Subject: Re: [PATCH] usb: gadget: f_fs: Fix kernel panic for SuperSpeed
To: Felipe Balbi <balbi@kernel.org>
References: <1461321780-3226-1-git-send-email-jilin@nvidia.com>
 <87bn51uagb.fsf@intel.com> <571E0058.6020007@nvidia.com>
 <87r3dtrj7b.fsf@intel.com> <571F2BA3.6040209@nvidia.com>
CC: <linux-usb@vger.kernel.org>, <linux-kernel@vger.kernel.org>
From: Jim Lin <jilin@nvidia.com>
Message-ID: <5721F0F5.9020500@nvidia.com>
Date: Thu, 28 Apr 2016 19:16:05 +0800
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On 2016年04月26日 16:49, Jim Lin wrote:
> On 2016年04月25日 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@google.com>
> 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