On Wed, Jan 18, 2017 at 10:44:32AM -0800, Tony Lindgren wrote:
> * Tony Lindgren <tony@xxxxxxxxxxx> [170118 10:15]:
> > * Grygorii Strashko <grygorii.strashko@xxxxxx> [170118 10:05]:
> > >
> > >
> > > On 01/18/2017 10:53 AM, Tony Lindgren wrote:
> > > > Hi,
> > > >
> > > > * Bin Liu <b-liu@xxxxxx> [170118 06:26]:
> > > >> With this v3, I still get -71 error when a device is plugged to a hub to
> > > >> musb. It doesn't happen though if the device is already plugged to the hub
> > > >> before attaching the hub to musb.
> > > >>
> > > >> [ 177.579300] usb 1-1: reset high-speed USB device number 2 using musb-hdrc
> > > >> [ 177.719308] usb 1-1: device descriptor read/64, error -71
> > > >> [ 178.350297] usb 1-1.1: new high-speed USB device number 4 using musb-hdrc
> > > >
> > > > I think the -71 issue is a different regression. I've verified that v4.8.y
> > > > does not have this, but v4.9.y does have it.
> > > >
> > > > So far the easiest way for me to reproduce the -71 problem is by plugging
> > > > a USB drive into a connected hub. If I connect the hub with USB drive already
> > > > plugged into the hub, it does not happen.
> ...
>
> > > Sry, but wouldn't be more simple and safe just to drop PM runtime from this driver,
> > > as it is part of musb and musb PM state expected to be handled properly by PM runtime now.
> >
> > Well we still need PM runtime in cppi41 to initialize it when it gets
> > probed and idle it when not used even if musb modules are not loaded.
> >
> > Unfortunately until musb_cppi41.c dma calls are fixed, we can't do
> > any sane use counting in cppi41.c without adding timeout handling
> > to it.
> >
> > > More over, There is another possibility related to the current PM runtime implementation and autosuspend
> > > - it might introduce delay between time when musb request desc push and time when cppi will actually
> > > put this desc in HW queue if cppi was not active.
> > > For example, there might not be -71 error seen if CPPI autosuspend is disabled
> > > (cppi is active all the time) before plug-in hub and then USB drive.
> >
> > I already checked that. The -71 error seems to be a separate issue.
>
> OK found it. I can make v4.8.17 produce -71 errors with just commit
> 467d5c980709 ("usb: musb: Implement session bit based runtime PM for
> musb-core") applied on top of it. So looks like we're missing some
> musb quirk handling for the devctl session bit.
Nice!
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