Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754523AbdHVBN4 (ORCPT ); Mon, 21 Aug 2017 21:13:56 -0400 Received: from mail-pf0-f169.google.com ([209.85.192.169]:35556 "EHLO mail-pf0-f169.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754466AbdHVBNy (ORCPT ); Mon, 21 Aug 2017 21:13:54 -0400 From: Nicolas Boichat To: linux-input@vger.kernel.org Cc: Jiri Kosina , Benjamin Tissoires , linux-kernel@vger.kernel.org, dtor@chromium.org Subject: [PATCH] HID: hid-multitouch: forward MSC_TIMESTAMP Date: Tue, 22 Aug 2017 09:10:11 +0800 Message-Id: <20170822011011.39112-1-drinkcat@chromium.org> X-Mailer: git-send-email 2.14.1.480.gb18f417b89-goog Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 4612 Lines: 132 Computes and forwards the device timestamp according to the specification. Many devices use a 16-bit timestamp field, with a resolution of 100us, therefore rolling around very frequently (every 6.5 seconds). To make sure there is no ambiguity, the timestamp reported to the input stack reset to 0 whenever the time between 2 received events is greater than MAX_TIMESTAMP_INTERVAL (1 second). Signed-off-by: Nicolas Boichat --- Inspired from Benjamin Tissoires's patch here: https://patchwork.kernel.org/patch/1742181/, and changing the logic to resynchronize the timestamps to use received time instead of a potentially more fragile difference between the 2 deltas. drivers/hid/hid-multitouch.c | 42 ++++++++++++++++++++++++++++++++++++++++++ include/linux/hid.h | 1 + 2 files changed, 43 insertions(+) diff --git a/drivers/hid/hid-multitouch.c b/drivers/hid/hid-multitouch.c index 440b999304a5..996bdc9bf0e5 100644 --- a/drivers/hid/hid-multitouch.c +++ b/drivers/hid/hid-multitouch.c @@ -43,6 +43,7 @@ #include #include #include +#include #include #include @@ -136,6 +137,9 @@ struct mt_device { bool serial_maybe; /* need to check for serial protocol */ bool curvalid; /* is the current contact valid? */ unsigned mt_flags; /* flags to pass to input-mt */ + __s32 dev_time; /* the scan time provided by the device */ + unsigned long jiffies; /* the frame's jiffies */ + int timestamp; /* the timestamp to be sent */ }; static void mt_post_parse_default_settings(struct mt_device *td); @@ -177,6 +181,12 @@ static void mt_post_parse(struct mt_device *td); #define MT_DEFAULT_MAXCONTACT 10 #define MT_MAX_MAXCONTACT 250 +/* + * Resync device and local timestamps after that many microseconds without + * receiving data. + */ +#define MAX_TIMESTAMP_INTERVAL 1000000 + #define MT_USB_DEVICE(v, p) HID_DEVICE(BUS_USB, HID_GROUP_MULTITOUCH, v, p) #define MT_BT_DEVICE(v, p) HID_DEVICE(BUS_BLUETOOTH, HID_GROUP_MULTITOUCH, v, p) @@ -583,6 +593,12 @@ static int mt_touch_input_mapping(struct hid_device *hdev, struct hid_input *hi, cls->sn_pressure); mt_store_field(usage, td, hi); return 1; + case HID_DG_SCANTIME: + hid_map_usage(hi, usage, bit, max, + EV_MSC, MSC_TIMESTAMP); + input_set_capability(hi->input, EV_MSC, MSC_TIMESTAMP); + mt_store_field(usage, td, hi); + return 1; case HID_DG_CONTACTCOUNT: /* Ignore if indexes are out of bounds. */ if (field->index >= field->report->maxfield || @@ -718,6 +734,7 @@ static void mt_complete_slot(struct mt_device *td, struct input_dev *input) static void mt_sync_frame(struct mt_device *td, struct input_dev *input) { input_mt_sync_frame(input); + input_event(input, EV_MSC, MSC_TIMESTAMP, td->timestamp); input_sync(input); td->num_received = 0; if (test_bit(MT_IO_FLAGS_ACTIVE_SLOTS, &td->mt_io_flags)) @@ -727,6 +744,28 @@ static void mt_sync_frame(struct mt_device *td, struct input_dev *input) clear_bit(MT_IO_FLAGS_ACTIVE_SLOTS, &td->mt_io_flags); } +static int mt_compute_timestamp(struct mt_device *td, struct hid_field *field, + __s32 value) +{ + long delta = value - td->dev_time; + unsigned long jdelta = jiffies_to_usecs(jiffies - td->jiffies); + + td->jiffies = jiffies; + td->dev_time = value; + + if (delta < 0) + delta += field->logical_maximum; + + /* HID_DG_SCANTIME is expressed in 100us, we want it in us. */ + delta *= 100; + + if (jdelta > MAX_TIMESTAMP_INTERVAL) + /* No data received for a while, resync the timestamp. */ + return 0; + else + return td->timestamp + delta; +} + static int mt_touch_event(struct hid_device *hid, struct hid_field *field, struct hid_usage *usage, __s32 value) { @@ -787,6 +826,9 @@ static void mt_process_mt_event(struct hid_device *hid, struct hid_field *field, case HID_DG_HEIGHT: td->curdata.h = value; break; + case HID_DG_SCANTIME: + td->timestamp = mt_compute_timestamp(td, field, value); + break; case HID_DG_CONTACTCOUNT: break; case HID_DG_TOUCH: diff --git a/include/linux/hid.h b/include/linux/hid.h index ab05a86269dc..47dd962d9a7a 100644 --- a/include/linux/hid.h +++ b/include/linux/hid.h @@ -289,6 +289,7 @@ struct hid_item { #define HID_DG_DEVICEINDEX 0x000d0053 #define HID_DG_CONTACTCOUNT 0x000d0054 #define HID_DG_CONTACTMAX 0x000d0055 +#define HID_DG_SCANTIME 0x000d0056 #define HID_DG_BUTTONTYPE 0x000d0059 #define HID_DG_BARRELSWITCH2 0x000d005a #define HID_DG_TOOLSERIALNUMBER 0x000d005b -- 2.14.1.480.gb18f417b89-goog