Re: [PATCH v2] psmouse - focaltech pass finger width to userspace

[Dmitry Tunin <hanipouspilot@gmail.com>]

18.04.2015 16:35, Dmitry Tunin пишет:
> 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@gmail.com>
> ---
>  drivers/input/mouse/focaltech.c | 9 +++++++++
>  1 file changed, 9 insertions(+)
> 
> diff --git a/drivers/input/mouse/focaltech.c b/drivers/input/mouse/focaltech.c
> index 23d2594..25e4bb3 100644
> --- a/drivers/input/mouse/focaltech.c
> +++ b/drivers/input/mouse/focaltech.c
> @@ -90,6 +90,12 @@ struct focaltech_finger_state {
>  	 */
>  	unsigned int x;
>  	unsigned int y;
> +
> +	/*
> +	* Finger width 0-7 and 15 for 'latching'
> +	* 15 value stays until the finger is released
> +	*/
> +	unsigned int width;
>  };
>  
>  /*
> @@ -137,6 +143,7 @@ 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);
> +			input_report_abs(dev, ABS_TOOL_WIDTH, finger->width);
>  		}
>  	}
>  	input_mt_report_pointer_emulation(dev, true);
> @@ -187,6 +194,7 @@ 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->fingers[finger].width = packet[5] >> 4;
>  	state->fingers[finger].valid = true;
>  }
>  
> @@ -331,6 +339,7 @@ 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);
>  }
> 
After some testing I discovered that this looking quite harmless patch leads to a regression.
At least on a weak laptop X200MA with xorg-synaptics.

If I scroll with two fingers and then lift them and put them down again, the scrolled text jerks further.
I think it is because of limited bandwidth of PS/2. When I increase amount of data, it starts behaving worse.
Relative packets do not report finger width either way, so we do not need to report it each time.
If general idea is approved, then it can be done another way, so finger width information is sent, when it is really
appropriate. 
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