HID: wacom: Handle failing HID_DG_CONTACTMAX requests

Hardware may not respond to a request for the HID_DG_CONTACTMAX feature and
we should be tolerant of such a failure. This is especially true when using
hid-replay where the hardware doesn't exist, but also for devices attached
to a flaky bus. This patch increases the number of allowable retries to
match other calls to 'wacom_get_report' and also provides a fallback which
forces 'touch_max = 16' (enough for any Wacom device seen so far).

Signed-off-by: Jason Gerecke <jason.gerecke@wacom.com>
Reviewed-by: Benjamin Tissoires <benjamin.tissoires@redhat.com>
Signed-off-by: Jiri Kosina <jkosina@suse.cz>

diff --git a/drivers/hid/wacom_sys.c b/drivers/hid/wacom_sys.c
index 109312f9d3de082ffed0806b3a90a32a943bc6b1..eea18a6cbdc701490fb4908ff0740de61bd5c888 100644 (file)
--- a/drivers/hid/wacom_sys.c
+++ b/drivers/hid/wacom_sys.c
@@ -125,9 +125,16 @@ static void wacom_feature_mapping(struct hid_device *hdev,
                                break;
                        data[0] = field->report->id;
                        ret = wacom_get_report(hdev, HID_FEATURE_REPORT,
-                                               data, 2, 0);
-                       if (ret == 2)
+                                               data, 2, WAC_CMD_RETRIES);
+                       if (ret == 2) {
                                features->touch_max = data[1];
+                       } else {
+                               features->touch_max = 16;
+                               hid_warn(hdev, "wacom_feature_mapping: "
+                                        "could not get HID_DG_CONTACTMAX, "
+                                        "defaulting to %d\n",
+                                         features->touch_max);
+                       }
                        kfree(data);
                }
                break;