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Message-ID: <20121113172711.GA856@polaris.bitmath.org>
Date: Tue, 13 Nov 2012 18:27:11 +0100
From: "Henrik Rydberg" <rydberg@...omail.se>
To: Benjamin Tissoires <benjamin.tissoires@...il.com>
Cc: Dmitry Torokhov <dmitry.torokhov@...il.com>,
Jiri Kosina <jkosina@...e.cz>,
Stephane Chatty <chatty@...c.fr>, linux-input@...r.kernel.org,
linux-kernel@...r.kernel.org
Subject: Re: [PATCH v3 13/13] HID: hid-multitouch: forwards ABS_SCAN_TIME
Hi Benjamin,
> From: Benjamin Tissoires <benjamin.tissoires@...il.com>
> Date: Tue, 13 Nov 2012 15:12:17 +0100
> Subject: [PATCH v4] HID: hid-multitouch: forwards MSC_TIMESTAMP
>
> Computes the device timestamp according to the specification.
> It also ensures that if the time between two events is greater
> than MAX_TIMESTAMP_INTERVAL, the timestamp will be reset.
>
> Signed-off-by: Benjamin Tissoires <benjamin.tissoires@...il.com>
> ---
> drivers/hid/hid-multitouch.c | 46 +++++++++++++++++++++++++++++++++++++++++---
> include/linux/hid.h | 1 +
> 2 files changed, 44 insertions(+), 3 deletions(-)
>
> diff --git a/drivers/hid/hid-multitouch.c b/drivers/hid/hid-multitouch.c
> index caf0f0b..3f8432d 100644
> --- a/drivers/hid/hid-multitouch.c
> +++ b/drivers/hid/hid-multitouch.c
> @@ -32,6 +32,7 @@
> #include <linux/slab.h>
> #include <linux/usb.h>
> #include <linux/input/mt.h>
> +#include <linux/jiffies.h>
Why?
> #include "usbhid/usbhid.h"
>
>
> @@ -98,6 +99,9 @@ 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 */
> + unsigned timestamp; /* the timestamp to be sent */
Why not just dev_time here?
> };
>
> /* classes of device behavior */
> @@ -126,6 +130,8 @@ struct mt_device {
> #define MT_DEFAULT_MAXCONTACT 10
> #define MT_MAX_MAXCONTACT 250
>
> +#define MAX_TIMESTAMP_INTERVAL 500000
> +
Needs to be done in userland anyways, so no need to check this in the kernel.
> #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)
>
> @@ -451,12 +457,19 @@ static int mt_input_mapping(struct hid_device *hdev, struct hid_input *hi,
> mt_store_field(usage, td, hi);
> td->last_field_index = field->index;
> return 1;
> + case HID_DG_SCANTIME:
> + hid_map_usage(hi, usage, bit, max,
> + EV_MSC, MSC_TIMESTAMP);
> + set_bit(MSC_TIMESTAMP, hi->input->mscbit);
> + td->last_field_index = field->index;
> + return 1;
> case HID_DG_CONTACTCOUNT:
> td->last_field_index = field->index;
> return 1;
> case HID_DG_CONTACTMAX:
> - /* we don't set td->last_slot_field as contactcount and
> - * contact max are global to the report */
> + /* we don't set td->last_slot_field as scan time,
> + * contactcount and contact max are global to the
> + * report */
> td->last_field_index = field->index;
> return -1;
> }
> @@ -485,7 +498,8 @@ static int mt_input_mapped(struct hid_device *hdev, struct hid_input *hi,
> struct hid_field *field, struct hid_usage *usage,
> unsigned long **bit, int *max)
> {
> - if (usage->type == EV_KEY || usage->type == EV_ABS)
> + if (usage->type == EV_KEY || usage->type == EV_ABS ||
> + usage->type == EV_MSC)
> set_bit(usage->type, hi->input->evbit);
>
> return -1;
> @@ -565,11 +579,34 @@ 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_event(input, EV_MSC, MSC_TIMESTAMP, td->timestamp);
I think this should go after the frame sync,
> input_mt_sync_frame(input);
And the computation (100 * td->dev_time) should work fine. It will wrap
properly.
> input_sync(input);
> td->num_received = 0;
> }
>
> +static void 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 ms. */
> + delta *= 100;
> +
> + if (abs(delta - jdelta) > MAX_TIMESTAMP_INTERVAL)
> + /* obviously wrong clock -> the device time has been reset */
> + td->timestamp = 0;
> + else
> + td->timestamp += delta;
> +}
> +
Can be skipped entirely.
> static int mt_event(struct hid_device *hid, struct hid_field *field,
> struct hid_usage *usage, __s32 value)
> {
> @@ -617,6 +654,9 @@ static int mt_event(struct hid_device *hid, struct hid_field *field,
> case HID_DG_HEIGHT:
> td->curdata.h = value;
> break;
> + case HID_DG_SCANTIME:
> + mt_compute_timestamp(td, field, value);
Just td->dev_time = value should work fine here.
> + break;
> case HID_DG_CONTACTCOUNT:
> /*
> * Includes multi-packet support where subsequent
> diff --git a/include/linux/hid.h b/include/linux/hid.h
> index 6b4f322..0337e50 100644
> --- a/include/linux/hid.h
> +++ b/include/linux/hid.h
> @@ -279,6 +279,7 @@ struct hid_item {
> #define HID_DG_DEVICEINDEX 0x000d0053
> #define HID_DG_CONTACTCOUNT 0x000d0054
> #define HID_DG_CONTACTMAX 0x000d0055
> +#define HID_DG_SCANTIME 0x000d0056
Was this missing this the old patch, or did it get moved here?
>
> /*
> * HID report types --- Ouch! HID spec says 1 2 3!
> --
> 1.8.0
Thanks,
Henrik
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