Re: [PATCH 2/3] Input: synaptics - add multitouch multifinger support

[Chris Bagwell <chris@cnpbagwell.com>]

On 10/08/2010 09:57 AM, Chase Douglas wrote:
> Newer multitouch Synaptics trackpads do not advertise multifinger
> support. Now that we have multitouch support, we can use the number of
> touches to report multifinger functionality.
>
> In conjunction with the X synaptics input module, this enables
> functionality such as two finger scrolling.
>
> Signed-off-by: Chase Douglas<chase.douglas@canonical.com>
> ---
>   drivers/input/mouse/synaptics.c |   24 +++++++++++++-----------
>   drivers/input/mouse/synaptics.h |    1 +
>   2 files changed, 14 insertions(+), 11 deletions(-)
>
> diff --git a/drivers/input/mouse/synaptics.c b/drivers/input/mouse/synaptics.c
> index 990598f..7289d88 100644
> --- a/drivers/input/mouse/synaptics.c
> +++ b/drivers/input/mouse/synaptics.c
> @@ -471,7 +471,6 @@ static void synaptics_process_packet(struct psmouse *psmouse)
>   	struct input_dev *dev = psmouse->dev;
>   	struct synaptics_data *priv = psmouse->private;
>   	struct synaptics_hw_state hw;
> -	int num_fingers;
>   	int finger_width;
>   	int i;
>
> @@ -483,6 +482,7 @@ static void synaptics_process_packet(struct psmouse *psmouse)
>   			input_report_abs(dev, ABS_MT_POSITION_Y,
>   					 YMAX_NOMINAL + YMIN_NOMINAL - hw.y);
>   			input_report_abs(dev, ABS_MT_PRESSURE, hw.z);
> +			priv->num_fingers++;
>   		}
>
>   		input_mt_sync(dev);
> @@ -510,13 +510,13 @@ static void synaptics_process_packet(struct psmouse *psmouse)
>   	}
>
>   	if (hw.z>  0) {
> -		num_fingers = 1;
> +		priv->num_fingers++;

In this area of code, its not as obvious your relying on MT packets to 
always come before standard packets.  I think its worth a comment here 
or below on why your initialising priv->num_fingers at bottom of 
processing instead of at top of processing.

It will also help explain to reader why mt_sync events work out as expected.

>   		finger_width = 5;
>   		if (SYN_CAP_EXTENDED(priv->capabilities)) {
>   			switch (hw.w) {
>   			case 0 ... 1:
>   				if (SYN_CAP_MULTIFINGER(priv->capabilities))
> -					num_fingers = hw.w + 2;
> +					priv->num_fingers = hw.w + 2;
>   				break;
>   			case 2:
>   				if (SYN_MODEL_PEN(priv->model_id))
> @@ -528,10 +528,8 @@ static void synaptics_process_packet(struct psmouse *psmouse)
>   				break;
>   			}
>   		}
> -	} else {
> -		num_fingers = 0;
> +	} else
>   		finger_width = 0;
> -	}
>
>   	/* Post events
>   	 * BTN_TOUCH has to be first as mousedev relies on it when doing
> @@ -555,15 +553,19 @@ static void synaptics_process_packet(struct psmouse *psmouse)
>   	if (SYN_CAP_PALMDETECT(priv->capabilities))
>   		input_report_abs(dev, ABS_TOOL_WIDTH, finger_width);
>
> -	input_report_key(dev, BTN_TOOL_FINGER, num_fingers == 1);
> +	input_report_key(dev, BTN_TOOL_FINGER, priv->num_fingers == 1);
>   	input_report_key(dev, BTN_LEFT, hw.left);
>   	input_report_key(dev, BTN_RIGHT, hw.right);
>
> -	if (SYN_CAP_MULTIFINGER(priv->capabilities)) {
> -		input_report_key(dev, BTN_TOOL_DOUBLETAP, num_fingers == 2);
> -		input_report_key(dev, BTN_TOOL_TRIPLETAP, num_fingers == 3);
> +	if (SYN_CAP_MULTIFINGER(priv->capabilities) || priv->multitouch) {
> +		input_report_key(dev, BTN_TOOL_DOUBLETAP,
> +				 priv->num_fingers == 2);
> +		input_report_key(dev, BTN_TOOL_TRIPLETAP,
> +				 priv->num_fingers == 3);
>   	}
>
> +	priv->num_fingers = 0;
> +
>   	if (SYN_CAP_MIDDLE_BUTTON(priv->capabilities))
>   		input_report_key(dev, BTN_MIDDLE, hw.middle);
>
> @@ -674,7 +676,7 @@ static void set_input_params(struct input_dev *dev, struct synaptics_data *priv)
>   	__set_bit(BTN_LEFT, dev->keybit);
>   	__set_bit(BTN_RIGHT, dev->keybit);
>
> -	if (SYN_CAP_MULTIFINGER(priv->capabilities)) {
> +	if (SYN_CAP_MULTIFINGER(priv->capabilities) || priv->multitouch) {
>   		__set_bit(BTN_TOOL_DOUBLETAP, dev->keybit);
>   		__set_bit(BTN_TOOL_TRIPLETAP, dev->keybit);
>   	}
> diff --git a/drivers/input/mouse/synaptics.h b/drivers/input/mouse/synaptics.h
> index 5126c9c..0989b8d 100644
> --- a/drivers/input/mouse/synaptics.h
> +++ b/drivers/input/mouse/synaptics.h
> @@ -113,6 +113,7 @@ struct synaptics_data {
>   	unsigned char mode;			/* current mode byte */
>   	int scroll;
>   	int multitouch;				/* Whether device provides MT */
> +	unsigned int num_fingers;		/* Number of fingers touching */
>   };
>
>   void synaptics_module_init(void);