Attaching the dump files... Regards, Aniruddha On Thu, Apr 9, 2009 at 8:59 PM, Aniruddha Marathe <marathe.aniruddha@xxxxxxxxx> wrote: > Hi All, > > I am trying to understand how usb.c, the only working user mode driver > example that I found on the net that uses gadgetfs. Using that code as > the base I am trying to write a HID keyboard driver (user mode) with > Net2280 peripheral device controller to simulate working of a > keyboard. I referred to the following discussion that happened almost > half a decade ago but didn't lead to any useful conclusions (but did > help me find answers to some of my questions): > > http://www.mail-archive.com/linux-usb-devel@xxxxxxxxxxxxxxxxxxxxx/msg20380.html > > I am running Wireshark with USB support on the host to see what's > going on. I've attached the traces of real keyboard and my simulation > keyboard with this email. Based on that I have the following (newbie) > questions: > > 1. After the response to 'GET DEVICE DESCRIPTOR' request, the trace of > simulation driver shows that the host sends a 'GET DESCRIPTOR DEVICE > QUALIFIER' request. I do not see such request in the trace for the > real keyboard. What is the meaning of this request? Was the response > to the earlier 'GET DEVICE DESCRIPTOR' request malformed (the sniffer > doesn't indicate that, however)? > > Simulation keyboard trace: > > -------------------------------------------------------------------------------------------------- > Source Destination Protocol Info > -------------------------------------------------------------------------------------------------- > host 23.0 USB GET DESCRIPTOR Request > DEVICE QUALIFIER > > > 2. My simulation keyboard driver stops responding after the following request: > > ------------------------------------------------------------------------------- > Source Destination Protocol Info > ------------------------------------------------------------------------------- > host 3.0 USB SET CONFIGURATION Request > > What should my driver send as a response back to the host? I saw that > the real keyboard just sends a response with 0's filled in it. Is this > what it is supposed to send? Keyboard simulator creates a new thread > for 'ep-a' management and writes the endpoint descriptor into ep-a's > file descriptor. But the host doesn't seem to get it (can't see it > on Wireshark). What I see is a (probable) timeout after 5 sec and 0's > filled in 'SET CONFIGURATION' response. Also after this, the host > doesn't send a request for reports, like it does in case of the real > keyboard. Why does this happen? > > > 3. The real keyboard has an IN endpoint of type interrupt. As far as I > understand, this is the endpoint that should be sending the report > descriptors to the host. However, in Wireshark I see that when the > host sends a 'GET DESCRIPTOR RPIPE' request the ep0 of the real > keyboard sends the report instead of ep1. Here is the trace (I assume > '3.0' means ep0): > > ------------------------------------------------------------------------------------- > Source Destination Protocol Info > ------------------------------------------------------------------------------------- > host 3.0 USB GET DESCRIPTOR Request RPIPE > > Since ep1 is interrupt type, shouldn't it send the report when the > host sends an 'IN' token packet to ep0 instead of ep0 sending it when > the host sends 'GET DESCRIPTOR RPIPE' to ep0? > > 4. Is there any other documentation available on gadgetfs and usb.c > apart from the source code itself? > > Thanking you in advance. > > Regards, > Aniruddha >
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kbd1.dump
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mykbd1.dump
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