[PATCH 5.4 204/340] soundwire: cadence: fix ACK/NAK handling

[Greg Kroah-Hartman]

From: Pierre-Louis Bossart <pierre-louis.bossart@xxxxxxxxxxxxxxx>

[ Upstream commit db9d9f944f95e7f3aa60ac00cbd502415152c421 ]

The existing code reports a NAK only when ACK=0
This is not aligned with the SoundWire 1.x specifications.

Table 32 in the SoundWire 1.2 specification shows that a Device shall
not set NAK=1 if ACK=1. But Table 33 shows the Combined Response
may very well be NAK=1/ACK=1, e.g. if another Device than the one
addressed reports a parity error.

NAK=1 signals a 'Command_Aborted', regardless of the ACK bit value.

Move the tests for NAK so that the NAK=1/ACK=1 combination is properly
detected according to the specification.

Fixes: 956baa1992f9a ('soundwire: cdns: Add sdw_master_ops and IO transfer support')
Signed-off-by: Pierre-Louis Bossart <pierre-louis.bossart@xxxxxxxxxxxxxxx>
Signed-off-by: Bard Liao <yung-chuan.liao@xxxxxxxxxxxxxxx>
Link: https://lore.kernel.org/r/20210115053738.22630-5-yung-chuan.liao@xxxxxxxxxxxxxxx
Signed-off-by: Vinod Koul <vkoul@xxxxxxxxxx>
Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>
---
 drivers/soundwire/cadence_master.c | 8 ++++----
 1 file changed, 4 insertions(+), 4 deletions(-)

diff --git a/drivers/soundwire/cadence_master.c b/drivers/soundwire/cadence_master.c
index e3d06330d1258..f7d0f63921dc2 100644
--- a/drivers/soundwire/cadence_master.c
+++ b/drivers/soundwire/cadence_master.c
@@ -368,10 +368,10 @@ cdns_fill_msg_resp(struct sdw_cdns *cdns,
 		if (!(cdns->response_buf[i] & CDNS_MCP_RESP_ACK)) {
 			no_ack = 1;
 			dev_dbg_ratelimited(cdns->dev, "Msg Ack not received\n");
-			if (cdns->response_buf[i] & CDNS_MCP_RESP_NACK) {
-				nack = 1;
-				dev_err_ratelimited(cdns->dev, "Msg NACK received\n");
-			}
+		}
+		if (cdns->response_buf[i] & CDNS_MCP_RESP_NACK) {
+			nack = 1;
+			dev_err_ratelimited(cdns->dev, "Msg NACK received\n");
 		}
 	}
 
-- 
2.27.0