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

From: Nicolas Saenz Julienne
Date: Fri Jun 14 2019 - 08:33:25 EST

On Fri, 2019-06-14 at 10:52 +0200, Nicolas Saenz Julienne wrote:
> On Fri, 2019-06-14 at 09:02 +0900, Jean-Baptiste ThÃou 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 ThÃou <jb@xxxxxxxxxxxxx>
> > 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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