print audio ring buffer in kernel space

print audio ring buffer in kernel space

[Ankhit Vivekananda]

Hello,

I am trying to print the ring buffer used for DMA transfer using ALSA in
kernel space. I was able to print the ring buffer in user space after
calling the snd_pcm_readi() function. But, wanted to know as to which file
I need to be looking at to print the hardware buffer in kernel space as I
am trying to debug capturing audio using ALSA.

I am using a MCBSP I2S on TM320DM365 processor and CQ93 on chip voice codec
driver.

Appreciate any help as I am new to ALSA.

Thank you.

Re: print audio ring buffer in kernel space

[Clemens Ladisch]

Ankhit Vivekananda wrote:
> I am trying to print the ring buffer used for DMA transfer using ALSA in
> kernel space. I was able to print the ring buffer in user space after
> calling the snd_pcm_readi() function. But, wanted to know as to which file
> I need to be looking at to print the hardware buffer in kernel space.

The driver typically does not access the buffer.  There is no such file.

(And why would you need it?  Do you suspect an error in the
implementation of snd_pcm_readi()?)


Regards,
Clemens

Re: print audio ring buffer in kernel space

[Ankhit Vivekananda]

No, I do not suspect an error in the snd_pcm_readi(), but would want to
print the data(using printk) from the hardware buffer directly, and see
that it matches with the buffer after snd_pcm_readi() call. I would want to
know where the hardware buffer is located at so that I can trace it down.

Regards,
Ankhit

On Thu, Oct 29, 2015 at 3:06 PM, Clemens Ladisch <clemens@ladisch.de> wrote:

> Ankhit Vivekananda wrote:
> > I am trying to print the ring buffer used for DMA transfer using ALSA in
> > kernel space. I was able to print the ring buffer in user space after
> > calling the snd_pcm_readi() function. But, wanted to know as to which
> file
> > I need to be looking at to print the hardware buffer in kernel space.
>
> The driver typically does not access the buffer.  There is no such file.
>
> (And why would you need it?  Do you suspect an error in the
> implementation of snd_pcm_readi()?)
>
>
> Regards,
> Clemens
>