On Thu, Feb 26, 2015 at 10:37:50AM -0600, Bin Liu wrote:
> Felipe,
>
> On Thu, Feb 26, 2015 at 10:31 AM, Felipe Balbi <balbi@xxxxxx> wrote:
> > On Thu, Feb 26, 2015 at 10:21:38AM -0600, Bin Liu wrote:
> >> Felipe,
> >>
> >> On Thu, Feb 26, 2015 at 9:07 AM, Felipe Balbi <balbi@xxxxxx> 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.
alright, I'll have a look, let's see.
--
balbi
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