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

From: Jim Lin
Date: Tue Apr 26 2016 - 04:50:15 EST


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
"

--nvpublic