On Thu, Feb 26, 2015 at 11:51:11AM -0600, Bin Liu wrote:
> Felipe,
>
> On Thu, Feb 26, 2015 at 11:40 AM, Felipe Balbi <balbi@xxxxxx> wrote:
> > Hi,
> >
> > On Thu, Feb 26, 2015 at 11:20:29AM -0600, Bin Liu wrote:
> >> >> > >> > There was already a proper place where we were
> >> >> > >> > checking for babble interrupts, move babble
> >> >> > >> > recovery there.
> >> >> > >> >
> >> >> > >> > Signed-off-by: Felipe Balbi <balbi@xxxxxx>
> >> >> > >> > ---
> >> >> > >> > drivers/usb/musb/musb_core.c | 13 ++++++-------
> >> >> > >> > 1 file changed, 6 insertions(+), 7 deletions(-)
> >> >> > >> >
> >> >> > >> > diff --git a/drivers/usb/musb/musb_core.c b/drivers/usb/musb/musb_core.c
> >> >> > >> > index 2767ce1bf016..0569b24719e6 100644
> >> >> > >> > --- a/drivers/usb/musb/musb_core.c
> >> >> > >> > +++ b/drivers/usb/musb/musb_core.c
> >> >> > >> > @@ -892,6 +892,12 @@ b_host:
> >> >> > >> > } else {
> >> >> > >> > ERR("Stopping host session -- babble\n");
> >> >> > >> > musb_writeb(musb->mregs, MUSB_DEVCTL, 0);
> >> >> > >> > +
> >> >> > >> > + if (is_host_active(musb)) {
> >> >> > >> > + musb_generic_disable(musb);
> >> >> > >> > + schedule_delayed_work(&musb->recover_work,
> >> >> > >> > + msecs_to_jiffies(100));
> >> >> > >> > + }
> >> >> > >>
> >> >> > >> This change breaks babble recovery, because the following lines above here
> >> >> > >>
> >> >> > >> 873 if (devctl & (MUSB_DEVCTL_FSDEV |
> >> >> > >> MUSB_DEVCTL_LSDEV)) {
> >> >> > >> 874 dev_dbg(musb->controller, "BABBLE
> >> >> > >> devctl: %02x\n", devctl);
> >> >> > >>
> >> >> > >> have a bug - DEVCTL_FSDEV bit will be set for high-speed too, so this
> >> >> > >> 'if' traps babble handling for all cases, never hit on 'else'.
> >> >> > >
> >> >> > > We might as well drop that check altogether. Let me see what happens
> >> >> > > here.
> >> >> >
> >> >> > It is good to clean it up, but I guess the babble storm you see is
> >> >> > caused by something else. I debugged the storm last year in an older
> >> >> > kernel, it was due to the babble recovery routine does not maintain a
> >> >> > bit in MUSB_BABBLE_CTL, though I forgot the details now. I am looking
> >> >> > at this part in the upstream kernel right now.
> >>
> >> I am unable to recall why this bug causes the storm, but here is the
> >> bug fix - SW_SESSION_CTRL bit gets cleared after reset. Please let me
> >> know if I need to send an seperate patch email.
> >
> > please send it as a patch, but please rebase on top of my testing/next.
> > I've just pushed quite a few patches fixing a bunch of weird
> > inconsistencies with babble recovery.
>
> I can do that. But the hw reset is unnecessary for babble recover, it
> is also a problem due to AM335x Errata Adversary 1.0.34. If not reset,
> SW_SESSION_CTRL bit will not be cleared.
>
> Do you want me to send this patch or a new patch to not reset hw in recovery?
I would rather not reset the IP if we don't have to :-s
--
balbi
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