On Fri, 19 Feb 2016 17:04:14 +0100, Takashi Iwai wrote: > > On Fri, 19 Feb 2016 16:51:55 +0100, > Takashi Sakamoto wrote: > > > > On Feb 19 2016 18:46, Takashi Iwai wrote: > > > On Fri, 19 Feb 2016 10:23:36 +0100, > > > Takashi Sakamoto wrote: > > >> > > >> Hi, > > >> > > >> On Feb 19 2016 17:19, Takashi Iwai wrote: > > >>> On Fri, 19 Feb 2016 01:55:50 +0100, > > >>> Takashi Sakamoto wrote: > > >>>> > > >>>> With a previous commit, ALSA oxfw driver retries transferring MIDI > > >>>> messages at transaction failure for scs1x. On the other hand, there're > > >>>> fatal transaction error. Then, MIDI messages never reach to the unit > > >>>> anymore. In this case, MIDI substream should be discontinued. > > >>>> > > >>>> This commit stops MIDI transferring after the fatal error occurs. > > >>>> Unfortunately, unlike ALSA PCM functionality, ALSA rawmidi core has no > > >>>> feature to discontinue MIDI substream in kernel side, thus this commit > > >>>> just stops MIDI transferring without notifying it to userspace. > > >>> > > >>> It's fine to take this, and I would take it as is for now. > > >> > > >> OK. > > >> > > >>> But we can extend the rawmidi somehow to deal with such an error, too. > > >>> Maybe just having "error" flag in the rawmidi runtime and adding a > > >>> helper function to set the error and stop the stream should work > > >>> easily. > > >> > > >> You forgot ALSA sequencer. > > > > > > This is a different layer. The sequencer stuff may check the error > > > and handle more gracefully than as of now, but it's a different story > > > from the extension of rawmidi itself. > > > > > > What you're working on is the rawmidi, and what it can give is just > > > returning an error at the right moment. > > > > I don't think so. I think the work is heavier than your expectation. > > > > I pushed 'rawmidi-epipe' branch to my repository. > > https://github.com/takaswie/sound/tree/rawmidi-epipe > > > > You can see four commits just to show my concerns. > > (They're not tested yet. Don't use them for actual work ;) > > 41f499b ALSA: rawmidi: add a helper to set runtime error > > 4164edb ALSA: rawmidi: handle EPIPE > > 5e7348ed ALSA: seq: handle EPIPE for rawmidi input > > 58d9008 ALSA: seq: handle EPIPE for rawmidi output > > > > In the top-most commit, you can see userspace applications need to > > close/open character devices to recover from EPIPE state of rawmidi > > substream runtime. > > Yes, this doesn't change from the current situation. > > Remember that rawmidi may return an error already in the current > implementation. The new feature would be just to add the explicit > trigger of the error, instead of implicit runtime->avail check. BTW, you'd need to put more error checks. There are other loops in snd_rawmidi_read() and snd_rawmidi_write() before snd_rawmidi_kernel_read1() and snd_rawmidi_kernel_write1() is reached. The check is needed there, too. Takashi _______________________________________________ Alsa-devel mailing list Alsa-devel@xxxxxxxxxxxxxxxx http://mailman.alsa-project.org/mailman/listinfo/alsa-devel
