[alsa-devel] Alsa-lib Dmix issue

[Anoop Rajan]

Hello Clemens,

>When there are multiple clients, there are multiple appl pointers.
>So the dmix plugin does not bother to tell the hardware about any
>of them.
Thanks,Understood.


>Are you using a driver that lokos at appl_ptr?
We are working on Marvell chipset,88DE3006. Looks like our driver looks at
appl_pointer though I am not sure how to confirm it. I see the appl_pointer
coming through SNDRV_PCM_IOCTL_SYNC_PTR is always incremented in case of
aplay -M and it works, if we don't increment appl_ptr it doesn't works,

So for dmix to work, I should have the driver that doesn't looks at
appl_ptr, right? f appl_pointer should never be incremented, how will the
kernel know the data is written? The MMAP to status/control is not
implemented in our case.  I would start looking to change my driver not to
look at appl_ptr, would you please help me with some pointers to understand
how/where in drivers should I typically change to adapt these changes?

Regards,
Anoop




On Thu, Jan 26, 2017 at 5:33 PM, Clemens Ladisch <clemens at ladisch.de> wrote:

> Anoop Rajan wrote:
> > I assume the issue is in Dmix, it is not incrementing the appl pointer.
>
> When there are multiple clients, there are multiple appl pointers.
> So the dmix plugin does not bother to tell the hardware about any
> of them.
>
> Are you using a driver that lokos at appl_ptr?
>
>
> Regards,
> Clemens
>