From: Clemens Ladisch <clemens@ladisch.de>
To: Fanchao Liu <liufc10@gmail.com>
Cc: alsa-devel@alsa-project.org
Subject: Re: HDA driver without interrupt
Date: Thu, 03 May 2012 10:37:52 +0200 [thread overview]
Message-ID: <4FA243E0.10506@ladisch.de> (raw)
In-Reply-To: <CAOAAS1z7iA2excEt9cE45CBmQs=XUkigW6+A94zyp2BuRLBBcA@mail.gmail.com>
Fanchao Liu wrote:
> It can transfer data via DMA,the problem is I don't know when to
> update hw_ptr and other pointers without interrupt.
Does the hardware have some other means to at least read the current
position?
> I set a timer and call snd_pcm_period_elapsed() every 50ms but get
> underrun error.
With a call to snd_pcm_period_elapsed(), the driver guarantees that the
current position is at or after the next period boundary.
Regards,
Clemens
prev parent reply other threads:[~2012-05-03 8:33 UTC|newest]
Thread overview: 4+ messages / expand[flat|nested] mbox.gz Atom feed top
2012-05-02 12:54 HDA driver without interrupt liufc
2012-05-02 19:28 ` Pierre-Louis Bossart
2012-05-03 6:13 ` Clemens Ladisch
[not found] ` <CAOAAS1z7iA2excEt9cE45CBmQs=XUkigW6+A94zyp2BuRLBBcA@mail.gmail.com>
2012-05-03 8:37 ` Clemens Ladisch [this message]
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