Re: [PATCH] Revert "usb: dwc3: gadget: drop unnecessary loop when cleaning up TRBs"

["Ville Syrjälä" <ville.syrjala@linux.intel.com>]

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On Mon, Aug 31, 2015 at 01:50:10PM -0500, Felipe Balbi wrote:
> Hi,
> 
> On Mon, Aug 31, 2015 at 08:25:10PM +0300, Ville Syrj�l� wrote:
> > On Mon, Aug 31, 2015 at 11:54:13AM -0500, Felipe Balbi wrote:
> > > On Mon, Aug 31, 2015 at 07:48:28PM +0300, ville.syrjala@linux.intel.com wrote:
> > > > From: Ville Syrj�l� <ville.syrjala@linux.intel.com>
> > > > 
> > > > This reverts commit 8f2c9544aba636134303105ecb164190a39dece4.
> > > > 
> > > > As it breaks g_ether on my Baytrail FFRD8 device. Everything starts out
> > > > fine, but after a bit of data has been transferred it just stops
> > > > flowing.
> > > > 
> > > > Note that I do get a bunch of these "NOHZ: local_softirq_pending 08"
> > > > when booting the machine, but I'm not really sure if they're related
> > > > to this problem.
> > > 
> > > I have a feeling your problem is elsewhere. We *are* completing one TRB
> > > at a time. By reverting that commit you're just masking the real problem
> > > and I'd rather get that one fixed.
> > > 
> > > How do you reproduce your issue ?
> > 
> > Just boot the system, it gets an IP from dnsmasq on my host, then I ssh
> > into it and do something to produce a bit of console output, after which
> > g_ether is dead. Eg. 'dmesg' a few times is enough to kill it.
> 
> which kernel version ?

Anything since the patch went in, so 4.1-rc<something>

> Running as USB2 or USB3 ?

speed:480, so USB2 I presume?

> Have you tried
> linux-next ?

Tried it now (next-20150901). Equally bad as the rest.

> I just did 1000 dmesg iterations over ssh with g_ether and
> saw no issues.
> 
> Can you enable dwc3 tracepoints and try again ? (use some very large
> trace buffer, something around 2 or 4 MiB should be enough).

Attached one trace from linux-next, and another one with the revert on
top.

-- 
Ville Syrj�l�
Intel OTC

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