Re: Hi all, I'm newbe, so apologize for my stupid questions.

Alle 22:28, sabato 22 settembre 2007, Alan Stern ha scritto:
> On Sat, 22 Sep 2007, Fabio Giovagnini wrote:
> > Thanks i advance.
> >
> > Found the problem, but not the solution.
> > I'm using suse linux 10.2 with kernel 2.6.16.8-05-default;
> > I added a printk line into:
> > drivers/usb/host/uhci-q.c
> > into the finction:
> > uhci_result_common
> > at line 943
> > refers below for chunck of code.
> > I got:
> > len=8;explen=64
> > in such condition is proper the HCD behaviour;
> > But why I have 64 expected and 8 actual?
>
> Because the kernel doesn't know the maxpacket size for endpoint 0,
> since it hasn't yet seen the Device Descriptor.  It guesses 64, but on
> your device the size is 8.  So the driver thinks your device has sent a
> short packet and it ends the data stage of the transfer.  It goes
> directly to the status stage without trying to read the other 10 bytes.
>
> Your device must be able to handle this.

RE: Sorry Alan, how my device can handle this?
my Device Controller has to be configured with 8 bytes FIFO length and 8 bytes 
of max packet length for endpoint 0 biung the control endpoint.
I cannot specify during endpoint configuration the endpoint 0 has to be 
cconfigured with max packet lentgh of 64 bytes.
Should I intercept the final status stage interrupt ad trasmit in it the other 
bytes?

Thanks.


>
> > Is expected len a property the uhci set by the kernel, or something
> > read form the device?
>
> It is the packet size the driver expects to receive.
>
> > len is the actual len received by the endpoint, or the field
> > bMaxPacketSize0 of Standard Device Descriptor (USB Spec Rev 2.0; pag.
> > 263; Table 9.8 cont.), or it is the max packet length set when you
> > configure the endpoint?
>
> It is the actual length received from the device.
>
> Alan Stern

-- 
Fabio Giovagnini

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