[U-Boot] dfu: some wrong usb_qualifier_descriptor settings?

[Lukasz Majewski]

Hi Heiko,

> Hello Lukasz,
> 
> In the dfu spez [1] chapter 4.2.1 the following fields are specified:
> 
> bDeviceClass = 00h (Description: „see interface“), currently set in
> U-Boot to 2.
> 
> bDeviceSubClass = 00h (Description: „see interface“), currently set in
> U-Boot to 2.
> 
> bcdUSB = xxxxh (Description: USB specification release number in
> binary coded decimal -> 0110h) Currently set to 0x200
> 
> If I look in ./drivers/usb/gadget/f_dfu.c:
> 
> 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,
>          .bNumConfigurations =   1,
> };
> 
> bDeviceClass = USB_CLASS_VENDOR_SPEC = 0xff ?
> 
>    Hmm... why states the doc this should be set to 0 =
> USB_CLASS_PER_INTERFACE? 2 is USB_CLASS_COMM ... which seems more
> appropriate ...

The bDeviceClass seems to be set to wrong value. I think that it should
have values as they are specified by the standard.

> 
> bDeviceSubClass is not defined ...
> bcdUSB = 0x0200 which should be 0x0110 ... oh, as [1] is the dfu 1.1
> specification it should be 0x0110 but the spec [1] says 0100 ... is
> the spec here buggy? is there a dfu 2.0 specification availiable?

The 2.0 value is a reminiscent of the original DFU code (once prepared
for Linux) and was wrongly set to indicate USB 2.0. 

I think that we should have 0x0110, which indicates supported DFU
version 1.1.

> 
> Has this differences to the spec some reason? Or can we change them
> to the values specified in the spec?

I think that values which you have pointed out are wrong and should be
changed to the one from spec.

> 
> Thanks!
> 
> bye,
> Heiko
> 
> [1]: http://www.usb.org/developers/devclass_docs/DFU_1.1.pdf



-- 
Best regards,

Lukasz Majewski

Samsung R&D Institute Poland (SRPOL) | Linux Platform Group