On Sep 26 2016 or thereabouts, Ioan-Adrian Ratiu wrote:
> Commit 79346d620e9d ("HID: input: force generic axis to be mapped to their
> user space axis") made mapping generic axes to their userspace equivalents
> mandatory and some lower end gamepads which were depending on the previous
> behaviour suffered severe regressions because they were reusing axes and
> expecting hid-input to multiplex their map to the respective userspace axis
> by always searching for and using the next available axis.
Yes, I apologies for the breakage and the regression, though I must say
that for now, only one hardware maker and one device (or range of devices
from the look of it) has needed to be quirked.
>
> Now the result is that different device axes appear on a single axis in
> userspace, which is clearly a regression in the hid-input driver because it
> needs to continue to handle this hardware as expected before the forcing
> to provide the same interface to userspace.
>
> Since these lower-end gamepads like 0079:0006 are definitely the exception,
> create a quirk to fix them.
Given that we only have this particular vendor that is an issue, I'd
rather see the fix in hid-dr.c. The reason being that you actually don't
need to have a global quirk and this simplifies the path in hid-input.
Plus for users, they can just upgrade hid-dr without having to recompile
their kernel when hid-core is not compiled as a module.
The cleanest solution that wouldn't require any quirk in hid-core is to
simply add an .input_mapping() callback in hid-dr.c.
The code of the callback could be something like (untested):
static int dr_input_mapping(struct hid_device *hdev, struct hid_input *hi,
struct hid_field *field, struct hid_usage *usage,
unsigned long **bit, int *max)
{
switch (usage->hid) {
/*
* revert the old hid-input behavior where axes
* can be randomly assigned when the hid usage is
* reused.
*/
case HID_GD_X: case HID_GD_Y: case HID_GD_Z:
case HID_GD_RX: case HID_GD_RY: case HID_GD_RZ:
if (field->flags & HID_MAIN_ITEM_RELATIVE)
map_rel(usage->hid & 0xf);
else
map_abs(usage->hid & 0xf);
return 1;
}
return 0;
}
Hopefully, something like this should revert the old behavior for all
hid-dr touchpads.
Ideally, we need to have Dragon Rise 0x0011 tested too. Nick, would you
mind checking it if you still have this particular device?
Cheers,
Benjamin
>
> Signed-off-by: Ioan-Adrian Ratiu <[email protected]>
> ---
> drivers/hid/hid-dr.c | 2 ++
> drivers/hid/hid-input.c | 16 +++++++++++-----
> include/linux/hid.h | 1 +
> 3 files changed, 14 insertions(+), 5 deletions(-)
>
> diff --git a/drivers/hid/hid-dr.c b/drivers/hid/hid-dr.c
> index 2523f8a..27fc826 100644
> --- a/drivers/hid/hid-dr.c
> +++ b/drivers/hid/hid-dr.c
> @@ -274,6 +274,8 @@ static int dr_probe(struct hid_device *hdev, const struct
> hid_device_id *id)
> hid_hw_stop(hdev);
> goto err;
> }
> + /* has only 5 axes and reuses X, Y */
> + hdev->quirks |= HID_QUIRK_REUSE_AXES;
> break;
> }
>
> diff --git a/drivers/hid/hid-input.c b/drivers/hid/hid-input.c
> index fb9ace1..1cc6fe4 100644
> --- a/drivers/hid/hid-input.c
> +++ b/drivers/hid/hid-input.c
> @@ -633,11 +633,17 @@ static void hidinput_configure_usage(struct hid_input
> *hidinput, struct hid_fiel
> /* These usage IDs map directly to the usage codes. */
> case HID_GD_X: case HID_GD_Y: case HID_GD_Z:
> case HID_GD_RX: case HID_GD_RY: case HID_GD_RZ:
> - if (field->flags & HID_MAIN_ITEM_RELATIVE)
> - map_rel(usage->hid & 0xf);
> - else
> - map_abs_clear(usage->hid & 0xf);
> - break;
> +
> + /* if quirk is active don't force the userspace mapping,
> + * instead search and use the next available axis.
> + */
> + if (!(device->quirks & HID_QUIRK_REUSE_AXES)) {
> + if (field->flags & HID_MAIN_ITEM_RELATIVE)
> + map_rel(usage->hid & 0xf);
> + else
> + map_abs_clear(usage->hid & 0xf);
> + break;
> + }
>
> case HID_GD_SLIDER: case HID_GD_DIAL: case HID_GD_WHEEL:
> if (field->flags & HID_MAIN_ITEM_RELATIVE)
> diff --git a/include/linux/hid.h b/include/linux/hid.h
> index 75b66ec..0979920 100644
> --- a/include/linux/hid.h
> +++ b/include/linux/hid.h
> @@ -320,6 +320,7 @@ struct hid_item {
> #define HID_QUIRK_NO_EMPTY_INPUT 0x00000100
> #define HID_QUIRK_NO_INIT_INPUT_REPORTS 0x00000200
> #define HID_QUIRK_ALWAYS_POLL 0x00000400
> +#define HID_QUIRK_REUSE_AXES 0x00000800
> #define HID_QUIRK_SKIP_OUTPUT_REPORTS 0x00010000
> #define HID_QUIRK_SKIP_OUTPUT_REPORT_ID 0x00020000
> #define HID_QUIRK_NO_OUTPUT_REPORTS_ON_INTR_EP 0x00040000
> --
> 2.10.0
>
