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@xxxxxxxxxxxxxxx>
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@xxxxxxxxxxxxxxxxxxxxx/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.
