Possible USB Mass Storage bug on Xilinx's Zynq

[Bruno L. Albrecht]

Hello people,
it's my first post here, so forgive me if I do something wrong. I'll try to
be short and clear.

I'm developing on an Avnet PicoZed (based on a Xilinx Zynq SoC) and my
objective is to expose the eMMC as a Mass Storage Device over an USB
Connection.

I used the following config flag on defconfig file (
https://github.com/Xilinx/u-boot-xlnx/blob/master/configs/xilinx_zynq_virt_defconfig
):

CONFIG_CMD_USB_MASS_STORAGE=y


To the Device Tree (
https://github.com/Xilinx/u-boot-xlnx/blob/master/arch/arm/dts/zynq-picozed.dts)
I added the usb configuration:

aliases {
>         <...>
>         usb0 = &usb0;
> };
> &usb0 {
>         u-boot,dm-pre-reloc;
>         status = "okay";
>         dr_mode = "peripheral";
> };


Compilation goes fine and U-Boot boots fine. The eMMC is correctly
recognized.
Then I use the following command to initiate the USB Mass Storage:

ums 0 mmc 0


When on *Windows*, the command is successful for a brief moment and then
the board resets with the following error:

Zynq> ums 0 mmc 0
> UMS: LUN 0, dev 0, hwpart 0, sector 0x0, count 0xe30000
> \EP1/in FAIL info=40000080 pg0=3eb393c0
> EP1/in FAIL info=40008080 pg0=3eb3d3c0
> EP1/in FAIL info=d8080 pg0=3eaebdc0
> CACHE: Misaligned operation at range [00000001, 00000041]
> CACHE: Misaligned operation at range [00000001, 00000041]
> data abort
> pc : [<3ff67dec>]          lr : [<3ff67dec>]
> reloc pc : [<0405cdec>]    lr : [<0405cdec>]
> sp : 3eae81f0  ip : 00000031     fp : 3ffd957c
> r10: 00000001  r9 : 3eaeaed0     r8 : 00000001
> r7 : 3ffd9524  r6 : 00000001     r5 : 3ffd94ec  r4 : 3ffd95a4
> r3 : e0001000  r2 : 00000001     r1 : 00000041  r0 : 00000001
> Flags: nZCv  IRQs off  FIQs off  Mode SVC_32
> Code: eaffff7e e2861040 e1a00006 ebfe91a6 (e5963004)
> Resetting CPU ...
>

Since I'm working on a Windows machine, I have a Ubuntu running on a
Virtual Machine (VirtualBox). So I made a rule to bypass the USB device
that would be created on Windows directly to the Virtual Machine (virtually
connected the USB device to my Ubuntu).

When I do this, the command works. I can access the eMMC and format it and
do whatever I want. If I remove the filter and let Windows enumerate the
device, the board resets again.

I took a look at the dmesg messages on Ubuntu and found the following (the
only unusual messages are in bold):

[101436.784042] usb 1-2: new full-speed USB device number 25 using ohci-pci
>
> *[101437.232208] usb 1-2: config 1 interface 0 altsetting 0 endpoint 0x81
> has invalid maxpacket 512, setting to 64[101437.232210] usb 1-2: config 1
> interface 0 altsetting 0 endpoint 0x2 has invalid maxpacket 512, setting to
> 64*
> [101437.477816] usb 1-2: New USB device found, idVendor=<custom>,
> idProduct=<custom>, bcdDevice= 2.21
> [101437.477818] usb 1-2: New USB device strings: Mfr=1, Product=2,
> SerialNumber=0
> [101437.477820] usb 1-2: Product: my product name
> [101437.477821] usb 1-2: Manufacturer: my manufacturer
> [101437.702297] usb-storage 1-2:1.0: USB Mass Storage device detected
> [101437.713954] scsi host3: usb-storage 1-2:1.0
> [101438.976664] scsi 3:0:0:0: Direct-Access     Linux    UMS disk 0
> ffff PQ: 0 ANSI: 2
> [101438.979158] sd 3:0:0:0: Attached scsi generic sg2 type 0
> [101439.284100] sd 3:0:0:0: [sdb] 14876672 512-byte logical blocks: (7.62
> GB/7.09 GiB)
> [101439.468523] sd 3:0:0:0: [sdb] Write Protect is off
> [101439.468526] sd 3:0:0:0: [sdb] Mode Sense: 0f 00 00 00
> [101439.653020] sd 3:0:0:0: [sdb] Write cache: enabled, read cache:
> enabled, doesn't support DPO or FUA
> [101440.759756]  sdb: sdb1
> [101441.559083] sd 3:0:0:0: [sdb] Attached SCSI removable disk
>

Not that it sounds like it would interfere, but the USB from the SoC is
connected to an USB Hub (USB2514B), to which other devices are connected
and work correctly on both Windows and Linux.

Any ideas of what might be happening?


Cheers
Bruno


-- 
  Eng. Bruno Landau Albrecht
  e-mail: brunolalb at gmail.com