Re: [PATCH] usb: gadget: f_fs: Fix kernel panic for SuperSpeed

[Jim Lin]

On 2016å04æ26æ 16:49, Jim Lin wrote:
> On 2016å04æ25æ 20:01, Felipe Balbi wrote:
> > * PGP Signed by an unknown key
> >
> >
> >
> >
> > > > Is this happening on set_config() ? If that's the case, why is
> > > > gadget->speed set to USB_SPEED_SUPER to start with ? Your controller
> > > > should already have negotiated highspeed which means
> > > > function_descriptors() should have returned highspeed descriptors, 
> > > > not a
> > > > NULL superspeed.
> > > >
> > > > Care to explain why you haven't negotiated Highspeed ? The only 
> > > > thing I
> > > > can think of is that you're using a Superspeed-capable peripheral
> > > > controller (dwc3?) with maximum-speed set to Superspeed, with a
> > > > Superspeed-capable cable connected to an XHCI PC, but loading a
> > > > high-speed gadget driver (which you got from Android, written with 
> > > > f_fs)
> > > > and this gadget doesn't tell composite that its maximum speed is
> > > > Highspeed, instead of super-speed.
> > > >
> > > > We can add a check, sure, to avoid a kernel oops; however, you should
> > > > really fix up the gadget implementation and/or set dwc3's 
> > > > maximum-speed
> > > > property accordingly.
> > > >
> > > > Can you check if this patch makes your scenario work while still being
> > > > fully functional ?
> > > >
> > > > diff --git a/drivers/usb/gadget/composite.c 
> > > > b/drivers/usb/gadget/composite.c
> > > > index de9ffd60fcfa..3d3cdc5ed20d 100644
> > > > --- a/drivers/usb/gadget/composite.c
> > > > +++ b/drivers/usb/gadget/composite.c
> > > > @@ -66,20 +66,36 @@ function_descriptors(struct usb_function *f,
> > > >    {
> > > >        struct usb_descriptor_header **descriptors;
> > > >    +    /*
> > > > +     * NOTE: we try to help gadget drivers which might not be setting
> > > > +     * max_speed appropriately.
> > > > +     */
> > > > +
> > > >        switch (speed) {
> > > >        case USB_SPEED_SUPER_PLUS:
> > > >            descriptors = f->ssp_descriptors;
> > > > -        break;
> > > > +        if (descriptors)
> > > > +            break;
> > > > +        /* FALLTHROUGH */
> > > >        case USB_SPEED_SUPER:
> > > >            descriptors = f->ss_descriptors;
> > > > -        break;
> > > > +        if (descriptors)
> > > > +            break;
> > > > +        /* FALLTHROUGH */
> > > >        case USB_SPEED_HIGH:
> > > >            descriptors = f->hs_descriptors;
> > > > -        break;
> > > > +        if (descriptors)
> > > > +            break;
> > > > +        /* FALLTHROUGH */
> > > >        default:
> > > >            descriptors = f->fs_descriptors;
> > > >        }
> > > >    +    /*
> > > > +     * if we can't find any descriptors at all, then this gadget 
> > > > deserves to
> > > > +     * Oops with a NULL pointer dereference
> > > > +     */
> > > > +
> > > >        return descriptors;
> > > >    }
> > > After trying your change, no kernel panic, but SuperSpeed device 
> > > (device
> > > mode) is not enumerated by ubuntu 14.04 USB 3.0 host controller as MTP
> > > device with USB3.0 cable.
> > what do you get on dmesg on host side ? Are you running dwc3 ? If you
> > are, please capture trace logs of the failure:
> >
> > # mount -t debugfs none /sys/kernel/debug
> > # cd /sys/kernel/debug/tracing
> > # echo 2048 > buffer_size_kb
> > # echo 1 > events/dwc3/enable
> >
> > (now connect your cable to host pc)
> >
> > # cp trace /path/to/non-volatile/storage/trace.txt
> >
> > Please reply with this trace.txt file and dmesg from host side.
> This is not running with dwc3.
>
> dmesg from PC host side (after adding your change without my patch):
>
> [17907.984647] usb 6-2: new SuperSpeed USB device number 54 using 
> xhci_hcd
> [17908.012036] usb 6-2: No SuperSpeed endpoint companion for config 1  
> interface 1 altsetting 0 ep 2: using minimum values
> [17908.012040] usb 6-2: No SuperSpeed endpoint companion for config 1  
> interface 1 altsetting 0 ep 131: using minimum values
> [17908.013652] usb 6-2: New USB device found, idVendor=xxxx, 
> idProduct=xxxx
> [17908.013656] usb 6-2: New USB device strings: Mfr=1, Product=2, 
> SerialNumber=3
> [17908.013658] usb 6-2: Product: xxxxxxx
> [17908.013661] usb 6-2: Manufacturer: xxxxxx
> [17908.013664] usb 6-2: SerialNumber: 1234567890
> [17908.014680] xhci_hcd 0000:05:00.0: ERROR: unexpected command 
> completion code 0x11.
> [17908.014690] usb 6-2: can't set config #1, error -22
>
> I also attach git log of system/core/adb/usb_linux_client.cpp of 
> Android N for your reference.
> "
> Author: Badhri Jagan Sridharan <Badhri@xxxxxxxxxx>
> Date:   Mon Oct 5 13:04:03 2015 -0700
>
>     adbd: Add os descriptor support for adb.
>
>     Eventhough windows does not rely on extended os
>     descriptor for adbd, when android usb device is
>     configures as a composite device such as mtp+adb,
>     windows discards the extended os descriptor even
>     if one of the USB function fails to send
>     the extended compat descriptor. This results in automatic
>     install of MTP driverto fail when Android device is in
>     "File Transfer" mode with adb enabled.
>
> https://msdn.microsoft.com/en-us/library/windows/hardware/gg463179.aspx
> "
How do we proceed on this patch?
 [PATCH] usb: gadget: f_fs: Fix kernel panic for SuperSpeed

Thanks,
--nvpublic