HID: input: do not run GET_REPORT unless there's a Resolution Multiplier (1ad273d6) · Commits · 戴 / test

hid-multitouch currently runs GET_REPORT for Contact Max and again to retrieve the Win8 blob. If both are within the same report, the Resolution Multiplier code calls GET_FEATURE again and this time, possibly due to timing, it causes the ILITEK-TP device interpret the GET_FEATURE as an instruction to change the mode and effectively stop the device from functioning as expected. Notably: the device doesn't even have a Resolution Multiplier so it shouldn't be affected by any of this at all. Fix this by making sure we only execute GET_REPORT if there is a Resolution Multiplier in the respective report. Where the HID_QUIRK_NO_INIT_REPORTS field is set we just bail out immediately. This shouldn't be triggered by any real device anyway. Signed-off-by:

Peter Hutterer <peter.hutterer@who-t.net> Tested-by:

Wen He <wen.he_1@nxp.com> Signed-off-by:

Jiri Kosina <jkosina@suse.cz>

drivers/hid/hid-input.c

+20 −10

Original line number	Diff line number	Diff line
		@@ -1560,21 +1560,12 @@ static bool __hidinput_change_resolution_multipliers(struct hid_device *hid,
		{
		struct hid_usage *usage;
		bool update_needed = false;
		bool get_report_completed = false;
		int i, j;

		if (report->maxfield == 0)
		return false;

		/*
		* If we have more than one feature within this report we
		* need to fill in the bits from the others before we can
		* overwrite the ones for the Resolution Multiplier.
		*/
		if (report->maxfield > 1) {
		hid_hw_request(hid, report, HID_REQ_GET_REPORT);
		hid_hw_wait(hid);
		}

		for (i = 0; i < report->maxfield; i++) {
		__s32 value = use_logical_max ?
		report->field[i]->logical_maximum :
		@@ -1593,6 +1584,25 @@ static bool __hidinput_change_resolution_multipliers(struct hid_device *hid,
		if (usage->hid != HID_GD_RESOLUTION_MULTIPLIER)
		continue;

		/*
		* If we have more than one feature within this
		* report we need to fill in the bits from the
		* others before we can overwrite the ones for the
		* Resolution Multiplier.
		*
		* But if we're not allowed to read from the device,
		* we just bail. Such a device should not exist
		* anyway.
		*/
		if (!get_report_completed && report->maxfield > 1) {
		if (hid->quirks & HID_QUIRK_NO_INIT_REPORTS)
		return update_needed;

		hid_hw_request(hid, report, HID_REQ_GET_REPORT);
		hid_hw_wait(hid);
		get_report_completed = true;
		}

		report->field[i]->value[j] = value;
		update_needed = true;
		}

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