| Message ID | 20220825122241.273090-4-rf@opensource.cirrus.com (mailing list archive) |
|---|---|
| State | Superseded |
| Headers | show |
| Series | soundwire: Fixes for spurious and missing UNATTACH | expand |
Humm, I am struggling a bit more on this patch. On 8/25/22 14:22, Richard Fitzgerald wrote: > Rearrange sdw_handle_slave_status() so that any peripherals > on device #0 that are given a device ID are reported as > unattached. The ensures that UNATTACH status is not lost. > > Handle unenumerated devices first and update the > sdw_slave_status array to indicate IDs that must have become > UNATTACHED. > > Look for UNATTACHED devices after this so we can pick up > peripherals that were UNATTACHED in the original PING status > and those that were still ATTACHED at the time of the PING but > then reverted to unenumerated and were found by > sdw_program_device_num(). Are those two cases really lost completely? It's a bit surprising, I do recall that we added a recheck on the status, see the 'update_status' label in cdns_update_slave_status_work > As sdw_update_slave_status() is always processing a snapshot of > a PING from some time in the past, it is possible that the status > is changing while sdw_update_slave_status() is running. > > A peripheral could report attached in the PING, but detach and > revert to device #0 and then be found in the loop in > sdw_program_device_num(). Previously the code would not have > updated slave->status to UNATTACHED because there was never a > PING with that status. If the slave->status is not updated to > UNATTACHED the next PING will report it as ATTACHED, but its > slave->status is already ATTACHED so the re-attach will not be > properly handled. The idea of detecting first devices that become unattached - and later deal with device0 when they re-attach - was based on the fact that synchronization takes time. The absolute minimum is 16 frames per the SoundWire spec. I don't see how testing for the status[0] first in sdw_handle_slave_status() helps, the value is taken at the same time as status[1..11]. If you really want to take the last information, we should re-read the status from a new PING frame. > This situations happens fairly frequently with multiple > peripherals on a bus that are intentionally reset (for example > after downloading firmware). > > Signed-off-by: Richard Fitzgerald <rf@opensource.cirrus.com> > --- > drivers/soundwire/bus.c | 39 ++++++++++++++++++++++++++------------- > 1 file changed, 26 insertions(+), 13 deletions(-) > > diff --git a/drivers/soundwire/bus.c b/drivers/soundwire/bus.c > index bb8ce26c68b3..1212148ac251 100644 > --- a/drivers/soundwire/bus.c > +++ b/drivers/soundwire/bus.c > @@ -718,7 +718,8 @@ void sdw_extract_slave_id(struct sdw_bus *bus, > } > EXPORT_SYMBOL(sdw_extract_slave_id); > > -static int sdw_program_device_num(struct sdw_bus *bus) > +static int sdw_program_device_num(struct sdw_bus *bus, > + enum sdw_slave_status status[]) > { > u8 buf[SDW_NUM_DEV_ID_REGISTERS] = {0}; > struct sdw_slave *slave, *_s; > @@ -776,6 +777,12 @@ static int sdw_program_device_num(struct sdw_bus *bus) > return ret; > } > > + /* > + * It could have dropped off the bus since the > + * PING response so update the status array. > + */ > + status[slave->dev_num] = SDW_SLAVE_UNATTACHED; > + > break; > } > } > @@ -1735,10 +1742,21 @@ int sdw_handle_slave_status(struct sdw_bus *bus, > { > enum sdw_slave_status prev_status; > struct sdw_slave *slave; > + bool programmed_dev_num = false; > bool attached_initializing; > int i, ret = 0; > > - /* first check if any Slaves fell off the bus */ > + /* Handle any unenumerated peripherals */ > + if (status[0] == SDW_SLAVE_ATTACHED) { > + dev_dbg(bus->dev, "Slave attached, programming device number\n"); > + ret = sdw_program_device_num(bus, status); > + if (ret < 0) > + dev_warn(bus->dev, "Slave attach failed: %d\n", ret); > + > + programmed_dev_num = true; > + } > + > + /* Check if any fell off the bus */ > for (i = 1; i <= SDW_MAX_DEVICES; i++) { > mutex_lock(&bus->bus_lock); > if (test_bit(i, bus->assigned) == false) { > @@ -1764,17 +1782,12 @@ int sdw_handle_slave_status(struct sdw_bus *bus, > } > } > > - if (status[0] == SDW_SLAVE_ATTACHED) { > - dev_dbg(bus->dev, "Slave attached, programming device number\n"); > - ret = sdw_program_device_num(bus); > - if (ret < 0) > - dev_err(bus->dev, "Slave attach failed: %d\n", ret); > - /* > - * programming a device number will have side effects, > - * so we deal with other devices at a later time > - */ > - return ret; > - } > + /* > + * programming a device number will have side effects, > + * so we deal with other devices at a later time > + */ > + if (programmed_dev_num) > + return 0; > > /* Continue to check other slave statuses */ > for (i = 1; i <= SDW_MAX_DEVICES; i++) {
On 25/08/2022 15:24, Pierre-Louis Bossart wrote: > Humm, I am struggling a bit more on this patch. > > On 8/25/22 14:22, Richard Fitzgerald wrote: >> Rearrange sdw_handle_slave_status() so that any peripherals >> on device #0 that are given a device ID are reported as >> unattached. The ensures that UNATTACH status is not lost. >> >> Handle unenumerated devices first and update the >> sdw_slave_status array to indicate IDs that must have become >> UNATTACHED. >> >> Look for UNATTACHED devices after this so we can pick up >> peripherals that were UNATTACHED in the original PING status >> and those that were still ATTACHED at the time of the PING but >> then reverted to unenumerated and were found by >> sdw_program_device_num(). > > Are those two cases really lost completely? It's a bit surprising, I do > recall that we added a recheck on the status, see the 'update_status' > label in cdns_update_slave_status_work > Yes they are. We see this happen extremely frequently (like, almost every time) when we reset out peripherals after a firmware change. I saw that "try again" stuff in cdns_update_slave_status_work() but it's not fixing the problem. Maybe because it's looking for devices still on #0 but that isn't the problem. The cdns_update_slave_status_work() is running in one workqueue thread, child drivers in other threads. So for example: 1. Child driver #1 resets #1 2. PING: #1 has reverted to #0, #2 still ATTACHED 3. cdns_update_slave_status() snapshots the status. #2 is ATTACHED 4. #1 has gone so mark it UNATTACHED 5. Child driver #2 gets some CPU time and reset #2 5. PING: #2 has reset, both now on #0 but we are handling the previous PING 6. sdw_handle_slave_status() - snapshot PING (from step 3) says #2 is attached 7. Device on #0 so call sdw_program_device_num() 8. sdw_program_device_num() loops until no devices on #0, #1 and #2 are both reprogrammed, return from sdw_handle_slave_status() 10. PING: #1 and #2 both attached 11. cdns_update_slave_status() -> sdw_handle_slave_status() 12. #1 has changed UNATTACHED->ATTACHED, but we never got a PING with #2 unattached so its slave->status==ATTACHED, "it hasn't changed" (wrong!) Now, at step 10 the Cadence IP may have accumlated both UNATTACH and ATTACH flags, and perhaps it should be smarter about deciding what to report if there are multiple states. HOWEVER.... that's the behaviour of Cadence IP, other IP may be different so it's probably unwise to assume that the IP has "remembered" the UNATTACH state before it was reprogrammed. If we reprogrammed it, it was definitely UNATTACHED so let's say that. >> As sdw_update_slave_status() is always processing a snapshot of >> a PING from some time in the past, it is possible that the status >> is changing while sdw_update_slave_status() is running. >> >> A peripheral could report attached in the PING, but detach and >> revert to device #0 and then be found in the loop in >> sdw_program_device_num(). Previously the code would not have >> updated slave->status to UNATTACHED because there was never a >> PING with that status. If the slave->status is not updated to >> UNATTACHED the next PING will report it as ATTACHED, but its >> slave->status is already ATTACHED so the re-attach will not be >> properly handled. > The idea of detecting first devices that become unattached - and later > deal with device0 when they re-attach - was based on the fact that > synchronization takes time. The absolute minimum is 16 frames per the > SoundWire spec. > > I don't see how testing for the status[0] first in > sdw_handle_slave_status() helps, the value is taken at the same time as > status[1..11]. If you really want to take the last information, we > should re-read the status from a new PING frame. > > The point is to deal with unattached devices second, not first. If we do it first we might find some more that are unattached since the ping. Moving the unattach check second means we don't have to do it twice. >> This situations happens fairly frequently with multiple >> peripherals on a bus that are intentionally reset (for example >> after downloading firmware). >> >> Signed-off-by: Richard Fitzgerald <rf@opensource.cirrus.com> >> --- >> drivers/soundwire/bus.c | 39 ++++++++++++++++++++++++++------------- >> 1 file changed, 26 insertions(+), 13 deletions(-) >> >> diff --git a/drivers/soundwire/bus.c b/drivers/soundwire/bus.c >> index bb8ce26c68b3..1212148ac251 100644 >> --- a/drivers/soundwire/bus.c >> +++ b/drivers/soundwire/bus.c >> @@ -718,7 +718,8 @@ void sdw_extract_slave_id(struct sdw_bus *bus, >> } >> EXPORT_SYMBOL(sdw_extract_slave_id); >> >> -static int sdw_program_device_num(struct sdw_bus *bus) >> +static int sdw_program_device_num(struct sdw_bus *bus, >> + enum sdw_slave_status status[]) >> { >> u8 buf[SDW_NUM_DEV_ID_REGISTERS] = {0}; >> struct sdw_slave *slave, *_s; >> @@ -776,6 +777,12 @@ static int sdw_program_device_num(struct sdw_bus *bus) >> return ret; >> } >> >> + /* >> + * It could have dropped off the bus since the >> + * PING response so update the status array. >> + */ >> + status[slave->dev_num] = SDW_SLAVE_UNATTACHED; >> + >> break; >> } >> } >> @@ -1735,10 +1742,21 @@ int sdw_handle_slave_status(struct sdw_bus *bus, >> { >> enum sdw_slave_status prev_status; >> struct sdw_slave *slave; >> + bool programmed_dev_num = false; >> bool attached_initializing; >> int i, ret = 0; >> >> - /* first check if any Slaves fell off the bus */ >> + /* Handle any unenumerated peripherals */ >> + if (status[0] == SDW_SLAVE_ATTACHED) { >> + dev_dbg(bus->dev, "Slave attached, programming device number\n"); >> + ret = sdw_program_device_num(bus, status); >> + if (ret < 0) >> + dev_warn(bus->dev, "Slave attach failed: %d\n", ret); >> + >> + programmed_dev_num = true; >> + } >> + >> + /* Check if any fell off the bus */ >> for (i = 1; i <= SDW_MAX_DEVICES; i++) { >> mutex_lock(&bus->bus_lock); >> if (test_bit(i, bus->assigned) == false) { >> @@ -1764,17 +1782,12 @@ int sdw_handle_slave_status(struct sdw_bus *bus, >> } >> } >> >> - if (status[0] == SDW_SLAVE_ATTACHED) { >> - dev_dbg(bus->dev, "Slave attached, programming device number\n"); >> - ret = sdw_program_device_num(bus); >> - if (ret < 0) >> - dev_err(bus->dev, "Slave attach failed: %d\n", ret); >> - /* >> - * programming a device number will have side effects, >> - * so we deal with other devices at a later time >> - */ >> - return ret; >> - } >> + /* >> + * programming a device number will have side effects, >> + * so we deal with other devices at a later time >> + */ >> + if (programmed_dev_num) >> + return 0; >> >> /* Continue to check other slave statuses */ >> for (i = 1; i <= SDW_MAX_DEVICES; i++) {
>> On 8/25/22 14:22, Richard Fitzgerald wrote: >>> Rearrange sdw_handle_slave_status() so that any peripherals >>> on device #0 that are given a device ID are reported as >>> unattached. The ensures that UNATTACH status is not lost. >>> >>> Handle unenumerated devices first and update the >>> sdw_slave_status array to indicate IDs that must have become >>> UNATTACHED. >>> >>> Look for UNATTACHED devices after this so we can pick up >>> peripherals that were UNATTACHED in the original PING status >>> and those that were still ATTACHED at the time of the PING but >>> then reverted to unenumerated and were found by >>> sdw_program_device_num(). >> >> Are those two cases really lost completely? It's a bit surprising, I do >> recall that we added a recheck on the status, see the 'update_status' >> label in cdns_update_slave_status_work >> > > Yes they are. We see this happen extremely frequently (like, almost > every time) when we reset out peripherals after a firmware change. > > I saw that "try again" stuff in cdns_update_slave_status_work() but > it's not fixing the problem. Maybe because it's looking for devices > still on #0 but that isn't the problem. > > The cdns_update_slave_status_work() is running in one workqueue thread, > child drivers in other threads. So for example: > > 1. Child driver #1 resets #1 > 2. PING: #1 has reverted to #0, #2 still ATTACHED > 3. cdns_update_slave_status() snapshots the status. #2 is ATTACHED > 4. #1 has gone so mark it UNATTACHED > 5. Child driver #2 gets some CPU time and reset #2 > 5. PING: #2 has reset, both now on #0 but we are handling the previous > PING > 6. sdw_handle_slave_status() - snapshot PING (from step 3) says #2 is > attached > 7. Device on #0 so call sdw_program_device_num() > 8. sdw_program_device_num() loops until no devices on #0, #1 and #2 > are both reprogrammed, return from sdw_handle_slave_status() > 10. PING: #1 and #2 both attached > 11. cdns_update_slave_status() -> sdw_handle_slave_status() > 12. #1 has changed UNATTACHED->ATTACHED, but we never got a PING with > #2 unattached so its slave->status==ATTACHED, "it hasn't changed" > (wrong!) > > Now, at step 10 the Cadence IP may have accumlated both UNATTACH and > ATTACH flags, and perhaps it should be smarter about deciding what > to report if there are multiple states. HOWEVER.... that's the behaviour > of Cadence IP, other IP may be different so it's probably unwise to > assume that the IP has "remembered" the UNATTACH state before it was > reprogrammed. > > If we reprogrammed it, it was definitely UNATTACHED so let's say that. Thanks for the detailed answer, this sequence of events will certainly defeat the Cadence IP and the way sticky bits were handled. The UNATTACHED case was assumed to be a really rare case of losing sync, i.e. a SOFT_RESET in SoundWire parlance. If you explicitly do a device reset, that would be a new scenario that was not considered before on any of the existing SoundWire commercial devices. It's however something we need to support, and your work here is much appreciated. I still think we should re-check the actual status from a PING frame, in order to work with more current data than the sticky bits taken at an earlier time, but that would only be a minor improvement. I also have a vague feeling that additional work is needed to make sure the DAIs are not used before that second enumeration and all firmware download complete. I did a couple of tests last year where I used the debugfs interface to issue a device reset command while streaming audio, and the detach/reattach was not handled at the ASoC level. I really don't see any logical flaws in your patch as is, so Reviewed-by: Pierre-Louis Bossart <pierre-louis.bossart@linux.intel.com>
On 25/08/2022 16:25, Richard Fitzgerald wrote: > On 25/08/2022 15:24, Pierre-Louis Bossart wrote: >> Humm, I am struggling a bit more on this patch. >> >> On 8/25/22 14:22, Richard Fitzgerald wrote: >>> Rearrange sdw_handle_slave_status() so that any peripherals >>> on device #0 that are given a device ID are reported as >>> unattached. The ensures that UNATTACH status is not lost. >>> >>> Handle unenumerated devices first and update the >>> sdw_slave_status array to indicate IDs that must have become >>> UNATTACHED. >>> >>> Look for UNATTACHED devices after this so we can pick up >>> peripherals that were UNATTACHED in the original PING status >>> and those that were still ATTACHED at the time of the PING but >>> then reverted to unenumerated and were found by >>> sdw_program_device_num(). >> >> Are those two cases really lost completely? It's a bit surprising, I do >> recall that we added a recheck on the status, see the 'update_status' >> label in cdns_update_slave_status_work >> > > Yes they are. We see this happen extremely frequently (like, almost > every time) when we reset out peripherals after a firmware change. > > I saw that "try again" stuff in cdns_update_slave_status_work() but > it's not fixing the problem. Maybe because it's looking for devices > still on #0 but that isn't the problem. > > The cdns_update_slave_status_work() is running in one workqueue thread, > child drivers in other threads. So for example: > > 1. Child driver #1 resets #1 > 2. PING: #1 has reverted to #0, #2 still ATTACHED > 3. cdns_update_slave_status() snapshots the status. #2 is ATTACHED > 4. #1 has gone so mark it UNATTACHED > 5. Child driver #2 gets some CPU time and reset #2 > 5. PING: #2 has reset, both now on #0 but we are handling the previous > PING > 6. sdw_handle_slave_status() - snapshot PING (from step 3) says #2 is > attached > 7. Device on #0 so call sdw_program_device_num() > 8. sdw_program_device_num() loops until no devices on #0, #1 and #2 > are both reprogrammed, return from sdw_handle_slave_status() > 10. PING: #1 and #2 both attached > 11. cdns_update_slave_status() -> sdw_handle_slave_status() > 12. #1 has changed UNATTACHED->ATTACHED, but we never got a PING with > #2 unattached so its slave->status==ATTACHED, "it hasn't changed" > (wrong!) > > Now, at step 10 the Cadence IP may have accumlated both UNATTACH and > ATTACH flags, and perhaps it should be smarter about deciding what > to report if there are multiple states. HOWEVER.... that's the behaviour > of Cadence IP, other IP may be different so it's probably unwise to > assume that the IP has "remembered" the UNATTACH state before it was > reprogrammed. > After I wrote that I remembered why I rejected that solution. We don't know what order multiple events happened, so it's not valid to report a backlogged UNATTACH just becuse it's more "important". It's not necessarily accurate. I would worry about this: Real-world order: PING: UNATTACH See device on #0 and program new device ID PING: ATTACHED But because of the delay in handling PINGs the software sees: See device on #0 and program new device ID PING: UNATTACH PING: ATTACHED Giving a false UANATTACH. We know it's unattached if we found it on #0 so setting its state to UNATTACHED ensures our state is accurate. >> The idea of detecting first devices that become unattached - and later >> deal with device0 when they re-attach - was based on the fact that >> synchronization takes time. The absolute minimum is 16 frames per the >> SoundWire spec. >> My expectation was it was to ensure that the slave->dev was marked UNATTACHED before trying to re-enumerate it. Either way I think it's not taking into account that we don't know when the workqueue function will run or how long it will take. There's two chained workqueue functions to get to the point of handling a PING. So we can't be sure we'll handle a PING with the device unattaching before we see it on #0. >> I don't see how testing for the status[0] first in >> sdw_handle_slave_status() helps, the value is taken at the same time as >> status[1..11]. If you really want to take the last information, we >> should re-read the status from a new PING frame. >> >> > > The point is to deal with unattached devices second, not first. > If we do it first we might find some more that are unattached since > the ping. Moving the unattach check second means we don't have to > do it twice. > To clarify: the point was that if we check for unattaches first, when sdw_program_device_num() updates other slaves to UNATTACHED, we would then have to run the UNATTACHED loop again to deal with those. If we check for UNATTACHED second, it can pick up all new UNATTACHED in the one loop. There's no point checking for UNATTACH first since we can't rely on the old PING showing the unattach before we see that device on #0. There is another possible implementation that we only reprogram a device on #0 if the slave->state == UNATTACHED. I didn't really like that partly because we're leaving devices on #0 instead of enumerating them, but also because I worried that it might carry a risk of race conditions. But if you prefer that option I can try it.
On 26/08/2022 09:06, Pierre-Louis Bossart wrote: > <SNIP> > > Thanks for the detailed answer, this sequence of events will certainly > defeat the Cadence IP and the way sticky bits were handled. > > The UNATTACHED case was assumed to be a really rare case of losing sync, > i.e. a SOFT_RESET in SoundWire parlance. > > If you explicitly do a device reset, that would be a new scenario that > was not considered before on any of the existing SoundWire commercial > devices. It's however something we need to support, and your work here > is much appreciated. > > I still think we should re-check the actual status from a PING frame, in > order to work with more current data than the sticky bits taken at an > earlier time, but that would only be a minor improvement. > > I also have a vague feeling that additional work is needed to make sure > the DAIs are not used before that second enumeration and all firmware > download complete. I did a couple of tests last year where I used the > debugfs interface to issue a device reset command while streaming audio, > and the detach/reattach was not handled at the ASoC level. > > I really don't see any logical flaws in your patch as is, so > > Reviewed-by: Pierre-Louis Bossart <pierre-louis.bossart@linux.intel.com> > I have pushed an alternative fix that waits until it sees an UNATTACHED status before reprogramming the device ID. https://lore.kernel.org/lkml/20220829094458.1169504-1-rf@opensource.cirrus.com/T/#t I've tested it with 4 amps on the same bus, all being reset after their firmware has been downloaded. I leave it to you to choose which fix you prefer. The second fix is simpler and I didn't see any problems in testing.
On 25/08/2022 13:22, Richard Fitzgerald wrote: > Rearrange sdw_handle_slave_status() so that any peripherals > on device #0 that are given a device ID are reported as > unattached. The ensures that UNATTACH status is not lost. > > Handle unenumerated devices first and update the > sdw_slave_status array to indicate IDs that must have become > UNATTACHED. > Don't use this patch! I found there's a race condition with the Cadence interrupts. Use my alternative fix.
diff --git a/drivers/soundwire/bus.c b/drivers/soundwire/bus.c index bb8ce26c68b3..1212148ac251 100644 --- a/drivers/soundwire/bus.c +++ b/drivers/soundwire/bus.c @@ -718,7 +718,8 @@ void sdw_extract_slave_id(struct sdw_bus *bus, } EXPORT_SYMBOL(sdw_extract_slave_id); -static int sdw_program_device_num(struct sdw_bus *bus) +static int sdw_program_device_num(struct sdw_bus *bus, + enum sdw_slave_status status[]) { u8 buf[SDW_NUM_DEV_ID_REGISTERS] = {0}; struct sdw_slave *slave, *_s; @@ -776,6 +777,12 @@ static int sdw_program_device_num(struct sdw_bus *bus) return ret; } + /* + * It could have dropped off the bus since the + * PING response so update the status array. + */ + status[slave->dev_num] = SDW_SLAVE_UNATTACHED; + break; } } @@ -1735,10 +1742,21 @@ int sdw_handle_slave_status(struct sdw_bus *bus, { enum sdw_slave_status prev_status; struct sdw_slave *slave; + bool programmed_dev_num = false; bool attached_initializing; int i, ret = 0; - /* first check if any Slaves fell off the bus */ + /* Handle any unenumerated peripherals */ + if (status[0] == SDW_SLAVE_ATTACHED) { + dev_dbg(bus->dev, "Slave attached, programming device number\n"); + ret = sdw_program_device_num(bus, status); + if (ret < 0) + dev_warn(bus->dev, "Slave attach failed: %d\n", ret); + + programmed_dev_num = true; + } + + /* Check if any fell off the bus */ for (i = 1; i <= SDW_MAX_DEVICES; i++) { mutex_lock(&bus->bus_lock); if (test_bit(i, bus->assigned) == false) { @@ -1764,17 +1782,12 @@ int sdw_handle_slave_status(struct sdw_bus *bus, } } - if (status[0] == SDW_SLAVE_ATTACHED) { - dev_dbg(bus->dev, "Slave attached, programming device number\n"); - ret = sdw_program_device_num(bus); - if (ret < 0) - dev_err(bus->dev, "Slave attach failed: %d\n", ret); - /* - * programming a device number will have side effects, - * so we deal with other devices at a later time - */ - return ret; - } + /* + * programming a device number will have side effects, + * so we deal with other devices at a later time + */ + if (programmed_dev_num) + return 0; /* Continue to check other slave statuses */ for (i = 1; i <= SDW_MAX_DEVICES; i++) {
Rearrange sdw_handle_slave_status() so that any peripherals on device #0 that are given a device ID are reported as unattached. The ensures that UNATTACH status is not lost. Handle unenumerated devices first and update the sdw_slave_status array to indicate IDs that must have become UNATTACHED. Look for UNATTACHED devices after this so we can pick up peripherals that were UNATTACHED in the original PING status and those that were still ATTACHED at the time of the PING but then reverted to unenumerated and were found by sdw_program_device_num(). As sdw_update_slave_status() is always processing a snapshot of a PING from some time in the past, it is possible that the status is changing while sdw_update_slave_status() is running. A peripheral could report attached in the PING, but detach and revert to device #0 and then be found in the loop in sdw_program_device_num(). Previously the code would not have updated slave->status to UNATTACHED because there was never a PING with that status. If the slave->status is not updated to UNATTACHED the next PING will report it as ATTACHED, but its slave->status is already ATTACHED so the re-attach will not be properly handled. This situations happens fairly frequently with multiple peripherals on a bus that are intentionally reset (for example after downloading firmware). Signed-off-by: Richard Fitzgerald <rf@opensource.cirrus.com> --- drivers/soundwire/bus.c | 39 ++++++++++++++++++++++++++------------- 1 file changed, 26 insertions(+), 13 deletions(-)