From 1ad273d6ff2d3af6ce3a4c8bd81a2ba10151ae0e Mon Sep 17 00:00:00 2001 From: Peter Hutterer Date: Tue, 9 Jun 2020 16:03:19 +1000 Subject: [PATCH] HID: input: do not run GET_REPORT unless there's a Resolution Multiplier 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 Tested-by: Wen He Signed-off-by: Jiri Kosina --- drivers/hid/hid-input.c | 30 ++++++++++++++++++++---------- 1 file changed, 20 insertions(+), 10 deletions(-) diff --git a/drivers/hid/hid-input.c b/drivers/hid/hid-input.c index dea9cc6..c8633be 100644 --- a/drivers/hid/hid-input.c +++ b/drivers/hid/hid-input.c @@ -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; } -- 2.7.4