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Date:	Mon, 28 Jan 2013 16:01:29 +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 02/25] HID: multitouch: add support for Nexio 42" panel

Hi Benjamin,

> This device is the worst device I saw. It keeps TipSwitch and InRange
> at 1 for fingers that are not touching the panel.
> The solution is to rely on the field ContactCount, which is accurate
> as the correct information are packed at the begining of the frame.
> 
> Unfortunately, CountactCount is most of the time at the end of the report.
> The solution is to pick it when we have the whole report in raw_event.
> 
> Signed-off-by: Benjamin Tissoires <benjamin.tissoires@...il.com>
> ---
>  drivers/hid/hid-ids.h        |  3 ++
>  drivers/hid/hid-multitouch.c | 91 ++++++++++++++++++++++++++++++++++++--------
>  2 files changed, 78 insertions(+), 16 deletions(-)

I think it would make more sense to introduce a method where the
driver sees all report values at once. We have had reasonable cause to
add it in the past, but never did.

> 
> diff --git a/drivers/hid/hid-ids.h b/drivers/hid/hid-ids.h
> index dad56aa..0935012 100644
> --- a/drivers/hid/hid-ids.h
> +++ b/drivers/hid/hid-ids.h
> @@ -597,6 +597,9 @@
>  #define USB_VENDOR_ID_NEC		0x073e
>  #define USB_DEVICE_ID_NEC_USB_GAME_PAD	0x0301
>  
> +#define USB_VENDOR_ID_NEXIO		0x1870
> +#define USB_DEVICE_ID_NEXIO_MULTITOUCH_420	0x010d
> +
>  #define USB_VENDOR_ID_NEXTWINDOW	0x1926
>  #define USB_DEVICE_ID_NEXTWINDOW_TOUCHSCREEN	0x0003
>  
> diff --git a/drivers/hid/hid-multitouch.c b/drivers/hid/hid-multitouch.c
> index 46d8136..c4acdd0 100644
> --- a/drivers/hid/hid-multitouch.c
> +++ b/drivers/hid/hid-multitouch.c
> @@ -32,6 +32,8 @@
>  #include <linux/slab.h>
>  #include <linux/usb.h>
>  #include <linux/input/mt.h>
> +#include <asm/unaligned.h>
> +#include <asm/byteorder.h>
>  #include "usbhid/usbhid.h"
>  
>  
> @@ -54,6 +56,7 @@ MODULE_LICENSE("GPL");
>  #define MT_QUIRK_NO_AREA		(1 << 9)
>  #define MT_QUIRK_IGNORE_DUPLICATES	(1 << 10)
>  #define MT_QUIRK_HOVERING		(1 << 11)
> +#define MT_QUIRK_CONTACT_CNT_ACCURATE	(1 << 12)
>  
>  struct mt_slot {
>  	__s32 x, y, cx, cy, p, w, h;
> @@ -83,6 +86,10 @@ struct mt_device {
>  	struct mt_class mtclass;	/* our mt device class */
>  	struct mt_fields *fields;	/* temporary placeholder for storing the
>  					   multitouch fields */
> +	struct hid_field *contactcount;	/* the hid_field contact count that
> +					   will be picked in mt_raw_event */
> +	__s8 contactcount_index;	/* the index of the usage contact count
> +					   in its hid_field. */
>  	unsigned last_field_index;	/* last field index of the report */
>  	unsigned last_slot_field;	/* the last field of a slot */
>  	__s8 inputmode;		/* InputMode HID feature, -1 if non-existent */
> @@ -111,6 +118,7 @@ struct mt_device {
>  #define MT_CLS_DUAL_INRANGE_CONTACTNUMBER	0x0007
>  #define MT_CLS_DUAL_NSMU_CONTACTID		0x0008
>  #define MT_CLS_INRANGE_CONTACTNUMBER		0x0009
> +#define MT_CLS_ALWAYS_TRUE			0x000a
>  
>  /* vendor specific classes */
>  #define MT_CLS_3M				0x0101
> @@ -170,6 +178,9 @@ static struct mt_class mt_classes[] = {
>  	{ .name = MT_CLS_INRANGE_CONTACTNUMBER,
>  		.quirks = MT_QUIRK_VALID_IS_INRANGE |
>  			MT_QUIRK_SLOT_IS_CONTACTNUMBER },
> +	{ .name = MT_CLS_ALWAYS_TRUE,
> +		.quirks = MT_QUIRK_ALWAYS_VALID |
> +			MT_QUIRK_CONTACT_CNT_ACCURATE },
>  
>  	/*
>  	 * vendor specific classes
> @@ -250,6 +261,9 @@ static ssize_t mt_set_quirks(struct device *dev,
>  
>  	td->mtclass.quirks = val;
>  
> +	if (!td->contactcount)
> +		td->mtclass.quirks &= ~MT_QUIRK_CONTACT_CNT_ACCURATE;
> +
>  	return count;
>  }
>  
> @@ -264,24 +278,26 @@ static struct attribute_group mt_attribute_group = {
>  	.attrs = sysfs_attrs
>  };
>  
> +static int mt_find_usage_index(struct hid_field *field, struct hid_usage *usage)
> +{
> +	int i;
> +	for (i = 0; i < field->maxusage; i++) {
> +		if (field->usage[i].hid == usage->hid)
> +			return i;
> +	}
> +	return -1;
> +}
> +
>  static void mt_feature_mapping(struct hid_device *hdev,
>  		struct hid_field *field, struct hid_usage *usage)
>  {
>  	struct mt_device *td = hid_get_drvdata(hdev);
> -	int i;
>  
>  	switch (usage->hid) {
>  	case HID_DG_INPUTMODE:
>  		td->inputmode = field->report->id;
> -		td->inputmode_index = 0; /* has to be updated below */
> -
> -		for (i=0; i < field->maxusage; i++) {
> -			if (field->usage[i].hid == usage->hid) {
> -				td->inputmode_index = i;
> -				break;
> -			}
> -		}
> -
> +		td->inputmode_index = mt_find_usage_index(field, usage);
> +		/* inputmode_index can't be set at -1 */
>  		break;
>  	case HID_DG_CONTACTMAX:
>  		td->maxcontact_report_id = field->report->id;
> @@ -459,6 +475,10 @@ static int mt_input_mapping(struct hid_device *hdev, struct hid_input *hi,
>  			td->last_field_index = field->index;
>  			return 1;
>  		case HID_DG_CONTACTCOUNT:
> +			td->contactcount = field;
> +			td->contactcount_index = mt_find_usage_index(field,
> +									usage);
> +			/* contactcount_index can't be set at -1 */
>  			td->last_field_index = field->index;
>  			return 1;
>  		case HID_DG_CONTACTMAX:
> @@ -523,6 +543,10 @@ static int mt_compute_slot(struct mt_device *td, struct input_dev *input)
>   */
>  static void mt_complete_slot(struct mt_device *td, struct input_dev *input)
>  {
> +	if ((td->mtclass.quirks & MT_QUIRK_CONTACT_CNT_ACCURATE) &&
> +	    td->num_received >= td->num_expected)
> +		return;
> +
>  	if (td->curvalid || (td->mtclass.quirks & MT_QUIRK_ALWAYS_VALID)) {
>  		int slotnum = mt_compute_slot(td, input);
>  		struct mt_slot *s = &td->curdata;
> @@ -623,12 +647,6 @@ static int mt_event(struct hid_device *hid, struct hid_field *field,
>  			td->curdata.h = value;
>  			break;
>  		case HID_DG_CONTACTCOUNT:
> -			/*
> -			 * Includes multi-packet support where subsequent
> -			 * packets are sent with zero contactcount.
> -			 */
> -			if (value)
> -				td->num_expected = value;
>  			break;
>  		case HID_DG_TOUCH:
>  			/* do nothing */
> @@ -658,6 +676,37 @@ static int mt_event(struct hid_device *hid, struct hid_field *field,
>  	return 1;
>  }
>  
> +static int mt_raw_event(struct hid_device *hid, struct hid_report *report,
> +			u8 *data, int size)
> +{
> +	struct mt_device *td = hid_get_drvdata(hid);
> +	struct hid_field *field = td->contactcount;
> +	s32 *value;
> +
> +	if (field && report->id == field->report->id) {
> +		/*
> +		 * Pick in advance the field HID_DG_CONTACTCOUNT as it is
> +		 * often placed at the end of the report.
> +		 */
> +		if (report->id)
> +			data++;
> +
> +		value = hid_extract_field(hid, field, data);
> +		if (!value)
> +			return 0;
> +
> +		/*
> +		 * Includes multi-packet support where subsequent
> +		 * packets are sent with zero contactcount.
> +		 */
> +		if (value[td->contactcount_index])
> +			td->num_expected = value[td->contactcount_index];
> +
> +		kfree(value);
> +	}
> +	return 0;
> +}

This is a lot of cycles for something that is already available in the core.

> +
>  static void mt_set_input_mode(struct hid_device *hdev)
>  {
>  	struct mt_device *td = hid_get_drvdata(hdev);
> @@ -719,11 +768,15 @@ static void mt_post_parse_default_settings(struct mt_device *td)
>  static void mt_post_parse(struct mt_device *td)
>  {
>  	struct mt_fields *f = td->fields;
> +	struct mt_class *cls = &td->mtclass;
>  
>  	if (td->touches_by_report > 0) {
>  		int field_count_per_touch = f->length / td->touches_by_report;
>  		td->last_slot_field = f->usages[field_count_per_touch - 1];
>  	}
> +
> +	if (!td->contactcount)
> +		cls->quirks &= ~MT_QUIRK_CONTACT_CNT_ACCURATE;
>  }
>  
>  static void mt_input_configured(struct hid_device *hdev, struct hid_input *hi)
> @@ -1056,6 +1109,11 @@ static const struct hid_device_id mt_devices[] = {
>  		MT_USB_DEVICE(USB_VENDOR_ID_TURBOX,
>  			USB_DEVICE_ID_TURBOX_TOUCHSCREEN_MOSART) },
>  
> +	/* Nexio panels */
> +	{ .driver_data = MT_CLS_ALWAYS_TRUE,
> +		MT_USB_DEVICE(USB_VENDOR_ID_NEXIO,
> +			USB_DEVICE_ID_NEXIO_MULTITOUCH_420)},
> +
>  	/* Panasonic panels */
>  	{ .driver_data = MT_CLS_PANASONIC,
>  		MT_USB_DEVICE(USB_VENDOR_ID_PANASONIC,
> @@ -1193,6 +1251,7 @@ static struct hid_driver mt_driver = {
>  	.feature_mapping = mt_feature_mapping,
>  	.usage_table = mt_grabbed_usages,
>  	.event = mt_event,
> +	.raw_event = mt_raw_event,

Rather a new and simpler event method here, in other words.

>  #ifdef CONFIG_PM
>  	.reset_resume = mt_reset_resume,
>  	.resume = mt_resume,
> -- 
> 1.8.1
> 

Thanks,
Henrik
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