From: Clemens Ladisch <clemens@ladisch.de>
To: alsa-devel@alsa-project.org
Cc: tova-dev@tovacompany.com, linux-usb@vger.kernel.org,
Joe Rayhawk <jrayhawk@fairlystable.org>,
alsa-devel@vger.kernel.org
Subject: Re: [alsa-devel] BUG: USB audio discontinuities with 'UHCI: implement new semantics for URB_ISO_ASAP'
Date: Fri, 19 Apr 2013 18:25:46 +0200 [thread overview]
Message-ID: <5171700A.50308@ladisch.de> (raw)
In-Reply-To: <Pine.LNX.4.44L0.1304191132130.21363-100000@netrider.rowland.org>
Alan Stern wrote:
> ...
> This trace shows that the frame numbers do not increase sequentially:
> 1057125, 1057126, 1057128, 1057129, 1053131, ... This is because the
> new driver is a little more conservative than the old driver,
> requiring latencies to be larger than 1 ms. You can see this
> explicitly in one of the new lines added by the commit you found:
>
> + next = uhci->frame_number + 2;
>
> That 2 is the minimum latency, in frames (one frame per ms).
One frame worked fine with the old driver. What is the reason for
this regression?
> Anyway, the solution is simple: The audio driver needs either to submit
> buffers that are at least 2 ms long, or to use more than two buffers
> (or both).
The audio driver already has the infrastructure to cope for hardware
restrictions like this, it just needs to *know* about them. How can
it detect that it runs on the OHCI/UHCI drivers?
Regards,
Clemens
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next prev parent reply other threads:[~2013-04-19 16:25 UTC|newest]
Thread overview: 23+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <20130417183436.GA4381@richardiv.omgwallhack.org>
2013-04-18 16:42 ` [alsa-devel] BUG: USB audio discontinuities with 'UHCI: implement new semantics for URB_ISO_ASAP' Alan Stern
2013-04-18 21:23 ` Joe Rayhawk
2013-04-18 21:23 ` [alsa-devel] " Joe Rayhawk
2013-04-19 15:57 ` Alan Stern
2013-04-19 16:25 ` Clemens Ladisch
2013-04-19 16:25 ` Clemens Ladisch [this message]
2013-04-19 18:18 ` Alan Stern
2013-04-19 18:18 ` [alsa-devel] " Alan Stern
2013-04-20 0:35 ` Joe Rayhawk
2013-04-22 15:29 ` Alan Stern
2013-04-23 8:47 ` Clemens Ladisch
2013-04-23 8:47 ` [alsa-devel] " Clemens Ladisch
2013-04-23 14:58 ` Alan Stern
2013-04-23 14:58 ` [alsa-devel] " Alan Stern
2013-04-23 15:09 ` Clemens Ladisch
2013-04-23 15:09 ` [alsa-devel] " Clemens Ladisch
2013-04-23 15:23 ` Alan Stern
2013-04-23 15:23 ` [alsa-devel] " Alan Stern
2013-04-22 15:29 ` Alan Stern
2013-04-20 0:35 ` Joe Rayhawk
2013-04-19 15:57 ` Alan Stern
2013-04-18 16:42 ` Alan Stern
[not found] <20130509001613.GA4383@richardiv.omgwallhack.org>
2013-05-09 14:38 ` [alsa-devel] " Alan Stern
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