soundwire: cadence: fix a io timeout issue in S3 test

After system resumes from S3, io timeout occurs when setting one
unused master on Comet Lake platform. In this case, the master is
reset to default state, and FIFOLEVEL is reset to default value,
but msg_count used for tracing FIFOLEVEL is still with old value,
so FIFOLEVEL will not be set if a new msg FIFO usage is equal to
the old msg_count.

This patch updates msg_count to default value of FIFOLEVEL when
resetting master.

Tested on Comet Lake platform.

Signed-off-by: Rander Wang <rander.wang@intel.com>
Signed-off-by: Pierre-Louis Bossart <pierre-louis.bossart@linux.intel.com>
Link: https://lore.kernel.org/r/20200317163329.25501-7-pierre-louis.bossart@linux.intel.com
Signed-off-by: Vinod Koul <vkoul@kernel.org>

drivers/soundwire/cadence_master.c

@@ -1068,6 +1068,9 @@ int sdw_cdns_init(struct sdw_cdns *cdns)
 	cdns_writel(cdns, CDNS_MCP_SSP_CTRL0, CDNS_DEFAULT_SSP_INTERVAL);
 	cdns_writel(cdns, CDNS_MCP_SSP_CTRL1, CDNS_DEFAULT_SSP_INTERVAL);
 
+	/* reset msg_count to default value of FIFOLEVEL */
+	cdns->msg_count = cdns_readl(cdns, CDNS_MCP_FIFOLEVEL);
+
 	/* flush command FIFOs */
 	cdns_updatel(cdns, CDNS_MCP_CONTROL, CDNS_MCP_CONTROL_CMD_RST,
 		     CDNS_MCP_CONTROL_CMD_RST);