On Tue, 29 Jun 2010, Alan Ott wrote: > > i am trying to send a vendor specific HID report from a userspace host > > program to vendor usb hid device > > using HIDRAW interface . > > > > > > but when i send report in the format< "Report ID "(0th byte )> > > <Report ID (1st byte )> < "data payload"> > > i am getting perfect report response from usb device . > > where we use usb_control_msg as : > > > > ret = usb_control_msg(dev, usb_sndctrlpipe(dev, 0), > > HID_REQ_SET_REPORT, > > USB_DIR_OUT | USB_TYPE_CLASS | USB_RECIP_INTERFACE, > > cpu_to_le16(((HID_OUTPUT_REPORT + 1)<< 8) | *buf), > > interface->desc.bInterfaceNumber, buf + 1, count - 1, > > USB_CTRL_SET_TIMEOUT); > > > > > > I thought I'd be able to just go check the HID specification and be able to > say that the report number is not sent as part of the payload for Set_Report > devices, since it would be redundant because the Report ID is sent over in the > wValue field. > > Unfortunately, I was not able to see that clearly laid out in the HID > specification in the section on Set_Report. I did however find language saying > "if a Report ID tag was used in the Report descriptor, all reports include a > single byte ID prefix," in section 8.1, Report Types. > > I did some tests with the Windows implementation, and indeed, when numbered > reports are used in the HID descriptor, the Windows implementation will send > the report ID as the first byte of the payload. > > Based on the language in the HID spec, and the behavior of Windows, I believe > the buf+1, count-1 to be a bug. > > Jiri, what do you think? Can you confirm? Correct, it is a bug indeed. Does any of you guys already have a patch handy which I could apply? Otherwise I'll fix it myself. Thanks for spotting it, -- Jiri Kosina SUSE Labs, Novell Inc. -- To unsubscribe from this list: send the line "unsubscribe linux-usb" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
