Re: Trust WB-5400 webcam

At 01:22 PM 7/10/2007, Rial Juan wrote:

>Bus 007 Device 003: ID 0c45:624e Microdia
>Device Descriptor:
>   bLength                18
>   bDescriptorType         1
>   bcdUSB               2.00
>   bDeviceClass            0 (Defined at Interface level)
>   bDeviceSubClass         0
>   bDeviceProtocol         0
>   bMaxPacketSize0        64
>   idVendor           0x0c45 Microdia
>   idProduct          0x624e
>

snip

>     Interface Descriptor:
>       bLength                 9
>       bDescriptorType         4
>       bInterfaceNumber        0
>       bAlternateSetting       8
>       bNumEndpoints           3
>       bInterfaceClass       255 Vendor Specific Class
>       bInterfaceSubClass    255 Vendor Specific Subclass
>       bInterfaceProtocol    255 Vendor Specific Protocol
>       iInterface              0
>       Endpoint Descriptor:
>         bLength                 7
>         bDescriptorType         5
>         bEndpointAddress     0x81  EP 1 IN
>         bmAttributes            1
>           Transfer Type            Isochronous
>           Synch Type               None
>           Usage Type               Data
>         wMaxPacketSize     0x1400  3x 0 bytes
>         bInterval               1

I don't know who the maintainer for lsusb is, but the above ep 
descriptor decode is kind of confusing. I am testing high speed, high 
bandwidth iso/in endpoints (from a FX2 device side) and noticed this 
in my 2.6.20.15 ubuntu system. The problem would seem to be that 
lsusb is using the usb 1.1 max packet size of 1023 (0x3ff) as a mask 
for the endpoint size. Really it should use 0x7ff as a mask as 
described in the usb 2.0 doc, then it will work clearly for both usb 
1.0 and 2.0. If it did that it would show:

         wMaxPacketSize     0x1400  3x 1024 bytes

Regards, Steve


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