Re: [PATCH v4 1/6] usb: musb: core: Handle Babble condition only in HOST mode

[George Cherian]

On 5/23/2014 2:12 AM, Bin Liu wrote:
> Hi George,
>
> On Mon, May 19, 2014 at 11:32 PM, George Cherian <george.cherian@xxxxxx> wrote:
> > Hi Bin,
> >
> > On 5/19/2014 9:24 PM, Bin Liu wrote:
> > > Hi,
> > >
> > > On Mon, May 19, 2014 at 8:39 AM, George Cherian <george.cherian@xxxxxx>
> > > wrote:
> > > > BABBLE and RESET share the same interrupt. The interrupt
> > > > is considered to be RESET if MUSB is in peripheral mode and
> > > > as a BABBLE if MUSB is in HOST mode.
> > > >
> > > > Handle babble condition iff MUSB is in HOST mode.
> > > >
> > > > Signed-off-by: George Cherian <george.cherian@xxxxxx>
> > > > ---
> > > >    drivers/usb/musb/musb_core.c | 2 +-
> > > >    1 file changed, 1 insertion(+), 1 deletion(-)
> > > >
> > > > diff --git a/drivers/usb/musb/musb_core.c b/drivers/usb/musb/musb_core.c
> > > > index 61da471..eff3c5c 100644
> > > > --- a/drivers/usb/musb/musb_core.c
> > > > +++ b/drivers/usb/musb/musb_core.c
> > > > @@ -849,7 +849,7 @@ b_host:
> > > >           }
> > > >
> > > >           /* handle babble condition */
> > > > -       if (int_usb & MUSB_INTR_BABBLE)
> > > > +       if (int_usb & MUSB_INTR_BABBLE && is_host_active(musb))
> > > >                   schedule_work(&musb->recover_work);
> > > I guess my following comments are for Daniel's patch as while which
> > > initially added the babble work.
> > >
> > > Should this if statement be merged into the previous 'if(int_usb &
> > > MUSB_INTR_RESET)' one, which handles the same interrupt and already
> > > handles host and device mode respectively.
> >
> > Initially I too had the babble handling as part of  'if(int_usb &
> > MUSB_INTR_RESET)'
> > one. But during my tests I hit a corner case where in we hit a BABBLE
> > condition
> > on disconnect. In such case the babble interrupt can be handled only if we
> > have a seperate
> > check, else its considered as a BUS RESET.
> >
> > When all devices are disconnected  MUSB_DEVCTL_HM = 0 and the code always
> > enter the
> > else path. In this path it treats the BABBLE as a BUS RESET.
> The code flow is a bit confusing, two if() handle the same interrupt.
> The second one implied using 'handled = IRQ_HANDLED;' from the first
> one.
> Also does the switch() in else{} in the first if() cause any side effect?
No it doesn't.
> Since this babble handing is AM335x specific, how about handle it in
> dsps_interrupt() in musb_dsps.c, which already has an entry for babble
> interrupt? TI 3.2 kernel does this way.
That the reason we have platform specific callbacks added  from the main 
interrupt handler.
> Regards,
> -Bin.
>
> > > Regards,
> > > -Bin.
> > >
> > > >    #if 0
> > > > --
> > > > 1.8.3.1
> > > >
> > > > --
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> > > > the body of a message to majordomo@xxxxxxxxxxxxxxx
> > > > More majordomo info at  http://vger.kernel.org/majordomo-info.html
> >
> >
> > --
> > -George


--
-George

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