[Qemu-devel] Usb mouse fix

[Qemu-devel] Usb mouse fix

[Daniel Godás]

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Hi,

i think ive found a little bug on the usb mouse emulation (only with the
mouse, not the tablet), the wheel doesnt seem to work (it just doesnt do
anything). Ive tracked the problem down to usb-hid.c:

static const uint8_t qemu_mouse_hid_report_descriptor[] = {

    0x05, 0x01, 0x09, 0x02, 0xA1, 0x01, 0x09, 0x01,
    0xA1, 0x00, 0x05, 0x09, 0x19, 0x01, 0x29, 0x03,
    0x15, 0x00, 0x25, 0x01, 0x95, 0x03, 0x75, 0x01,
    0x81, 0x02, 0x95, 0x01, 0x75, 0x05, 0x81, 0x01,
    0x05, 0x01, 0x09, 0x30, 0x09, 0x31, 0x15, 0x81,
    0x25, 0x7F, 0x75, 0x08, 0x95, 0x02, 0x81, 0x06,
    0xC0, 0xC0,
};

That descriptor doesnt contain a 'wheel' section so when the virtualized OS
gives me the TD it only has space for dx and dy and not for the wheel delta
(its got a maximum length of 3). To fix the problem i just modified the
descriptor, here is the new one:

static const uint8_t qemu_mouse_hid_report_descriptor[] = {

    0x05, 0x01, 0x09, 0x02, 0xA1, 0x01, 0x09, 0x01,
    0xA1, 0x00, 0x05, 0x09, 0x19, 0x01, 0x29, 0x03,
    0x15, 0x00, 0x25, 0x01, 0x95, 0x03, 0x75, 0x01,
    0x81, 0x02, 0x95, 0x01, 0x75, 0x05, 0x81, 0x01,
    0x05, 0x01, 0x09, 0x30, 0x09, 0x31, 0x15, 0x81,
    0x25, 0x7F, 0x75, 0x08, 0x95, 0x02, 0x81, 0x06,
    0x05, 0x01, 0x09, 0x38, 0x15, 0x81, 0x25, 0x7F,
    0x35, 0x00, 0x45, 0x00, 0x75, 0x08, 0x95, 0x01,
    0x81, 0x02, 0xC0, 0xC0,
};

Now the virtualized OS gives me a TD with a maximum length of 4 and the
wheel works just fine.

Cheers,
Daniel

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