Re: Regression post "HID: core: move Usage Page concatenation to Main item"

[Nicolas Saenz Julienne <nsaenzjulienne@suse.de>]

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On Fri, 2019-06-14 at 10:52 +0200, Nicolas Saenz Julienne wrote:
> On Fri, 2019-06-14 at 09:02 +0900, Jean-Baptiste Théou wrote:
> > Sorry - Please find the public link:
> > 
> > 
> 
https://android.googlesource.com/platform/cts/+/master/tests/tests/hardware/res/raw/asus_gamepad_register.json
> > Best regards
> > 
> > On Fri, Jun 14, 2019 at 9:01 AM Jean-Baptiste Théou <jb@essential.com>
> > wrote:
> > > Hi,
> > > 
> > > This patch (58e75155009cc800005629955d3482f36a1e0eec) is triggering a
> > > regression with the following descriptor (report not working as
> > > expected)
> > > 
> > > 
> 
https://partner-android.googlesource.com/platform/cts/+/refs/heads/q-fs-release/tests/tests/hardware/res/raw/asus_gamepad_register.json
> > > Didn't see anything obviously wrong with this gamepad descriptor, so
> > > not sure what's trigger the regression.
> > > 
> > > Thanks a lot
> > > 
> > > Best regards
> 
> Added Benjamin to the mail thread.
> 
> For the record here's the report descritor, I have the feeling the issue is
> related to the Usage Page being defined in the middle of the Usage
> ennumeration.
> 
> 0x05, 0x01,         /*  Usage Page (Desktop),               */
> 0x09, 0x05,         /*  Usage (Gamepad),                    */
> 0xA1, 0x01,         /*  Collection (Application),           */
> 0x85, 0x01,         /*      Report ID (1),                  */
> 0x05, 0x09,         /*      Usage Page (Button),            */
> 0x0A, 0x01, 0x00,   /*      Usage (01h),                    */
> 0x0A, 0x02, 0x00,   /*      Usage (02h),                    */
> 0x0A, 0x04, 0x00,   /*      Usage (04h),                    */
> 0x0A, 0x05, 0x00,   /*      Usage (05h),                    */
> 0x0A, 0x07, 0x00,   /*      Usage (07h),                    */
> 0x0A, 0x08, 0x00,   /*      Usage (08h),                    */
> 0x0A, 0x0E, 0x00,   /*      Usage (0Eh),                    */
> 0x0A, 0x0F, 0x00,   /*      Usage (0Fh),                    */
> 0x0A, 0x0D, 0x00,   /*      Usage (0Dh),                    */
> 0x05, 0x0C,         /*      Usage Page (Consumer),          */
> 0x0A, 0x24, 0x02,   /*      Usage (AC Back),                */
> 0x0A, 0x23, 0x02,   /*      Usage (AC Home),                */
> 0x15, 0x00,         /*      Logical Minimum (0),            */
> 0x25, 0x01,         /*      Logical Maximum (1),            */
> 0x75, 0x01,         /*      Report Size (1),                */
> 0x95, 0x0B,         /*      Report Count (11),              */
> 0x81, 0x02,         /*      Input (Variable),               */
> 0x75, 0x01,         /*      Report Size (1),                */
> 0x95, 0x01,         /*      Report Count (1),               */
> 0x81, 0x03,         /*      Input (Constant, Variable),     */
> 0x05, 0x01,         /*      Usage Page (Desktop),           */
> 0x75, 0x04,         /*      Report Size (4),                */
> 0x95, 0x01,         /*      Report Count (1),               */
> 0x25, 0x07,         /*      Logical Maximum (7),            */
> 0x46, 0x3B, 0x01,   /*      Physical Maximum (315),         */
> 0x66, 0x14, 0x00,   /*      Unit (Degrees),                 */
> 0x09, 0x39,         /*      Usage (Hat Switch),             */
> 0x81, 0x42,         /*      Input (Variable, Null State),   */
> 0x66, 0x00, 0x00,   /*      Unit,                           */
> 0x09, 0x01,         /*      Usage (Pointer),                */
> 0xA1, 0x00,         /*      Collection (Physical),          */
> 0x09, 0x30,         /*          Usage (X),                  */
> 0x09, 0x31,         /*          Usage (Y),                  */
> 0x09, 0x32,         /*          Usage (Z),                  */
> 0x09, 0x35,         /*          Usage (Rz),                 */
> 0x05, 0x02,         /*          Usage Page (Simulation),    */
> 0x09, 0xC5,         /*          Usage (C5h),                */
> 0x09, 0xC4,         /*          Usage (C4h),                */
> 0x15, 0x00,         /*          Logical Minimum (0),        */
> 0x26, 0xFF, 0x00,   /*          Logical Maximum (255),      */
> 0x35, 0x00,         /*          Physical Minimum (0),       */
> 0x46, 0xFF, 0x00,   /*          Physical Maximum (255),     */
> 0x75, 0x08,         /*          Report Size (8),            */
> 0x95, 0x06,         /*          Report Count (6),           */
> 0x81, 0x02,         /*          Input (Variable),           */

Well as it was stated in 57e75155009 ("HID: core: move Usage Page concatenation
to Main item"):

The spec is not pretty clear as 5.2.2.7 states "Any usage that follows
is interpreted as a Usage ID and concatenated with the Usage Page".
While 5.2.2.8 states "When the parser encounters a main item it
concatenates the last declared Usage Page with a Usage to form a
complete usage value." Being somewhat contradictory it was decided to
match Window's implementation, which follows 5.2.2.8.

This breaks the Report above as X, Y, Z and Rz will be concatenanted with the
'Simulation' Usage Page as opposed to the 'Desktop' one.

Based on the USB IDs can't find much information on this Gamepad, is it a real
one? If so I guess the solution would be to fix the report descriptor in a
custom driver. Otherwise I'd suggest fixing the descriptors directly on the
test suite.

Regards,
Nicolas

> 0xC0,               /*      End Collection,                 */
> 0x85, 0x02,         /*      Report ID (2),                  */
> 0x05, 0x08,         /*      Usage Page (LED),               */
> 0x0A, 0x01, 0x00,   /*      Usage (01h),                    */
> 0x0A, 0x02, 0x00,   /*      Usage (02h),                    */
> 0x0A, 0x03, 0x00,   /*      Usage (03h),                    */
> 0x0A, 0x04, 0x00,   /*      Usage (04h),                    */
> 0x15, 0x00,         /*      Logical Minimum (0),            */
> 0x25, 0x01,         /*      Logical Maximum (1),            */
> 0x75, 0x01,         /*      Report Size (1),                */
> 0x95, 0x04,         /*      Report Count (4),               */
> 0x91, 0x02,         /*      Output (Variable),              */
> 0x75, 0x04,         /*      Report Size (4),                */
> 0x95, 0x01,         /*      Report Count (1),               */
> 0x91, 0x03,         /*      Output (Constant, Variable),    */
> 0xC0,               /*  End Collection,                     */
> 0x05, 0x0C,         /*  Usage Page (Consumer),              */
> 0x09, 0x01,         /*  Usage (Consumer Control),           */
> 0xA1, 0x01,         /*  Collection (Application),           */
> 0x85, 0x03,         /*      Report ID (3),                  */
> 0x05, 0x01,         /*      Usage Page (Desktop),           */
> 0x09, 0x06,         /*      Usage (Keyboard),               */
> 0xA1, 0x02,         /*      Collection (Logical),           */
> 0x05, 0x06,         /*          Usage Page (Device),        */
> 0x09, 0x20,         /*          Usage (20h),                */
> 0x15, 0x00,         /*          Logical Minimum (0),        */
> 0x26, 0xFF, 0x00,   /*          Logical Maximum (255),      */
> 0x75, 0x08,         /*          Report Size (8),            */
> 0x95, 0x01,         /*          Report Count (1),           */
> 0x81, 0x02,         /*          Input (Variable),           */
> 0x06, 0xBC, 0xFF,   /*          Usage Page (FFBCh),         */
> 0x0A, 0xAD, 0xBD,   /*          Usage (BDADh),              */
> 0x75, 0x08,         /*          Report Size (8),            */
> 0x95, 0x06,         /*          Report Count (6),           */
> 0x81, 0x02,         /*          Input (Variable),           */
> 0xC0,               /*      End Collection,                 */
> 0xC0                /*  End Collection                      */
> 


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