diff options
| author | Richard Fitzgerald | 2022-09-14 17:02:46 +0100 |
|---|---|---|
| committer | Vinod Koul | 2022-09-20 10:29:31 +0530 |
| commit | 7297f8fa9a4312701c5066cd0d22e1a252cbb2d7 (patch) | |
| tree | 67d2f71c84b4e834bf9b666d53570c0e5cce41fe /drivers | |
| parent | f605f32e59d8021a032746c2ca73b1adc46873d7 (diff) | |
soundwire: bus: Don't re-enumerate before status is UNATTACHED
Don't re-enumerate a peripheral on #0 until we have seen and
handled an UNATTACHED notification for that peripheral.
Without this, it is possible for the UNATTACHED status to be missed
and so the slave->status remains at ATTACHED. If slave->status never
changes to UNATTACHED the child driver will never be notified of the
UNATTACH, and the code in sdw_handle_slave_status() will skip the
second part of enumeration because the slave->status has not changed.
This scenario can happen because PINGs are handled in a workqueue
function which is working from a snapshot of an old PING, and there
is no guarantee when this function will run.
A peripheral could report attached in the PING being handled by
sdw_handle_slave_status(), but has since reverted to device #0 and is
then found in the loop in sdw_program_device_num(). Previously the
code would not have updated slave->status to UNATTACHED because it had
not yet handled a PING where that peripheral had UNATTACHED.
This situation 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>
Reviewed-by: Pierre-Louis Bossart <pierre-louis.bossart@linux.intel.com>
Link: https://lore.kernel.org/r/20220914160248.1047627-4-rf@opensource.cirrus.com
Signed-off-by: Vinod Koul <vkoul@kernel.org>
Diffstat (limited to 'drivers')
| -rw-r--r-- | drivers/soundwire/bus.c | 10 |
1 files changed, 10 insertions, 0 deletions
diff --git a/drivers/soundwire/bus.c b/drivers/soundwire/bus.c index 1cc858b4107d..6e569a875a9b 100644 --- a/drivers/soundwire/bus.c +++ b/drivers/soundwire/bus.c @@ -774,6 +774,16 @@ static int sdw_program_device_num(struct sdw_bus *bus) found = true; /* + * To prevent skipping state-machine stages don't + * program a device until we've seen it UNATTACH. + * Must return here because no other device on #0 + * can be detected until this one has been + * assigned a device ID. + */ + if (slave->status != SDW_SLAVE_UNATTACHED) + return 0; + + /* * Assign a new dev_num to this Slave and * not mark it present. It will be marked * present after it reports ATTACHED on new |