linux-kernel - Re: [PATCH v5] psmouse - focaltech pass finger width to userspace

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Date:	Sun, 19 Apr 2015 18:13:15 +0300
From:	Dmitry Tunin <hanipouspilot@...il.com>
To:	linux-input@...r.kernel.org
CC:	Mathias Gottschlag <mgottschlag@...il.com>,
	linux-kernel@...r.kernel.org
Subject: Re: [PATCH v5] psmouse - focaltech pass finger width to userspace

> Focaltech touchpads report finger width in packet[5] of absolute packet.
> Range for width in raw format is 0x10 - 0x70. Second half-byte is always 0.
> 0xff is reported, when a large contact area is detected.
> This can be handled in userspace.
> 
> Signed-off-by: Dmitry Tunin <hanipouspilot@...il.com>
> ---
>  drivers/input/mouse/focaltech.c | 26 ++++++++++++++++++++++----
>  1 file changed, 22 insertions(+), 4 deletions(-)
> 
> diff --git a/drivers/input/mouse/focaltech.c b/drivers/input/mouse/focaltech.c
> index 23d2594..32f810c 100644
> --- a/drivers/input/mouse/focaltech.c
> +++ b/drivers/input/mouse/focaltech.c
> @@ -105,6 +105,16 @@ struct focaltech_hw_state {
>  
>  	/* True if the clickpad has been pressed. */
>  	bool pressed;
> +
> +	/*
> +	* Finger width 0-7 and 15 for 'latching'
> +	* 15 value stays until the finger is released
> +	* Width is reported only when 1 finger is active
> +	*/
> +	unsigned int width;
> +
> +	/* Finger count */
> +	unsigned int count;
>  };
>  
>  struct focaltech_data {
> @@ -137,10 +147,12 @@ static void focaltech_report_state(struct psmouse *psmouse)
>  			input_report_abs(dev, ABS_MT_POSITION_X, clamped_x);
>  			input_report_abs(dev, ABS_MT_POSITION_Y,
>  					 priv->y_max - clamped_y);
> +			if (state->count == 1)
> +				input_report_abs(dev, ABS_TOOL_WIDTH, state->width);
>  		}
>  	}
> -	input_mt_report_pointer_emulation(dev, true);
> -
> +	input_mt_report_finger_count(dev, state->count);	
> +	input_mt_report_pointer_emulation(dev, false);
>  	input_report_key(psmouse->dev, BTN_LEFT, state->pressed);
>  	input_sync(psmouse->dev);
>  }
> @@ -152,13 +164,16 @@ static void focaltech_process_touch_packet(struct psmouse *psmouse,
>  	struct focaltech_hw_state *state = &priv->state;
>  	unsigned char fingers = packet[1];
>  	int i;
> +	int count = 0;
>  
>  	state->pressed = (packet[0] >> 4) & 1;
>  
>  	/* the second byte contains a bitmap of all fingers touching the pad */
>  	for (i = 0; i < FOC_MAX_FINGERS; i++) {
> -		state->fingers[i].active = fingers & 0x1;
> -		if (!state->fingers[i].active) {
> +		if (fingers & 0x1) {
> +			state->fingers[i].active = true;
> +			count++;
> +		} else {
>  			/*
>  			 * Even when the finger becomes active again, we still
>  			 * will have to wait for the first valid position.
> @@ -167,6 +182,7 @@ static void focaltech_process_touch_packet(struct psmouse *psmouse,
>  		}
>  		fingers >>= 1;
>  	}
> +	state->count = count;
>  }
>  
>  static void focaltech_process_abs_packet(struct psmouse *psmouse,
> @@ -187,6 +203,7 @@ static void focaltech_process_abs_packet(struct psmouse *psmouse,
>  
>  	state->fingers[finger].x = ((packet[1] & 0xf) << 8) | packet[2];
>  	state->fingers[finger].y = (packet[3] << 8) | packet[4];
> +	state->width = packet[5] >> 4;
>  	state->fingers[finger].valid = true;
>  }
>  
> @@ -331,6 +348,7 @@ static void focaltech_set_input_params(struct psmouse *psmouse)
>  	__set_bit(EV_ABS, dev->evbit);
>  	input_set_abs_params(dev, ABS_MT_POSITION_X, 0, priv->x_max, 0, 0);
>  	input_set_abs_params(dev, ABS_MT_POSITION_Y, 0, priv->y_max, 0, 0);
> +	input_set_abs_params(dev, ABS_TOOL_WIDTH, 0, 15, 0, 0);
>  	input_mt_init_slots(dev, 5, INPUT_MT_POINTER);
>  	__set_bit(INPUT_PROP_BUTTONPAD, dev->propbit);
>  }
> 

This appear to work very will with xorg-synaptics. 
Since touchpad does not report pressure and synaptics require both
pressure and width to detect palm, it is needed to set pressure to minimum value:
synclient PalmMinZ=1
Then it works great. Last Mathias's commit removed palm detection from the kernel driver.
With this patch users can toggle it as they like.
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