[PATCH 1/3] soundwire: cadence: fix updating slave status when a bus has multiple peripherals

Richard Fitzgerald
2022-08-25T12:23:09Z

From: Simon Trimmer <simont@opensource.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@opensource.cirrus.com>
Signed-off-by: Richard Fitzgerald <rf@opensource.cirrus.com>
---
drivers/soundwire/cadence_master.c | 63 +++++++++++++-----------------
1 file changed, 28 insertions(+), 35 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) {
+ is_slave = true;
+
+ 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 & CDNS_MCP_SLAVE_INTSTAT_ALERT) {
+ status[i] = SDW_SLAVE_ALERT;
+ 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++;
- }
-
- if (mask & CDNS_MCP_SLAVE_INTSTAT_ALERT) {
- status[i] = SDW_SLAVE_ALERT;
- set_status++;
- }
-
- if (mask & CDNS_MCP_SLAVE_INTSTAT_NPRESENT) {
- status[i] = SDW_SLAVE_UNATTACHED;
- set_status++;
- }
-
- /* first check if Slave reported multiple status */
- if (set_status > 1) {
- u32 val;
-
- dev_warn_ratelimited(cdns->dev,
- "Slave %d reported multiple Status: %d\n",
- i, mask);
-
- /* 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