The existing code enables the Cadence IP interrupts after the bus
reset sequence. The problem with this sequence is that it might be
pre-empted, giving SoundWire devices time to sync and report as
ATTACHED before the interrupts are enabled. In that case, the Cadence
IP will not detect a state change and will not throw an interrupt to
proceed with the enumeration of a Device0.
In our overnight stress tests, we observed that a slight
sub-millisecond delay in enabling interrupts after the reset was
correlated with detection failures. This problem is more prevalent on
the LunarLake silicon, likely due to SOC integration changes, but it
was observed on earlier generations as well.
This patch reverts the sequence, with the interrupts enabled before
performing the bus reset. This removes the race condition and makes
sure the Cadence IP is able to detect the presence of a Device0 in all
cases.
Signed-off-by: Pierre-Louis Bossart <pierre-louis.bossart@linux.intel.com>
Signed-off-by: Bard Liao <yung-chuan.liao@linux.intel.com>
Link: https://lore.kernel.org/r/20240805115003.88035-1-yung-chuan.liao@linux.intel.com
Signed-off-by: Vinod Koul <vkoul@kernel.org>
The SoundWire peripheral enumeration is entirely based on interrupts,
more specifically sticky bits tracking state changes.
This patch adds a defensive programming check on the actual status
reported in PING frames. If for some reason an interrupt was lost or
delayed, the delayed work would detect a peripheral change of status
after the bus starts.
The 100ms defined for the delay is not completely arbitrary, if a
Peripheral didn't join the bus within that delay then probably the
hardware link is broken, and conversely if the detection didn't happen
because of software issues the 100ms is still acceptable in terms of
user experience.
The overhead of the one-shot workqueue is minimal, and the mutual
exclusion ensures that the interrupt and delayed work cannot update
the status concurrently.
Reviewed-by: Liam Girdwood <liam.r.girdwood@intel.com>
Signed-off-by: Pierre-Louis Bossart <pierre-louis.bossart@linux.intel.com>
Signed-off-by: Bard Liao <yung-chuan.liao@linux.intel.com>
Link: https://lore.kernel.org/r/20240805114921.88007-1-yung-chuan.liao@linux.intel.com
Signed-off-by: Vinod Koul <vkoul@kernel.org>
Now that the bus start/stop/clock_stop sequences use the ops, we can
move them to a different file to reuse them.
Note that we could in theory remove the abstraction for all those
sequences and directly call the functions in intel_auxdevice.c. To
allow for more flexibility and have means to special-case new
platforms, we decided to keep the abstraction. If in time it becomes
clear there is no benefit the abstraction will be simplified.
Signed-off-by: Pierre-Louis Bossart <pierre-louis.bossart@linux.intel.com>
Reviewed-by: Rander Wang <rander.wang@intel.com>
Signed-off-by: Bard Liao <yung-chuan.liao@linux.intel.com>
Link: https://lore.kernel.org/r/20230314015410.487311-9-yung-chuan.liao@linux.intel.com
Signed-off-by: Vinod Koul <vkoul@kernel.org>
