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Commit 2c1d8aea authored by Jiri Kosina's avatar Jiri Kosina
Browse files

HID: handle cases of volume knobs generating relative values 



There are some devices (for example Dell Multimedia Keyboard SK-8135) that have
a volume control knob which generates relative events instead of absolute.
hid-input maps them to ABS_VOLUME. HUT pages don't restrict volume to absolute
values.

Adding REL_VOLUME doesn't seem feasible, nothing knows how to handle it. This
patch translates relative ABS_VOLUME events into appropriate number of series
of VOLUME_UP or VOLUME_DOWN events respectively, so that userspace sees the
correct values in the end.

kernel.org bugzilla 5233

Reported-by: default avatarJochen Eisinger <jochen@penguin-breeder.org>
Signed-off-by: default avatarJiri Kosina <jkosina@suse.cz>
parent 3c5f4b25

drivers/hid/hid-input.c

+25 −0
Original line number Diff line number Diff line
@@ -882,6 +882,16 @@ static void hidinput_configure_usage(struct hid_input *hidinput, struct hid_fiel 
			field->dpad = usage->code;

	}



	/* for those devices which produce Consumer volume usage as relative,

	 * we emulate pressing volumeup/volumedown appropriate number of times

	 * in hidinput_hid_event()

	 */

	if ((usage->type == EV_ABS) && (field->flags & HID_MAIN_ITEM_RELATIVE) &&

			(usage->code == ABS_VOLUME)) {

		set_bit(KEY_VOLUMEUP, input->keybit);

		set_bit(KEY_VOLUMEDOWN, input->keybit);

	}



	hid_resolv_event(usage->type, usage->code);

#ifdef CONFIG_HID_DEBUG

	printk("\n");
@@ -972,6 +982,21 @@ void hidinput_hid_event(struct hid_device *hid, struct hid_field *field, struct 
	if ((usage->type == EV_KEY) && (usage->code == 0)) /* Key 0 is "unassigned", not KEY_UNKNOWN */

		return;



	if ((usage->type == EV_ABS) && (field->flags & HID_MAIN_ITEM_RELATIVE) &&

			(usage->code == ABS_VOLUME)) {

		int count = abs(value);

		int direction = value > 0 ? KEY_VOLUMEUP : KEY_VOLUMEDOWN;

		int i;



		for (i = 0; i < count; i++) {

			input_event(input, EV_KEY, direction, 1);

			input_sync(input);

			input_event(input, EV_KEY, direction, 0);

			input_sync(input);

		}

		return;

	}



	input_event(input, usage->type, usage->code, value);



	if ((field->flags & HID_MAIN_ITEM_RELATIVE) && (usage->type == EV_KEY))