[U-Boot] [PATCH] dfu, usb: set usb descriptor to values defined in dfu spec 1.1

[Heiko Schocher]

Hello Marek,

Am 05.09.2014 00:42, schrieb Marek Vasut:
> On Thursday, September 04, 2014 at 12:21:40 PM, Heiko Schocher wrote:
>
> Hi Heiko,
>
> I'll just rant a bit, but please wait until Lukasz does a proper runthrough.
>
>> set bDeviceClass, bDeviceSubClass and bcdUSB to the values
>> defined in dfu spec 1.1 chapter 4.2.1 found here:
>>
>> http://www.usb.org/developers/devclass_docs/DFU_1.1.pdf
>
> This URL gives me a website with:
> "
> Resource not found.
> Please check the URL and try again.
> "

:-( Maybe it is deleted currently there?
Hmm.. there is a search field if you open the above URL ... and if you type
DFU and press search, you get:

DFU
File Format: PDF/Adobe Acrobat
Aug 5, 2004 ... USB Device Firmware Upgrade Specification, Revision 1.1. 2. Intellectual Property Disclaimer. THIS SPECIFICATION IS PROVIDED “AS IS” ...
www.usb.org/developers/devclass_docs/DFU_1.1.pdf

This is exactly the above link ...

This link is also referenced from openmoko:

http://wiki.openmoko.org/wiki/USB_DFU_-_The_USB_Device_Firmware_Upgrade_standard

>> Signed-off-by: Heiko Schocher<hs at denx.de>
>> Cc: Lukasz Majewski<l.majewski at samsung.com>
>> Cc: Marek Vasut<marex at denx.de>
>> Cc: Roger Meier<r.meier at siemens.com>
>>
>> ---
>>
>> before this patch, "dfu-util -l" showed:
>>
>> Bus 002 Device 114: ID 0908:02c5 Siemens AG
>> Device Descriptor:
>>    bLength                18
>>    bDescriptorType         1
>>    bcdUSB               2.00
>>    bDeviceClass            2 Communications
>>    bDeviceSubClass         2 Abstract (modem)
>>    bDeviceProtocol         0 None
>>    bMaxPacketSize0        64
>>    idVendor           0x0908 Siemens AG
>>    idProduct          0x02c5
>>    bcdDevice            0.00
>>    iManufacturer           1 Siemens AG
>>
>> with this patch:
>>
>> Bus 002 Device 089: ID 0908:02c5 Siemens AG
>> Device Descriptor:
>>    bLength                18
>>    bDescriptorType         1
>>    bcdUSB               1.10
>>    bDeviceClass            0 (Defined at Interface level)
>>    bDeviceSubClass         0
>>    bDeviceProtocol         0
>>    bMaxPacketSize0        64
>>    idVendor           0x0908 Siemens AG
>>    idProduct          0x02c5
>>    bcdDevice            0.00
>>    iManufacturer           1 Siemens AG
>>    iProduct                2 USB download gadget
>>
>> which fits for "bcdUSB", "bDeviceClass" and "bDeviceSubClass" with
>> the DFU spezifikation.
>
> This patch doesn't seem fully right, let me explain below please.
>
>> ---
>>   drivers/usb/gadget/f_dfu.c | 5 +++--
>>   drivers/usb/gadget/g_dnl.c | 6 +++---
>>   2 files changed, 6 insertions(+), 5 deletions(-)
>>
>> diff --git a/drivers/usb/gadget/f_dfu.c b/drivers/usb/gadget/f_dfu.c
>> index 9128add..9429e50 100644
>> --- a/drivers/usb/gadget/f_dfu.c
>> +++ b/drivers/usb/gadget/f_dfu.c
>> @@ -83,8 +83,9 @@ static struct usb_descriptor_header *dfu_runtime_descs[]
>> = { static const struct usb_qualifier_descriptor dev_qualifier = {
>>   	.bLength =		sizeof dev_qualifier,
>>   	.bDescriptorType =	USB_DT_DEVICE_QUALIFIER,
>> -	.bcdUSB =		__constant_cpu_to_le16(0x0200),
>> -	.bDeviceClass =		USB_CLASS_VENDOR_SPEC,
>> +	.bcdUSB =		__constant_cpu_to_le16(0x0110),
>
> See [1] and look for first and second instance of 'bcdUsb' there please. Quote
> of the second one:
>
> '
> The bcdUSB field reports the highest version of USB the device supports. The
> value is in binary coded decimal with a format of 0xJJMN where JJ is the major
> version number, M is the minor version number and N is the sub minor version
> number. e.g. USB 2.0 is reported as 0x0200, USB 1.1 as 0x0110 and USB 1.0 as
> 0x0100.
> '
>
> So this should be configured dynamically based on what the highest mode the
> controller supports is, no?

Good question ... the DFU 1.1 spezification says in chapter
4.2.1 DFU Mode Device Descriptor:

bcdUSB = 0100  USB specification release number in binary coded decimal.
                (which seems wrong, as the spez is version 1.1, see [2])
bDeviceClass = 0
bDeviceSubClass = 0

... ?

I discussed this change with Lukasz, see:

[2] http://lists.denx.de/pipermail/u-boot/2014-August/186918.html

>
>> +	.bDeviceClass =		USB_CLASS_PER_INTERFACE,
>
> This might be OK.
>
>> +	.bDeviceSubClass =	0x00,
>
> But this is not, the device definitelly isn't CDC-serial.
>
> [...]
>
> [1] http://www.beyondlogic.org/usbnutshell/usb5.shtml

bye,
Heiko
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