On Thu, 09 Aug 2018 13:19:53 +0200, Chakravarthi Pradeep wrote: > > Hi Takashi, > > How to enable log from ALSA lib core or ALSA core , so that I will > come to know why trigger stop call back is getting called back by > itself. Do printk, tracing, whatever you can see. We have the standard tracepoints, too, but maybe it's not what you need. > ring bufffer size is 57600 and minimum bytes device generates per > period is 3200(bytes). I have read one frame is 4 bytes from below > link. > https://www.alsa-project.org/main/index.php/FramesPeriods > So is it correct to give below values to snd_pcm_hardware > .period_bytes_min = 3200 /* per interrupt device provides minimum 3200 > bytes of data*/ > .periods_min = 72 /* 3200/4 /* 4 is because of (2 (channel )* (16 bits/2)) */ period_bytes_min is 3200 bytes, so it looks correct. But periods_min is the minimal number of periods in a ring buffer. It can be calculated as (min buffer size) / (max period size). Takashi > > Regards, > Chakravarthi > On Tue, Aug 7, 2018 at 7:13 PM Takashi Iwai <tiwai@xxxxxxx> wrote: > > > > On Tue, 07 Aug 2018 15:36:22 +0200, > > Chakravarthi Pradeep wrote: > > > > > > >In the case above it's in frames. But it can be defined in bytes > > > >depending on the hardware spec. Some hardware defines in the time > > > >unit (like msec), too. > > > > > > Can you please tell me how to define in bytes ? > > > > Read the source before asking like this. If not found, read the > > source again. If still it's not fulfilled, ask more specific > > questions. > > > > The driver doesn't define it. Rather the driver lets ALSA PCM core > > choose the parameters given from user-space. But some parameters > > might not fit with the requirement of your hardware. For satisfying > > it, the driver may give hw constraints to PCM core beforehand, > > typically set in the open callback. > > > > > >Now you know it. And remember that PA is often die-hard. > > > So it means that I can not do rmmod until pulseaudio is removed , is > > > it correct ? > > > > Yes. You cannot rmmod during any program is accessing to the sound > > device, not only PA. > > > > > > Takashi > > > > > Regards, > > > Chakravarthi > > > On Tue, Aug 7, 2018 at 6:45 PM Takashi Iwai <tiwai@xxxxxxx> wrote: > > > > > > > > On Tue, 07 Aug 2018 15:12:08 +0200, > > > > Chakravarthi Pradeep wrote: > > > > > > > > > > Dear Takashi, > > > > > > > > > > Thanks for your reply. > > > > > > > > > > > The "period" in ALSA PCM definition represents the interval time (or > > > > > > frames) of the periodical interrupts on the ring buffer. If the irq > > > > > > is issued for each 256 frames while the ring buffer size is 1024 > > > > > > frames, periods = 1024/256 = 4. The periods_min defines the minimal > > > > > > number of periods the hardware may accept. > > > > > > > > > > Is it 256 frames or 256 bytes ? > > > > > > > > In the case above it's in frames. But it can be defined in bytes > > > > depending on the hardware spec. Some hardware defines in the time > > > > unit (like msec), too. > > > > > > > > > fuser -v /dev/snd/* output is > > > > > USER > > > > > PID ACCESS COMMAND > > > > > /dev/snd/controlC0 Dell 1815 > > > > > F..... pulseaudio > > > > > > > > Now you know it. And remember that PA is often die-hard. > > > > > > > > > > > > Takashi > > > > > > > > > > > > -- > > > Thanks and Regards > > > Chakravarthi Pradeep.K > > > Ph: 91 9980434900 > > > > > > > -- > Thanks and Regards > Chakravarthi Pradeep.K > Ph: 91 9980434900 > _______________________________________________ > Alsa-devel mailing list > Alsa-devel@xxxxxxxxxxxxxxxx > http://mailman.alsa-project.org/mailman/listinfo/alsa-devel > _______________________________________________ Alsa-devel mailing list Alsa-devel@xxxxxxxxxxxxxxxx http://mailman.alsa-project.org/mailman/listinfo/alsa-devel
