Re: [PATCH] usb: musb: Force-disable pullup on shutdown

[Paul Cercueil]

Le mer. 3 avril 2019 à 17:46, Bin Liu <b-liu@xxxxxx> a écrit :
> On Wed, Apr 03, 2019 at 05:31:31PM +0200, Paul Cercueil wrote:
> >  Le mer. 3 avril 2019 à 15:26, Bin Liu <b-liu@xxxxxx> a écrit :
> >  >On Tue, Apr 02, 2019 at 09:58:42PM +0200, Paul Cercueil wrote:
> >  >> Hi,
> >  >>
> >  >> Le lun. 1 avril 2019 à 20:20, Bin Liu <b-liu@xxxxxx> a écrit :
> >  >> >On Mon, Apr 01, 2019 at 07:46:22PM +0200, Paul Cercueil wrote:
> >  >> >>
> >  >> >>
> >  >> >> Le lun. 1 avril 2019 à 19:17, Bin Liu <b-liu@xxxxxx> a 
> > écrit :
> >  >> >> >On Thu, Mar 21, 2019 at 03:42:46PM +0100, Paul Cercueil 
> > wrote:
> >  >> >> >> When the musb is shutdown, for instance when the driver is
> >  >> >>unloaded,
> >  >> >> >> force-disable the pullup. Otherwise, the host will still 
> > see
> >  >> >> >>the gadget
> >  >> >> >> device even after the shutdown.
> >  >> >> >
> >  >> >> >how would this happen?
> >  >> >> >
> >  >> >> >when musb-hdrc driver is unloaded, udc core removes the bound
> >  >> >>gadget
> >  >> >> >driver which calls musb_gadget_pullup() to disable the 
> > pullup.
> >  >> >>
> >  >> >> I'm testing with the jz4740-musb driver. I don't unload the
> >  >> >>module (it's
> >  >> >> built-in) but unbind it from sysfs.
> >  >> >
> >  >> >I did unbind too.
> >  >> >
> >  >> >root@am335x-evm:/sys/bus/platform/drivers/musb-hdrc# echo
> >  >> >musb-hdrc.0 > unbind
> >  >> >
> >  >> >or unbind the glue driver:
> >  >> >
> >  >> >root@am335x-evm:/sys/bus/platform/drivers/musb-dsps# echo
> >  >> >47401400.usb > unbind
> >  >> >
> >  >> >musb_gadget_pullup() is called in both cases.
> >  >> >
> >  >> >[ 3880.597014] [<bf444ab0>] (musb_gadget_pullup [musb_hdrc]) 
> > from
> >  >> >[<bf402cbc>] (usb_gadget_disconnect+0x3c/0xf4 [udc_core])
> >  >> >[ 3880.607959] [<bf402cbc>] (usb_gadget_disconnect [udc_core])
> >  >> >from [<bf403b28>] (usb_gadget_remove_driver+0x4c/0x90 
> > [udc_core])
> >  >> >[ 3880.619338] [<bf403b28>] (usb_gadget_remove_driver 
> > [udc_core])
> >  >> >from [<bf403d20>] (usb_del_gadget_udc+0x5c/0xc0 [udc_core])
> >  >>
> >  >> In my case this stops here, usb_del_gadget_udc() does not call
> >  >> usb_gadget_remove_driver(), that's why the pullup is never 
> > disabled.
> >  >>
> >  >> I guess that's because udc->driver is NULL; I'm testing with
> >  >
> >  >then the pullup should be disable by now.
> >  >
> >  >> CONFIG_USB_CONFIGFS,
> >  >> and I don't configure anything in sysfs before unbinding the 
> > driver.
> >  >
> >  >I didn't check on this, but I could imagine that
> >  >- when a configfs gadget is bound to the udc, .pullup() is called;
> >  >- when the configfs gadget is unbound from the udc, .pullup should 
> > be
> >  >  called again to disable the pullup.
> >
> >  An important thing that I did not mention, is that the SoC boots
> >  from USB,
> >  so the pullup is active before the musb driver loads. Since in my 
> > case a
>
> It sounds to me that the musb driver should disable the pullup during
> init.  Isn't it?

Yes. I can move it to musb_gadget_setup(). Should I still protect it 
with
the spinlock then?

> >  configfs gadget is never bound, then .pullup() is never called, and 
> > when
> >  I unbind the driver the pullup is still enabled.
>
> Regards,
> -Bin.