linux-kernel - [PATCH v4 1/5] soundwire: cadence: fix updating slave status when a bus has multiple peripherals

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Message-ID: <20220914160248.1047627-2-rf@opensource.cirrus.com>
Date:   Wed, 14 Sep 2022 17:02:44 +0100
From:   Richard Fitzgerald <rf@...nsource.cirrus.com>
To:     <vkoul@...nel.org>, <yung-chuan.liao@...ux.intel.com>,
        <pierre-louis.bossart@...ux.intel.com>, <sanyog.r.kale@...el.com>
CC:     <alsa-devel@...a-project.org>, <linux-kernel@...r.kernel.org>,
        <patches@...nsource.cirrus.com>,
        Simon Trimmer <simont@...nsource.cirrus.com>,
        Richard Fitzgerald <rf@...nsource.cirrus.com>
Subject: [PATCH v4 1/5] soundwire: cadence: fix updating slave status when a bus has multiple peripherals

From: Simon Trimmer <simont@...nsource.cirrus.com>

The cadence IP explicitly reports slave status changes with bits for
each possible change. The function cdns_update_slave_status() attempts
to translate this into the current status of each of the slaves.

However when there are multiple peripherals on a bus any slave that did
not have a status change when the work function ran would not have it's
status updated - the array is initialised to a value that equates to
UNATTACHED and this can cause spurious reports that slaves had dropped
off the bus.

In the case where a slave has no status change or has multiple status
changes the value from the last PING command is used.

Signed-off-by: Simon Trimmer <simont@...nsource.cirrus.com>
Signed-off-by: Richard Fitzgerald <rf@...nsource.cirrus.com>
Reviewed-by: Pierre-Louis Bossart <pierre-louis.bossart@...ux.intel.com>
---
 drivers/soundwire/cadence_master.c | 57 +++++++++++++-----------------
 1 file changed, 25 insertions(+), 32 deletions(-)

diff --git a/drivers/soundwire/cadence_master.c b/drivers/soundwire/cadence_master.c
index 4fbb19557f5e..245191d22ccd 100644
--- a/drivers/soundwire/cadence_master.c
+++ b/drivers/soundwire/cadence_master.c
@@ -782,6 +782,7 @@ static int cdns_update_slave_status(struct sdw_cdns *cdns,
 	enum sdw_slave_status status[SDW_MAX_DEVICES + 1];
 	bool is_slave = false;
 	u32 mask;
+	u32 val;
 	int i, set_status;
 
 	memset(status, 0, sizeof(status));
@@ -789,41 +790,38 @@ static int cdns_update_slave_status(struct sdw_cdns *cdns,
 	for (i = 0; i <= SDW_MAX_DEVICES; i++) {
 		mask = (slave_intstat >> (i * CDNS_MCP_SLAVE_STATUS_NUM)) &
 			CDNS_MCP_SLAVE_STATUS_BITS;
-		if (!mask)
-			continue;
 
-		is_slave = true;
 		set_status = 0;
 
-		if (mask & CDNS_MCP_SLAVE_INTSTAT_RESERVED) {
-			status[i] = SDW_SLAVE_RESERVED;
-			set_status++;
-		}
-
-		if (mask & CDNS_MCP_SLAVE_INTSTAT_ATTACHED) {
-			status[i] = SDW_SLAVE_ATTACHED;
-			set_status++;
-		}
+		if (mask) {
+			is_slave = true;
 
-		if (mask & CDNS_MCP_SLAVE_INTSTAT_ALERT) {
-			status[i] = SDW_SLAVE_ALERT;
-			set_status++;
-		}
+			if (mask & CDNS_MCP_SLAVE_INTSTAT_RESERVED) {
+				status[i] = SDW_SLAVE_RESERVED;
+				set_status++;
+			}
 
-		if (mask & CDNS_MCP_SLAVE_INTSTAT_NPRESENT) {
-			status[i] = SDW_SLAVE_UNATTACHED;
-			set_status++;
-		}
+			if (mask & CDNS_MCP_SLAVE_INTSTAT_ATTACHED) {
+				status[i] = SDW_SLAVE_ATTACHED;
+				set_status++;
+			}
 
-		/* first check if Slave reported multiple status */
-		if (set_status > 1) {
-			u32 val;
+			if (mask & CDNS_MCP_SLAVE_INTSTAT_ALERT) {
+				status[i] = SDW_SLAVE_ALERT;
+				set_status++;
+			}
 
-			dev_warn_ratelimited(cdns->dev,
-					     "Slave %d reported multiple Status: %d\n",
-					     i, mask);
+			if (mask & CDNS_MCP_SLAVE_INTSTAT_NPRESENT) {
+				status[i] = SDW_SLAVE_UNATTACHED;
+				set_status++;
+			}
+		}
 
-			/* check latest status extracted from PING commands */
+		/*
+		 * check that there was a single reported Slave status and when
+		 * there is not use the latest status extracted from PING commands
+		 */
+		if (set_status != 1) {
 			val = cdns_readl(cdns, CDNS_MCP_SLAVE_STAT);
 			val >>= (i * 2);
 
@@ -842,11 +840,6 @@ static int cdns_update_slave_status(struct sdw_cdns *cdns,
 				status[i] = SDW_SLAVE_RESERVED;
 				break;
 			}
-
-			dev_warn_ratelimited(cdns->dev,
-					     "Slave %d status updated to %d\n",
-					     i, status[i]);
-
 		}
 	}
 
-- 
2.30.2