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 <peter.hutterer@who-t.net>
Tested-by: Wen He <wen.he_1@nxp.com>
Signed-off-by: Jiri Kosina <jkosina@suse.cz>

diff --git a/drivers/hid/hid-input.c b/drivers/hid/hid-input.c
index dea9cc65bf8007bc101c26b308c28e32b7714abb..c8633beae260ad87dee0f1be7b11c5fa90b1a9a6 100644 (file)
--- 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;
                }