linux-kernel - Re: [PATCH] usb: musb: Disable pullup in gadget setup

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Message-Id: <1563170740.1702.0@crapouillou.net>
Date:   Mon, 15 Jul 2019 02:05:40 -0400
From:   Paul Cercueil <paul@...pouillou.net>
To:     Bin Liu <b-liu@...com>
Cc:     od@...c.me, linux-usb@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH] usb: musb: Disable pullup in gadget setup

Hi Bin,


Le mar. 30 avril 2019 à 11:05, Bin Liu <b-liu@...com> a écrit :
> Hi Paul,
> 
> On Thu, Apr 04, 2019 at 11:10:46AM -0500, Bin Liu wrote:
>>  On Thu, Apr 04, 2019 at 11:37:43AM +0200, Paul Cercueil wrote:
>>  > The pullup may be already enabled before the driver is 
>> initialized.
>>  > It has to be disabled at init time, as we cannot guarantee that a 
>> gadget
>>  > driver will be bound to the UDC.
>>  >
>>  > Signed-off-by: Paul Cercueil <paul@...pouillou.net>
>>  > ---
>>  >  drivers/usb/musb/musb_gadget.c | 1 +
>>  >  1 file changed, 1 insertion(+)
>>  >
>>  > diff --git a/drivers/usb/musb/musb_gadget.c 
>> b/drivers/usb/musb/musb_gadget.c
>>  > index ffe462a657b1..094dc59c834c 100644
>>  > --- a/drivers/usb/musb/musb_gadget.c
>>  > +++ b/drivers/usb/musb/musb_gadget.c
>>  > @@ -1794,6 +1794,7 @@ int musb_gadget_setup(struct musb *musb)
>>  >
>>  >  	musb->is_active = 0;
>>  >  	musb_platform_try_idle(musb, 0);
>>  > +	musb_pullup(musb, 0);
>>  >
>>  >  	status = usb_add_gadget_udc(musb->controller, &musb->g);
>>  >  	if (status)
>> 
>>  Applied.
> 
> Sorry, I have dropped this patch from my tree. I realized the gadget
> core already defines callbacks to control the pullup. I think the
> proper fix should be calling usb_udc_vbus_handler() in musb gadget or
> glue layers.
> 
> -Bin.

usb_udc_vbus_handler() requires a usb_gadget *, I don't see where I can
get that from the struct musb.

Besides, the point is to have the pullup disabled before a gadget is 
bound,
so I don't understand why you suggest that?

-Paul