From mboxrd@z Thu Jan  1 00:00:00 1970
From: Clemens Ladisch <clemens@ladisch.de>
Subject: Re: how to update hw_ptr and appl_ptr
Date: Tue, 26 Jun 2012 14:27:04 +0200
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To: Zhen Fu <fuzh@marvell.com>
Cc: alsa-devel@alsa-project.org
List-Id: alsa-devel@alsa-project.org

Zhen Fu wrote:
> when DMA handler called snd_pcm_period_elapsed, so I want to know how
> about update hw_ptr in ALSA.

snd_pcm_period_elapsed() calls snd_pcm_update_hw_ptr0(), which calls
your driver's .pointer callback.  The value returned by that callback
essentially is the hw_ptr (although it doesn't wrap around at the end
of the buffer).

Why do you care about hw_ptr?


Regards,
Clemens