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soundwire: cadence: recheck device0 attachment after status change #3442

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Merged
plbossart merged 1 commit into from
Feb 24, 2022
Merged

soundwire: cadence: recheck device0 attachment after status change #3442

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37 changes: 37 additions & 0 deletions drivers/soundwire/cadence_master.c
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Original file line number Diff line number Diff line change
Expand Up @@ -959,6 +959,8 @@ static void cdns_update_slave_status_work(struct work_struct *work)
container_of(work, struct sdw_cdns, work);
u32 slave0, slave1;
u64 slave_intstat;
u32 device0_status;
int retry_count = 0;

slave0 = cdns_readl(cdns, CDNS_MCP_SLAVE_INTSTAT0);
slave1 = cdns_readl(cdns, CDNS_MCP_SLAVE_INTSTAT1);
Expand All @@ -968,10 +970,45 @@ static void cdns_update_slave_status_work(struct work_struct *work)

dev_dbg_ratelimited(cdns->dev, "Slave status change: 0x%llx\n", slave_intstat);

update_status:
cdns_update_slave_status(cdns, slave_intstat);
cdns_writel(cdns, CDNS_MCP_SLAVE_INTSTAT0, slave0);
cdns_writel(cdns, CDNS_MCP_SLAVE_INTSTAT1, slave1);

/*
* When there is more than one peripheral per link, it's
* possible that a deviceB becomes attached after we deal with
* the attachment of deviceA. Since the hardware does a
* logical AND, the attachment of the second device does not
* change the status seen by the driver.
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RanderWang marked this conversation as resolved.
*
* In that case, clearing the registers above would result in
* the deviceB never being detected - until a change of status
* is observed on the bus.
*
* To avoid this race condition, re-check if any device0 needs
* attention with PING commands. There is no need to check for
* ALERTS since they are not allowed until a non-zero
* device_number is assigned.
*/

device0_status = cdns_readl(cdns, CDNS_MCP_SLAVE_STAT);
device0_status &= 3;

if (device0_status == SDW_SLAVE_ATTACHED) {
if (retry_count++ < SDW_MAX_DEVICES) {
dev_dbg_ratelimited(cdns->dev,
"Device0 detected after clearing status, iteration %d\n",
retry_count);
slave_intstat = CDNS_MCP_SLAVE_INTSTAT_ATTACHED;
goto update_status;
} else {
dev_err_ratelimited(cdns->dev,
"Device0 detected after %d iterations\n",
retry_count);
}
}

/* clear and unmask Slave interrupt now */
cdns_writel(cdns, CDNS_MCP_INTSTAT, CDNS_MCP_INT_SLAVE_MASK);
cdns_updatel(cdns, CDNS_MCP_INTMASK,
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