Re: snd-usb: "delay: estimated 0, actual 352"

From: Takashi Iwai <tiwai@suse.de>
To: Markus Trippelsdorf <markus@trippelsdorf.de>
Cc: Daniel Mack <zonque@gmail.com>,
	Linus Torvalds <torvalds@linux-foundation.org>,
	linux-kernel@vger.kernel.org, alsa-devel@alsa-project.org,
	Pierre-Louis Bossart <pierre-louis.bossart@linux.intel.com>
Subject: Re: snd-usb: "delay: estimated 0, actual 352"
Date: Thu, 06 Sep 2012 16:31:24 +0200	[thread overview]
Message-ID: <s5hharbxlxf.wl%tiwai@suse.de> (raw)
In-Reply-To: <20120906131758.GA256@x4>

At Thu, 6 Sep 2012 15:17:58 +0200,
Markus Trippelsdorf wrote:
> 
> On 2012.09.06 at 15:08 +0200, Takashi Iwai wrote:
> > At Thu, 6 Sep 2012 11:43:48 +0200,
> > Markus Trippelsdorf wrote:
> > > 
> > > On 2012.09.06 at 10:21 +0200, Takashi Iwai wrote:
> > > > At Thu, 06 Sep 2012 09:35:26 +0200,
> > > > Takashi Iwai wrote:
> > > > 
> > > > In short, a patch like below may fix the issue (note: completely
> > > > untested!)
> > > 
> > > No it doesn't, unfortunately...
> > 
> > OK, I start tracking down the problem a bit more deeply now.
> > 
> > The issue happens when the first two URBs are passed to
> > retire_playback_urb().  These are URBs filled before start_endpoints()
> > are set, so they contain actually zero size.  Even though these are
> > a sort of dummy packets, the driver still tries to check with the
> > queued delay account, and gives bogus errors.
> > 
> > So, essentially the messages are harmless and nothing to worry too
> > much, but surely it doesn't look sexy.
> > 
> > The patch below should fix the problem.  Please give it a try.
> 
> Yes, your patch finally fixes the problem. 
> Thank you Takashi-san.

Thanks for your quick test!

If Daniel has no objection with that patch, I'm going to merge it.

Takashi