Hi Alan 2017-09-21 0:50 GMT+09:00 Alan Stern <stern@xxxxxxxxxxxxxxxxxxx>: > On Wed, 20 Sep 2017, Kim Jaejoong wrote: > >> To. usb & input guys. >> >> While dig this report, i was wondering about bNumDescriptors in HID descriptor. >> HID document from usb.org said, 'this number must be at least one (1) >> as a Report descriptor will always be present.' >> >> There is no mention of the order of class descriptors. Suppose you >> have a HID device with a report descriptor and a physical descriptor. >> >> If you have the following hid descriptor in this case, >> HID descriptor >> bLength: 12 >> bDescriptor Type: HID >> .. skip >> bNumDescriptors: 2 >> bDescriptorType: physical >> bDescriptorLength: any >> bDescriptorType: Report >> bDescriptorLength: any >> >> If the order of the report descriptor is the second as above, >> usbhid_parse () will fail because my patch is only check the first >> bDescriptor Type. >> But If the order of the report descriptor is always first, there is no >> problem. How do you think this? > > The descriptors can appear in any order. You should not assume that > the report descriptor will always come first. Thanks for clarifying. I will resend patch with modification. Jaejoong > > Alan Stern > -- To unsubscribe from this list: send the line "unsubscribe linux-input" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
