lkml.org 
[lkml]   [2016]   [Apr]   [27]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
/
From
SubjectRE: [PATCH] usb: dwc3: usb/dwc3: fake dissconnect event when turn off pullup
Date
Hi, Balbi,

The step to reproduce this issue is:
1) connect device to a host and wait its enumeration.
2) trigger software disconnect by calling function
usb_gadget_disconnect(), which finally call
dwc3_gadget_pullup(false). Do not reconnect device
(I mean no enumeration go on, keep bit Run/Stop 0.).

At here, gadget driver's disconnect callback should be
Called, right? We has been disconnected. But no, as
You said " not generating disconnect IRQ after you
drop Run/Stop is expected".

And I am testing on an Android device, Android only
use dwc3_gadget_pullup(false) to issue a soft disconnection.
This confused user that the UI still show usb as connected
State, caused by missing a disconnect event.

> Hi,
>
> changbin.du@intel.com writes:
> > From: "Du, Changbin" <changbin.du@intel.com>
> >
> > The dwc3 controller can't generate a disconnect event after it is
> > stopped. Thus gadget dissconnect callback is not invoked when do
>
> not generating disconnect IRQ after you drop Run/Stop is expected.
>
> > soft dissconnect. Call dissconnect here to workaround this issue.
>
> I'm rather sure this is a bug elsewhere. How do you trigger this ?
>
> > Note, most time we still see disconnect be called that because
> > it is invoked by dwc3_gadget_reset_interrupt(). But if we
> > disconnect cable once pullup disabled quickly, issue can be
> > observed.
>
> I can't understand what you're trying to say with this.
>
> > Signed-off-by: Du, Changbin <changbin.du@intel.com>
> > ---
> > drivers/usb/dwc3/gadget.c | 33 ++++++++++++++++++++++++---------
> > 1 file changed, 24 insertions(+), 9 deletions(-)
> >
> > diff --git a/drivers/usb/dwc3/gadget.c b/drivers/usb/dwc3/gadget.c
> > index 8e4a1b1..cd73187 100644
> > --- a/drivers/usb/dwc3/gadget.c
> > +++ b/drivers/usb/dwc3/gadget.c
> > @@ -1566,6 +1566,15 @@ static int dwc3_gadget_run_stop(struct dwc3
> *dwc, int is_on, int suspend)
> > return 0;
> > }
> >
> > +static void dwc3_disconnect_gadget(struct dwc3 *dwc)
> > +{
> > + if (dwc->gadget_driver && dwc->gadget_driver->disconnect) {
> > + spin_unlock(&dwc->lock);
> > + dwc->gadget_driver->disconnect(&dwc->gadget);
> > + spin_lock(&dwc->lock);
> > + }
> > +}
> > +
> > static int dwc3_gadget_pullup(struct usb_gadget *g, int is_on)
> > {
> > struct dwc3 *dwc = gadget_to_dwc(g);
> > @@ -1575,6 +1584,21 @@ static int dwc3_gadget_pullup(struct usb_gadget
> *g, int is_on)
> > is_on = !!is_on;
> >
> > spin_lock_irqsave(&dwc->lock, flags);
> > + /**
> > + * WORKAROUND: The dwc3 controller can't generate a disconnect
> > + * event after it is stopped. Thus gadget dissconnect callback
> > + * is not invoked when do soft dissconnect. Call dissconnect
> > + * here to workaround this issue.
> > + * Note, most time we still see disconnect be called that because
> > + * it is invoked by dwc3_gadget_reset_interrupt(). But if we
> > + * disconnect cable once pullup disabled quickly, issue can be
> > + * observed.
> > + */
> > + if (!is_on && (dwc->gadget.speed != USB_SPEED_UNKNOWN)) {
> > + dev_dbg(dwc->dev, "fake dissconnect event on pullup
> off\n");
> > + dwc3_disconnect_gadget(dwc);
> > + dwc->gadget.speed = USB_SPEED_UNKNOWN;
> > + }
>
> this is *really* wrong. You shouldn't be calling pullup directly. This
> patch looks wrong and you didn't even explain how to trigger this
> problem; when does the problem happen ?
>
> Gadget load/unload does the right thing here, so that can't be the
> case. We also do the right thing on soft_connect sysfs file:
>
> static ssize_t usb_udc_softconn_store(struct device *dev,
> struct device_attribute *attr, const char *buf, size_t n)
> {
> struct usb_udc *udc = container_of(dev, struct usb_udc,
> dev);
>
> if (!udc->driver) {
> dev_err(dev, "soft-connect without a gadget driver\n");
> return -EOPNOTSUPP;
> }
>
> if (sysfs_streq(buf, "connect")) {
> usb_gadget_udc_start(udc);
> usb_gadget_connect(udc->gadget);
> } else if (sysfs_streq(buf, "disconnect")) {
> usb_gadget_disconnect(udc->gadget);
> udc->driver->disconnect(udc->gadget);
> usb_gadget_udc_stop(udc);
> } else {
> dev_err(dev, "unsupported command '%s'\n", buf);
> return -EINVAL;
> }
>
> return n;
> }
> static DEVICE_ATTR(soft_connect, S_IWUSR, NULL,
> usb_udc_softconn_store);
>
> So really, what _is_ the problem ?
>
> --
> balbi

\
 
 \ /
  Last update: 2016-04-27 13:41    [W:0.037 / U:1.016 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site