On 8/25/22 14:22, Richard Fitzgerald wrote: > From: Simon Trimmer <simont@xxxxxxxxxxxxxxxxxxxxx> > > 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@xxxxxxxxxxxxxxxxxxxxx> > Signed-off-by: Richard Fitzgerald <rf@xxxxxxxxxxxxxxxxxxxxx> Goodness, this is one bug fix. We've been chasing such issues for a while with 2 amps on the same link https://github.com/thesofproject/linux/issues/3638 https://github.com/thesofproject/linux/issues/3325 and also came up with the same conclusion that there were false reports of UNATTACHED, and the conclusion was also to use the PING status directly. see https://github.com/thesofproject/linux/pull/3786 I think this patch is much better than what I suggested, in that it fixes the root cause for the false report instead of double-checking if a device is truly UNATTACHED. Nice work! Reviewed-by: Pierre-Louis Bossart <pierre-louis.bossart@xxxxxxxxxxxxxxx> > --- > 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]); > - > } > } >
