On Tue, 05 Sep 2017 10:58:37 +0200, Kuninori Morimoto wrote: > > Hi Takashi-san > > Thank you for your feedback > > > Right, you can't cancel or return an error at that point. > > That is, you'd need to sync (wait) until the all top-level operations are canceled at remove callback. > > > > For example, snd_card_free() processes the disconnection procedure at first, > > then waits for the completion. That's how the hot-unplug works safely. > > It's implemented, at least, in the top-level driver removal. > > > > Now for the lower level driver, you'd need a similar strategy; notify to the toplevel for > > hot-unplug (disconnect in ALSA), and sync with the stop operation, then continue the rest of its own remove procedure. > > OK, it needs ALSA SoC framework side new feature. Not only ASoC but also in all ALSA component generally. The component-level hot unplug isn't implemented yet properly. > But can I confirm current situation ? > > In ALSA SoC, it has Card/CPU/Codec/Platform drivers, and we can unbind these randomly. > Now, if I unbind CPU first, it checks connected Card, and will disconnect it if needed (Then, other drivers are as-is). > Because of this, Card will be disconnected automatically, and we can't use it again if user didn't remove all other > remaining drivers and re-bind all drivers again. This is current ALSA SoC I think. > > If my understanding was correct, your idea is that we want to call remove function for all connected drivers somehow. > And then, Card want to wait all drivers are removed. Correct ? Right. Unless we really want to support the hog-plug/unplug of each component, it'd be more straightforward to do the full hot-unplug upon every component unbind action. > I'm happy to work for it. > But adding new unplug feature is for sync with all "drivers", and this patch is sync for "clk" for my CPU driver. > Can we separate these ? It belongs with the same thing. Basically you're tweaking clk per PCM stream status. By handling the full hot-plug properly, the PCM stream is assured to be stopped, thus you don't have to fiddle with clk in the remove callback at all. Takashi _______________________________________________ Alsa-devel mailing list Alsa-devel@xxxxxxxxxxxxxxxx http://mailman.alsa-project.org/mailman/listinfo/alsa-devel
