Re: out of sync capture samples with MMAP on MIPS

From: Takashi Iwai <tiwai@suse.de>
To: Daniel Danzberger <daniel@dd-wrt.com>
Cc: alsa-devel@alsa-project.org
Subject: Re: out of sync capture samples with MMAP on MIPS
Date: Tue, 29 May 2018 10:02:42 +0200	[thread overview]
Message-ID: <s5hmuwiq47x.wl-tiwai@suse.de> (raw)
In-Reply-To: <9554b45e-2918-19a0-8dec-8b131b3b6ab8@dd-wrt.com>

On Tue, 29 May 2018 09:55:44 +0200,
Daniel Danzberger wrote:
> 
> On 05/27/2018 01:08 PM, Takashi Iwai wrote:
> > On Sun, 27 May 2018 11:34:07 +0200,
> > Daniel Danzberger wrote:
> >>
> >> On 05/25/2018 02:20 PM, Takashi Iwai wrote:> It's likely because of the cache
> >> coherency issue on ARM.
> >>> Currently USB-audio driver uses the buffer via vmalloc() for the
> >>> intermediate buffer, and this may go out of sync on non-coherent arch
> >>> like ARM.
> >>>
> >>> Does the patch below help?  Not sure whether it works on ARM at all,
> >>> as I've tested only on x86.
> >> Your patch works. I cannot reproduce the issue anymore. Thanks.
> > 
> > Good to hear.  Below is the revised version, so that the behavior can
> > be controlled via use_vmalloc option for snd-usb-audio module.
> > Could you check whether this still works?
> 
> it works.

OK, I'll queue the patch for 4.18.

thanks,

Takashi