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From: Clemens Ladisch <clemens@ladisch.de>
To: Oleksandr Andrushchenko <andr2000@gmail.com>
Cc: alsa-devel@alsa-project.org, xen-devel@lists.xen.org,
	linux-kernel@vger.kernel.org,
	Oleksandr Andrushchenko <oleksandr_andrushchenko@epam.com>,
	tiwai@suse.com
Subject: Re: [alsa-devel] [PATCH 08/11] ALSA: vsnd: Add timer for period interrupt emulation
Date: Mon, 7 Aug 2017 15:11:49 +0200	[thread overview]
Message-ID: <4ce45eec-8657-66c4-c8c7-b851250da46a@ladisch.de> (raw)
In-Reply-To: <f2f54b55-3145-2533-c74a-9c3ea803739e@gmail.com>

Oleksandr Andrushchenko wrote:
> On 08/07/2017 01:27 PM, Clemens Ladisch wrote:
>> You have to implement period interrupts (and the .pointer callback)
>> based on when the samples are actually moved from/to the backend.
>
> Do you think I can implement this in a slightly different way,
> without a timer at all, by updating
> substream->runtime->hw_ptr_base explicitly in the frontend driver?

As far as I am aware, hw_ptr_base is an internal field that drivers
are not supposed to change.

Just use your own variable, and return it from the .pointer callback.

> So, that way, whenever I get an ack/response from the backend that it has
> successfully played the buffer

That response should come after every period.

How does that interface work?  Is it possible to change the period size,
or at least to detect what it is?


Regards,
Clemens

  reply	other threads:[~2017-08-07 13:11 UTC|newest]

Thread overview: 21+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2017-08-07  7:43 [PATCH 00/11] ALSA: vsnd: Add Xen para-virtualized frontend driver Oleksandr Andrushchenko
2017-08-07  7:43 ` [PATCH 01/11] ALSA: vsnd: Implement driver's probe/remove Oleksandr Andrushchenko
2017-08-07  7:43 ` [PATCH 02/11] ALSA: vsnd: Implement Xen bus state handling Oleksandr Andrushchenko
2017-08-07  7:43 ` [PATCH 03/11] ALSA: vsnd: Read sound driver configuration from Xen store Oleksandr Andrushchenko
2017-08-07  7:43 ` [PATCH 04/11] ALSA: vsnd: Implement Xen event channel handling Oleksandr Andrushchenko
2017-08-07  7:43 ` [PATCH 05/11] ALSA: vsnd: Implement handling of shared buffers Oleksandr Andrushchenko
2017-08-07  7:43 ` [PATCH 06/11] ALSA: vsnd: Introduce ALSA virtual sound driver Oleksandr Andrushchenko
2017-08-07  7:43 ` [PATCH 07/11] ALSA: vsnd: Initialize virtul sound card Oleksandr Andrushchenko
2017-08-07  7:43 ` [PATCH 08/11] ALSA: vsnd: Add timer for period interrupt emulation Oleksandr Andrushchenko
2017-08-07 10:27   ` [alsa-devel] " Clemens Ladisch
2017-08-07 11:30     ` Oleksandr Andrushchenko
2017-08-07 13:11       ` Clemens Ladisch [this message]
2017-08-07 13:38         ` Oleksandr Andrushchenko
2017-08-07 13:55           ` Clemens Ladisch
2017-08-07 15:14             ` Oleksandr Andrushchenko
2017-08-08  6:09               ` Oleksandr Andrushchenko
2017-08-07  7:43 ` [PATCH 09/11] ALSA: vsnd: Implement ALSA PCM operations Oleksandr Andrushchenko
2017-08-07  7:43 ` [PATCH 10/11] ALSA: vsnd: Implement communication with backend Oleksandr Andrushchenko
2017-08-07  7:43 ` [PATCH 11/11] ALSA: vsnd: Introduce Kconfig option to enable Xen PV sound Oleksandr Andrushchenko
2017-08-07 11:28 ` [PATCH 00/11] ALSA: vsnd: Add Xen para-virtualized frontend driver Takashi Sakamoto
2017-08-07 11:33   ` Oleksandr Andrushchenko

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