periods_max initialization in snd_usb_hardware

periods_max initialization in snd_usb_hardware

[Amit Nagal]

Hi ,

snd_usb_hardware is defined in sound/usb/pcm.c as :
static struct snd_pcm_hardware snd_usb_hardware =
{
                 .....
	.buffer_bytes_max =	1024 * 1024,
	.period_bytes_min =	64,
	.period_bytes_max =	512 * 1024,
	.periods_min =	2,
	.periods_max =	1024,
};

here periods_max is intialized with value = 1024 .

but going by buffer_bytes_max and period_bytes_min value defined above ,
periods_max = ( buffer_bytes_max / period_bytes_min ) = 16384 .

why this upper cap of  1024 is maintained for  periods_max even though from
calculation it comes as 16384 ?



Thanx & Regards
Amit Nagal

Re: periods_max initialization in snd_usb_hardware

[Clemens Ladisch]

Amit Nagal wrote:
> snd_usb_hardware is defined in sound/usb/pcm.c as ...
> periods_max is intialized with value = 1024 .
>
> but going by buffer_bytes_max and period_bytes_min value defined above ,
> periods_max = ( buffer_bytes_max / period_bytes_min ) = 16384 .
>
> why this upper cap of  1024 is maintained for  periods_max even though from
> calculation it comes as 16384 ?

The buffer is entirely handled by software; these limits are pretty much
arbitrary.

If there is a reason to change these limits, just send a patch.  :)


Regards,
Clemens