linux-kernel - Re: [PATCH 1/2] hid-multitouch: add support for trackpads

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Message-ID: <20120116145304.GA9828@polaris.bitmath.org>
Date:	Mon, 16 Jan 2012 15:53:04 +0100
From:	"Henrik Rydberg" <rydberg@...omail.se>
To:	Benjamin Tissoires <benjamin.tissoires@...c.fr>
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,
	Benjamin Tissoires <benjamin.tissoires@...il.com>
Subject: Re: [PATCH 1/2] hid-multitouch: add support for trackpads

Hi Benjamin,

> * some multitouch trackpads present the touch usage. This needs to be
> filtered as it will conflict with mt-implementation.
> * trackpads send BTN_TOOL_* to notify how many fingers are present
> (this is used by xorg to use synaptics instead of generic evdev)
> * trackpads like Perixx 701 are not different from a hid point of view
> from a touchscreen, and we need to manually set them as touchpad.

Missing subject line?

> @@ -265,17 +266,31 @@ static int mt_input_mapping(struct hid_device *hdev, struct hid_input *hi,
>  {
>  	struct mt_device *td = hid_get_drvdata(hdev);
>  	struct mt_class *cls = &td->mtclass;
> +	int code;
>  
>  	/* Only map fields from TouchScreen or TouchPad collections.
>           * We need to ignore fields that belong to other collections
>           * such as Mouse that might have the same GenericDesktop usages. */
>  	if (field->application == HID_DG_TOUCHSCREEN)
>  		set_bit(INPUT_PROP_DIRECT, hi->input->propbit);
> -	else if (field->application == HID_DG_TOUCHPAD)
> -		set_bit(INPUT_PROP_POINTER, hi->input->propbit);
> -	else
> +	else if (field->application != HID_DG_TOUCHPAD)
>  		return 0;
>  
> +	/* In case of an indirect device (touchpad), we need to add
> +	 * specific BTN_TOOL_* to be handled by the synaptics xorg
> +	 * driver.
> +	 * We also consider that touchscreens providing buttons are touchpads.
> +	 */
> +	if (field->application == HID_DG_TOUCHPAD ||
> +	    (usage->hid & HID_USAGE_PAGE) == HID_UP_BUTTON ||
> +	    cls->is_indirect) {
> +		set_bit(INPUT_PROP_POINTER, hi->input->propbit);
> +		set_bit(BTN_TOOL_FINGER, hi->input->keybit);
> +		set_bit(BTN_TOOL_DOUBLETAP, hi->input->keybit);
> +		set_bit(BTN_TOOL_TRIPLETAP, hi->input->keybit);
> +		set_bit(BTN_TOOL_QUADTAP, hi->input->keybit);
> +	}
> +
>  	/* eGalax devices provide a Digitizer.Stylus input which overrides
>  	 * the correct Digitizers.Finger X/Y ranges.
>  	 * Let's just ignore this input. */
> @@ -389,9 +404,20 @@ static int mt_input_mapping(struct hid_device *hdev, struct hid_input *hi,
>  				td->last_field_index = field->index;
>  			return -1;
>  		}
> +		case HID_DG_TOUCH:
> +			/* Legacy devices use TIPSWITCH and not TOUCH.
> +			 * Let's just ignore this field. */
> +			return -1;
>  		/* let hid-input decide for the others */
>  		return 0;
>  
> +	case HID_UP_BUTTON:
> +		code = ((usage->hid - 1) & HID_USAGE);
> +		code += BTN_MOUSE;

Any reason not to write ((usage->hid - 1) & HID_USAGE) | BTN_MOUSE?

> +		hid_map_usage(hi, usage, bit, max, EV_KEY, code);
> +		input_set_capability(hi->input, EV_KEY, code);
> +		return 1;
> +
>  	case 0xff000000:
>  		/* we do not want to map these: no input-oriented meaning */
>  		return -1;
> @@ -453,6 +479,7 @@ static void mt_complete_slot(struct mt_device *td)
>  static void mt_emit_event(struct mt_device *td, struct input_dev *input)
>  {
>  	int i;
> +	int finger_count = 0;
>  
>  	for (i = 0; i < td->maxcontacts; ++i) {
>  		struct mt_slot *s = &(td->slots[i]);
> @@ -477,12 +504,14 @@ static void mt_emit_event(struct mt_device *td, struct input_dev *input)
>  			input_event(input, EV_ABS, ABS_MT_PRESSURE, s->p);
>  			input_event(input, EV_ABS, ABS_MT_TOUCH_MAJOR, major);
>  			input_event(input, EV_ABS, ABS_MT_TOUCH_MINOR, minor);
> +			finger_count++;
>  		}
>  		s->seen_in_this_frame = false;
>  
>  	}
>  
>  	input_mt_report_pointer_emulation(input, true);
> +	input_mt_report_finger_count(input, finger_count);
>  	input_sync(input);
>  	td->num_received = 0;
>  }
> @@ -538,6 +567,9 @@ static int mt_event(struct hid_device *hid, struct hid_field *field,
>  			if (value)
>  				td->num_expected = value;
>  			break;
> +		case HID_DG_TOUCH:
> +			/* do nothing */
> +			break;
>  
>  		default:
>  			/* fallback to the generic hidinput handling */
> -- 
> 1.7.4.4

Looks good otherwise.

Thanks,
Henrik
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