diff options
Diffstat (limited to 'drivers/soundwire/cadence_master.c')
| -rw-r--r-- | drivers/soundwire/cadence_master.c | 37 |
1 files changed, 37 insertions, 0 deletions
diff --git a/drivers/soundwire/cadence_master.c b/drivers/soundwire/cadence_master.c index 558390af44b6..47d59190a96e 100644 --- a/drivers/soundwire/cadence_master.c +++ b/drivers/soundwire/cadence_master.c @@ -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); @@ -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. + * + * 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, |