On 23 June 2010 18:22, Adish Kuvelker <adkuvi@xxxxxxxxx> wrote: > Hello, > > I am developing a ALSA driver for the AtlasIII AC'97 Controller. The > AC'97 Controller FIFO is arranged as 16 32-bit entries. My PCM data > would be 16-bit samples and the driver will cater to 2-front channel > audio. I have configured the snd_pcm_hardware members as follows: > .formats = SNDDRV_PCM_FMTBIT_S16_LE > .period_bytes_max = 4, > .period_bytes_min = 64, > As I would need a minimum of 4-byte sample to be transferred and the > "period_bytes_max" value has been set considering the maximum size of > the FIFO in bytes. Is my understanding correct in doing these > settings? > > Secondly, I am having slight problems in understanding the > "snd_pcm_hardware" members periods_min and periods_max. Can anyone > throw some more light on this in addition to what is explained in the > "Writing an Audio Driver"? > max should = 64 min should = 4 periods_min and periods_max is dependent on when the sound card interrupts the CPU. So, if the CPU gets an interrupt once every 16 samples, then periods_min = periods_max = 1 If the sound card does not interrupt the CPU at all, you have to provide a method to notify the CPU when to next fill the FIFO. _______________________________________________ Alsa-devel mailing list Alsa-devel@xxxxxxxxxxxxxxxx http://mailman.alsa-project.org/mailman/listinfo/alsa-devel
