Re: [Libusb-devel] USB bus reset

[Ahmed A. <ahm...@gm...>]

Sorry , Your sequence is exactly right except that the repetition happens
due to the wrong size of Packet size I set -I guess-

Now I fixed it but I get the dmesg output :

*config 1 has 0 interface different from the descriptor value : 1
*
On 28 February 2012 17:25, Alan Stern <st...@ro...> wrote:

> On Tue, 28 Feb 2012, Ahmed Abdelfattah wrote:
>
> > Hello ,
> >
> > I have a ques not related to libusb but to USB generally .
> >
> > I have an ISP1362 usb chip on a development kit , I modified its firmware
> > to act as as HID and I added some printfs to debug the code .
> > During the enumeration this happens :
> >
> > 1 - the host issues a getdescriptor request
> > 2- the device sends the descriptor
> > 3 - the host sets the address of the device
> > 4 - the host does a bus reset
> > 5 - the host issues a getdescriptor request
> > 6 - the device writes the descriptor to the endpoint buffer
> > *7 - the host does a bus reset and then repeat from 1 to 7 infinitely
> >
> > Anyone knows what could the problem be ?*
>
> That sequence of events is very unlikely.  You probably are missing
> something.  Furthermore, the repeats you see in step 7 are not normal;
> they are the result of errors in your device.
>
> Under Linux (and under Windows too, I believe) the actual sequence of
> events is this:
>
> 1: The host does a bus reset
> 2: The host sends a Get-Device-Descriptor request
> 3: The device sends the descriptor
> 4: The host does another bus reset
> 5: The host sends a Set-Address request
> 6: The host sends a Get-Device-Descriptor request
> and so on...
>
> Notice there are no bus resets after the Set-Address.
>
> By the way, timing is not very critical.  The device is allowed up to 5
> seconds to respond to the Get-Descriptor and Set-Address requests.
>
>
> > Thank you  ,
> >
> > I removed all printfs and tried to connect it again but to linux to see
> the
> > output of dmesg and it behaves exactly the same I said before it loops
> > infintely but it only loops for 4 times on windows or linux .
> >
> > dmesg output :
> >
> >
> >    1. [  229.190020] usb 6-1: new full speed USB device using uhci_hcd
> and
> >    address 6
> >    2. [  229.339036] usb 6-1: device descriptor read/all, error -75
>
> This indicates that your device is not sending its device descriptor
> correctly.  Error -75 is -EOVERFLOW, which means the device sent a
> packet that was too large.
>
> What is your device's bMaxPacketSize0?
>
> Alan Stern
>
>


-- 
regards ,
Ahmed Abdelfattah