soundwire: cadence: Drain the RX FIFO after an IO timeout

[ Upstream commit 2ef49b1598721ac3fb081d161bb4e7f1ea707b8e ]

If wait_for_completion_timeout() times-out in _cdns_xfer_msg() it
is possible that something could have been written to the RX FIFO.
In this case, we should drain the RX FIFO so that anything in it
doesn't carry over and mess up the next transfer.

Obviously, if we got to this state something went wrong, and we
don't really know the state of everything. The cleanup in this
situation cannot be bullet-proof but we should attempt to avoid
breaking future transaction, if only to reduce the amount of
error noise when debugging the failure from a kernel log.

Note that this patch only implements the draining for blocking
(non-deferred) transfers. The deferred API doesn't have any proper
handling of error conditions and would need some re-design before
implementing cleanup. That is a task for a separate patch...

Signed-off-by: Richard Fitzgerald <rf@opensource.cirrus.com>
Reviewed-by: Pierre-Louis Bossart <pierre-louis.bossart@linux.intel.com>
Link: https://lore.kernel.org/r/20221202161812.4186897-4-rf@opensource.cirrus.com
Signed-off-by: Vinod Koul <vkoul@kernel.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>

diff --git a/drivers/soundwire/cadence_master.c b/drivers/soundwire/cadence_master.c
index 6cd9db19758c9fe1e28133f6b3101f1346ac75dc..e7da7d7b213fb7bb1d5b5b50766a458385ab04d8 100644 (file)
--- a/drivers/soundwire/cadence_master.c
+++ b/drivers/soundwire/cadence_master.c
@@ -555,6 +555,29 @@ cdns_fill_msg_resp(struct sdw_cdns *cdns,
        return SDW_CMD_OK;
 }
 
+static void cdns_read_response(struct sdw_cdns *cdns)
+{
+       u32 num_resp, cmd_base;
+       int i;
+
+       /* RX_FIFO_AVAIL can be 2 entries more than the FIFO size */
+       BUILD_BUG_ON(ARRAY_SIZE(cdns->response_buf) < CDNS_MCP_CMD_LEN + 2);
+
+       num_resp = cdns_readl(cdns, CDNS_MCP_FIFOSTAT);
+       num_resp &= CDNS_MCP_RX_FIFO_AVAIL;
+       if (num_resp > ARRAY_SIZE(cdns->response_buf)) {
+               dev_warn(cdns->dev, "RX AVAIL %d too long\n", num_resp);
+               num_resp = ARRAY_SIZE(cdns->response_buf);
+       }
+
+       cmd_base = CDNS_MCP_CMD_BASE;
+
+       for (i = 0; i < num_resp; i++) {
+               cdns->response_buf[i] = cdns_readl(cdns, cmd_base);
+               cmd_base += CDNS_MCP_CMD_WORD_LEN;
+       }
+}
+
 static enum sdw_command_response
 _cdns_xfer_msg(struct sdw_cdns *cdns, struct sdw_msg *msg, int cmd,
               int offset, int count, bool defer)
@@ -596,6 +619,10 @@ _cdns_xfer_msg(struct sdw_cdns *cdns, struct sdw_msg *msg, int cmd,
                dev_err(cdns->dev, "IO transfer timed out, cmd %d device %d addr %x len %d\n",
                        cmd, msg->dev_num, msg->addr, msg->len);
                msg->len = 0;
+
+               /* Drain anything in the RX_FIFO */
+               cdns_read_response(cdns);
+
                return SDW_CMD_TIMEOUT;
        }
 
@@ -769,29 +796,6 @@ EXPORT_SYMBOL(cdns_read_ping_status);
  * IRQ handling
  */
 
-static void cdns_read_response(struct sdw_cdns *cdns)
-{
-       u32 num_resp, cmd_base;
-       int i;
-
-       /* RX_FIFO_AVAIL can be 2 entries more than the FIFO size */
-       BUILD_BUG_ON(ARRAY_SIZE(cdns->response_buf) < CDNS_MCP_CMD_LEN + 2);
-
-       num_resp = cdns_readl(cdns, CDNS_MCP_FIFOSTAT);
-       num_resp &= CDNS_MCP_RX_FIFO_AVAIL;
-       if (num_resp > ARRAY_SIZE(cdns->response_buf)) {
-               dev_warn(cdns->dev, "RX AVAIL %d too long\n", num_resp);
-               num_resp = ARRAY_SIZE(cdns->response_buf);
-       }
-
-       cmd_base = CDNS_MCP_CMD_BASE;
-
-       for (i = 0; i < num_resp; i++) {
-               cdns->response_buf[i] = cdns_readl(cdns, cmd_base);
-               cmd_base += CDNS_MCP_CMD_WORD_LEN;
-       }
-}
-
 static int cdns_update_slave_status(struct sdw_cdns *cdns,
                                    u64 slave_intstat)
 {