On Wed, Jul 05, 2023 at 02:53:17PM +0200, Pierre-Louis Bossart wrote: > On 7/5/23 14:30, Johan Hovold wrote: > > The soundwire subsystem uses two completion structures that allow > > drivers to wait for soundwire device to become enumerated on the bus and > > initialised by their drivers, respectively. > > > > The code implementing the signalling is currently broken as it does not > > signal all current and future waiters and also uses the wrong > > reinitialisation function, which can potentially lead to memory > > corruption if there are still waiters on the queue. > > That change sounds good, but I am not following the two paragraphs below. > > > Not signalling future waiters specifically breaks sound card probe > > deferrals as codec drivers can not tell that the soundwire device is > > already attached when being reprobed. > > What makes you say that? There is a test in the probe and the codec > driver will absolutely be notified, see bus_type.c > > if (drv->ops && drv->ops->update_status) { > ret = drv->ops->update_status(slave, slave->status); > if (ret < 0) > dev_warn(dev, "%s: update_status failed with status %d\n", __func__, > ret); > } I'm talking about signalling the codec driver using the soundwire device via the completion structs. Unless the underling device is detached and reattached, trying to wait for completion a second time will currently timeout instead of returning immediately. This affects codecs like rt5682, which wait for completion in component probe (see rt5682_probe()). > > Some codec runtime PM > > implementations suffer from similar problems as waiting for enumeration > > during resume can also timeout despite the device already having been > > enumerated. > > I am not following this either. Are you saying the wait_for_completion() > times out because of the init_completion/reinit_completion confusion, or > something else. It times out because the completion counter is not saturated unless you use complete_all(). Drivers that wait unconditionally in resume, will time out the second time they are runtime resumed unless the underlying device has been detached and reattached in the meantime (e.g. wsa881x_runtime_resume()). Johan