
+			     CDNS_MCP_CONFIG_UPDATE_BIT, 0);
+}
+EXPORT_SYMBOL(sdw_cdns_config_update_set_wait);
+
 /*
  * debugfs
  */
@@ -1116,13 +1139,7 @@ int sdw_cdns_exit_reset(struct sdw_cdns *cdns)
 		     CDNS_MCP_CONTROL_HW_RST);
 
 	/* commit changes */
-	cdns_updatel(cdns, CDNS_MCP_CONFIG_UPDATE,
-		     CDNS_MCP_CONFIG_UPDATE_BIT,
-		     CDNS_MCP_CONFIG_UPDATE_BIT);
-
-	/* don't wait here */
-	return 0;
-
+	return cdns_config_update(cdns);
 }
 EXPORT_SYMBOL(sdw_cdns_exit_reset);