[top posting] I reverted this patch in the SOF tree to use Richard Fitzgerald's series, see https://github.com/thesofproject/linux/pull/3836 I don't think we want this patch upstream, do we? On 8/30/22 09:42, Bard Liao wrote: > From: Pierre-Louis Bossart <pierre-louis.bossart@xxxxxxxxxxxxxxx> > > In configurations with two amplifiers on the same link, the Intel CI > reports occasional enumeration/initialization timeouts during > suspend-resume stress tests, where one of the two amplifiers becomes > UNATTACHED immediately after being enumerated. This problem was > reported both with Maxim and Realtek codecs, which pointed initially > to a problem with status handling on the Intel side. > > The Cadence IP integrated on Intel platforms throws an interrupt when > the status changes, and the information is kept with sticky bits until > cleared. We initially added more checks to make sure the edge > detection did not miss any transition, but that did not improve the > results significantly. > > With the recent addition of the read_ping_status() callback, we were > able to show that the status in sticky bits is shown as UNATTACHED > even though the PING frames show the problematic device as > ATTACHED. That completely breaks the entire logic where we assumed > that a peripheral would always re-attach as device0. The resume > timeouts make sense in that in those cases, the > enumeration/initialization never happens a second time. > > One possible explanation is that this problem typically happens when a > bus clash is reported, so it could very well be that the detection is > fooled by a transient electrical issue or conflict between two > peripherals. > > This patch conditionally double-checks the status reported in the > sticky bits with the actual PING frame status. If the peripheral > reports as attached in PING frames, the early detection based on > sticky bits is discarded. > > Note that this patch only corrects issues of false positives on the > manager side. > > If the peripheral lost and regain sync, then it would report as > attached on Device0. A peripheral that would not reset its dev_num > would not be compliant with the MIPI specification. > > BugLink: https://github.com/thesofproject/linux/issues/3638 > BugLink: https://github.com/thesofproject/linux/issues/3325 > Signed-off-by: Pierre-Louis Bossart <pierre-louis.bossart@xxxxxxxxxxxxxxx> > Reviewed-by: Rander Wang <rander.wang@xxxxxxxxx> > Signed-off-by: Bard Liao <yung-chuan.liao@xxxxxxxxxxxxxxx> > --- > Hi Vinod, > > You will need the "ASoC/soundwire: log actual PING status on resume issues" > series which is applied at ASoC tree before appling this patch. > > --- > drivers/soundwire/bus.c | 19 +++++++++++++++++++ > drivers/soundwire/intel.c | 1 + > include/linux/soundwire/sdw.h | 3 +++ > 3 files changed, 23 insertions(+) > > diff --git a/drivers/soundwire/bus.c b/drivers/soundwire/bus.c > index 2772973eebb1..d0d486f07673 100644 > --- a/drivers/soundwire/bus.c > +++ b/drivers/soundwire/bus.c > @@ -1767,6 +1767,25 @@ int sdw_handle_slave_status(struct sdw_bus *bus, > slave->status != SDW_SLAVE_UNATTACHED) { > dev_warn(&slave->dev, "Slave %d state check1: UNATTACHED, status was %d\n", > i, slave->status); > + > + if (bus->recheck_unattached && bus->ops->read_ping_status) { > + u32 ping_status; > + > + mutex_lock(&bus->msg_lock); > + > + ping_status = bus->ops->read_ping_status(bus); > + > + mutex_unlock(&bus->msg_lock); > + > + ping_status >>= (i * 2); > + ping_status &= 0x3; > + > + if (ping_status != 0) { > + dev_warn(&slave->dev, "Slave %d state in PING frame is %d, ignoring earlier detection\n", > + i, ping_status); > + continue; > + } > + } > sdw_modify_slave_status(slave, SDW_SLAVE_UNATTACHED); > } > } > diff --git a/drivers/soundwire/intel.c b/drivers/soundwire/intel.c > index 25ec9c272239..0c6e674dbf85 100644 > --- a/drivers/soundwire/intel.c > +++ b/drivers/soundwire/intel.c > @@ -1311,6 +1311,7 @@ static int intel_link_probe(struct auxiliary_device *auxdev, > > bus->link_id = auxdev->id; > bus->dev_num_ida_min = INTEL_DEV_NUM_IDA_MIN; > + bus->recheck_unattached = true; > > sdw_cdns_probe(cdns); > > diff --git a/include/linux/soundwire/sdw.h b/include/linux/soundwire/sdw.h > index a2b31d25ea27..51ac71984260 100644 > --- a/include/linux/soundwire/sdw.h > +++ b/include/linux/soundwire/sdw.h > @@ -892,6 +892,8 @@ struct sdw_master_ops { > * @dev_num_ida_min: if set, defines the minimum values for the IDA > * used to allocate system-unique device numbers. This value needs to be > * identical across all SoundWire bus in the system. > + * @recheck_unattached: if set, double-check UNATTACHED status changes > + * by reading PING frame status. > */ > struct sdw_bus { > struct device *dev; > @@ -917,6 +919,7 @@ struct sdw_bus { > bool multi_link; > int hw_sync_min_links; > int dev_num_ida_min; > + bool recheck_unattached; > }; > > int sdw_bus_master_add(struct sdw_bus *bus, struct device *parent,
