[alsa-devel] [PATCH v3 0/3] introduce device_buffer

Vinod Koul vinod.koul at linux.intel.com
Fri Aug 31 16:53:18 CEST 2012

On Fri, 2012-08-31 at 12:41 +0200, Jaroslav Kysela wrote:
> Date 31.8.2012 03:14, Vinod Koul wrote:
> > Old wine in a new bottle with added flavour now.
> > Based on our discussions in LPC, now we will report the combined delay value as
> > sum of the buffering done in driver and hardware. This is used to report delay
> > Additionally we tell pcm what is buffer in device/driver, this is used to check
> > for error calulcations
> I'm afraid, but this won't work for the mmaped appl_ptr / hw_ptr,
> because the checks are done outside the kernel - in alsa-lib. I believe
> that this API should be enhanced, too. But the question is, how to pass
> two values (hwptr, device_buffer) atomically to the user space without
> locks for x86.
Yes for mmap case, tis needs to be done in lib and that can't be done
without ABI/API changes??
Is there a reserved field we can perhaps use for this


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