[RFC PATCH 09/40] soundwire: cadence_master: fix usage of CONFIG_UPDATE

[Pierre-Louis Bossart]

Per the hardware documentation, all changes to MCP_CONFIG,
MCP_CONTROL, MCP_CMDCTRL and MCP_PHYCTRL need to be validated with a
self-clearing write to MCP_CONFIG_UPDATE.

For some reason, the existing code only does this write to
CONFIG_UPDATE when enabling interrupts. Add a helper and do the update
when the CONFIG is changed.

Signed-off-by: Pierre-Louis Bossart <pierre-louis.boss...@linux.intel.com>
---
 drivers/soundwire/cadence_master.c | 29 +++++++++++++++++++++--------
 1 file changed, 21 insertions(+), 8 deletions(-)

diff --git a/drivers/soundwire/cadence_master.c 
b/drivers/soundwire/cadence_master.c
index 9f611a1fff0a..eb46cf651d62 100644
--- a/drivers/soundwire/cadence_master.c
+++ b/drivers/soundwire/cadence_master.c
@@ -224,6 +224,22 @@ static int cdns_clear_bit(struct sdw_cdns *cdns, int 
offset, u32 value)
        return -EAGAIN;
 }
 
+/*
+ * all changes to the MCP_CONFIG, MCP_CONTROL, MCP_CMDCTRL and MCP_PHYCTRL
+ * need to be confirmed with a write to MCP_CONFIG_UPDATE
+ */
+static int cdns_update_config(struct sdw_cdns *cdns)
+{
+       int ret;
+
+       ret = cdns_clear_bit(cdns, CDNS_MCP_CONFIG_UPDATE,
+                            CDNS_MCP_CONFIG_UPDATE_BIT);
+       if (ret < 0)
+               dev_err(cdns->dev, "Config update timedout\n");
+
+       return ret;
+}
+
 /*
  * debugfs
  */
@@ -758,15 +774,9 @@ static int _cdns_enable_interrupt(struct sdw_cdns *cdns)
  */
 int sdw_cdns_enable_interrupt(struct sdw_cdns *cdns)
 {
-       int ret;
-
        _cdns_enable_interrupt(cdns);
-       ret = cdns_clear_bit(cdns, CDNS_MCP_CONFIG_UPDATE,
-                            CDNS_MCP_CONFIG_UPDATE_BIT);
-       if (ret < 0)
-               dev_err(cdns->dev, "Config update timedout\n");
 
-       return ret;
+       return 0;
 }
 EXPORT_SYMBOL(sdw_cdns_enable_interrupt);
 
@@ -943,7 +953,10 @@ int sdw_cdns_init(struct sdw_cdns *cdns)
 
        cdns_writel(cdns, CDNS_MCP_CONFIG, val);
 
-       return 0;
+       /* commit changes */
+       ret = cdns_update_config(cdns);
+
+       return ret;
 }
 EXPORT_SYMBOL(sdw_cdns_init);
 
-- 
2.20.1