Re: [PATCH 0/2] soundwire: suppress expected unattach warnings during codec reset

[Richard Fitzgerald]

On 17/2/26 23:35, Cole Leavitt wrote:
> On systems with CS35L56 SoundWire codecs (e.g. Lenovo ThinkPad P16
> Gen3), every boot produces misleading dev_warn() messages:
>
>    cs35l56 sdw:0:2:01fa:3556:01:0: Slave 2 state check1: UNATTACHED, status was 1
>    cs35l56 sdw:0:2:01fa:3556:01:1: Slave 1 state check1: UNATTACHED, status was 1

Is this really a problem?
They are warns, not errors. Nothing in that message says that this is
an error, or that it's unexpected. The message is accurate.

> These fire when the CS35L56 driver triggers a system reset after
> firmware download, which physically detaches the codec from the bus.
> This is expected and handled gracefully -- the driver waits for
> re-enumeration and the codec recovers within milliseconds.
>
> The warnings were added in commit d1b328557058 ("soundwire: bus: add
> dev_warn() messages to track UNATTACHED devices") to debug genuine
> attachment failures. They remain valuable for unexpected detachments,
> but firing on every boot for normal codec operation degrades their
> diagnostic value.
>
> This series adds a simple boolean flag (unattach_pending) to struct
> sdw_slave that codec drivers can set before triggering an expected
> detach. When set, the bus layer emits dev_dbg() instead of dev_warn()
> and auto-clears the flag.
>
> Note: There is also a separate set of UNATTACHED warnings during
> initial multi-device enumeration, caused by the known PING frame race
> documented in cadence_master.c. That is a different problem with
> different constraints and is not addressed here.
>
> Cole Leavitt (2):
>    soundwire: bus: downgrade expected unattach warnings to dev_dbg
>    ASoC: cs35l56: set unattach_pending before SoundWire system reset
>
>   drivers/soundwire/bus.c       | 9 +++++++--
>   include/linux/soundwire/sdw.h | 1 +
>   sound/soc/codecs/cs35l56.c    | 4 ++++
>   3 files changed, 12 insertions(+), 2 deletions(-)