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


Le mer. 3 avril 2019 à 15:26, Bin Liu <b-liu@ti.com> 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@ti.com> 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@ti.com> 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
configfs gadget is never bound, then .pullup() is never called, and when
I unbind the driver the pullup is still enabled.

-Paul


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