Commit e1594409 authored Sep 27, 2016 by Ioan-Adrian Ratiu Committed by Jiri Kosina Oct 10, 2016

HID: hid-dr: add input mapping for axis selection

Commit 79346d62 ("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.

One solution is to add a hid quirk for this type of "previous" behaviour in
hid-input to bypass the new axes policy in favour of the old one, but since
only one hardware vendor seems to be affected negatively we're better off
making and exception and mapping in the driver for now; if more vendors or
drivers turn out to experience the problem we should reconsider the quirk
solution.

Signed-off-by: Ioan-Adrian Ratiu <adi@adirat.com>
Reviewed-by: Benjamin Tissoires <benjamin.tissoires@redhat.com>
Signed-off-by: Jiri Kosina <jkosina@suse.cz>

parent 3d1355b3

drivers/hid/hid-dr.c

+25 −0

Original line number	Diff line number	Diff line
		@@ -306,6 +306,30 @@ static __u8 dr_report_fixup(struct hid_device hdev, __u8 *rdesc,
		return rdesc;
		}

		#define map_abs(c) hid_map_usage(hi, usage, bit, max, EV_ABS, (c))
		#define map_rel(c) hid_map_usage(hi, usage, bit, max, EV_REL, (c))

		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 to the old hid-input behavior where axes
		* can be randomly assigned when 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;
		}

		static int dr_probe(struct hid_device hdev, const struct hid_device_id id)
		{
		int ret;
		@@ -352,6 +376,7 @@ static struct hid_driver dr_driver = {
		.id_table = dr_devices,
		.report_fixup = dr_report_fixup,
		.probe = dr_probe,
		.input_mapping = dr_input_mapping,
		};
		module_hid_driver(dr_driver);

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