RE: [linux-usb-devel] hid and low-speed devices

[John Homppi]

Hi Sergey,
This failure mode also occurs with the ADU200 device from Ontrak Control 
Systems.
The ADU200 is a HID device with no bulk endpoints; only control and 
interrupt endpoints.

As you pointed out,  hid-core.c assumes that all HID devices have a 
bulk-out endpoint.
Thus the ADU200 appears in the hid_blacklist in hid-core.c

If someone knowledgeable made the change to hid-core.c then I would be willing
to test it. I suspect that the change may not be simple as there may be 
repercussions in
other areas of the Linux kernel.

I already have code that attempts to use the ADU200 as a HID device (of 
course it
fails so I have been using my own driver instead.)

Bye,
John Homppi
Sergey Vlasov wrote:
----------
From:   Sergey Vlasov
Sent:   Sunday, December 14, 2003 11:14 AM
To:     Johann Deneux
Cc:     [EMAIL PROTECTED]
Subject:        Re: [linux-usb-devel] hid and low-speed devices
<<<original message from Johann Deneux snipped>>>

Seems that the real problem is in hid-core.c:

                endpoint = &interface->endpoint[n].desc;
                if ((endpoint->bmAttributes & 3) != 3)          /* Not an 
interrupt endpoint */
                        continue;

                if (endpoint->bEndpointAddress & USB_DIR_IN) {
                        if (hid->urbin)
                                continue;
                        if (!(hid->urbin = usb_alloc_urb(0, GFP_KERNEL)))
                                goto fail;
                        pipe = usb_rcvintpipe(dev, 
endpoint->bEndpointAddress);
                        usb_fill_int_urb(hid->urbin, dev, pipe, 
hid->inbuf, 0,
                                        hid_irq_in, hid, 
endpoint->bInterval);
                        hid->urbin->transfer_dma = hid->inbuf_dma;
                        hid->urbin->transfer_flags |= 
URB_NO_TRANSFER_DMA_MAP;
                } else {
                        if (hid->urbout)
                                continue;
                        if (!(hid->urbout = usb_alloc_urb(0, GFP_KERNEL)))
                                goto fail;
                        pipe = usb_sndbulkpipe(dev, 
endpoint->bEndpointAddress);
                        usb_fill_bulk_urb(hid->urbout, dev, pipe, 
hid->outbuf, 0,
                                          hid_irq_out, hid);
                        hid->urbout->transfer_dma = hid->outbuf_dma;
                        hid->urbout->transfer_flags |= 
URB_NO_TRANSFER_DMA_MAP;
                }

Notice that for the input endpoint it correctly uses usb_rcvintpipe()
and usb_fill_int_urb(), but for the output endpoint usb_sndbulkpipe()
and usb_fill_bulk_urb() are used (even though it is really an
interrupt endpoint).  How could this work?
So it is the HID core which must be fixed.  Unfortunately, I don't
have any HID device which would have an interrupt out endpoint...


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