linux-kernel - Re: [PATCH 5/6] hid: egalax: Add event filtering

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Date:	Wed, 13 Oct 2010 13:55:13 -0400
From:	Chase Douglas <chase.douglas@...onical.com>
To:	Henrik Rydberg <rydberg@...omail.se>
Cc:	Jiri Kosina <jkosina@...e.cz>,
	Dmitry Torokhov <dmitry.torokhov@...il.com>,
	Philipp Merkel <mail@...lmerk.de>,
	Stephane Chatty <chatty@...c.fr>, linux-input@...r.kernel.org,
	linux-kernel@...r.kernel.org
Subject: Re: [PATCH 5/6] hid: egalax: Add event filtering

On Wed, 2010-10-13 at 15:58 +0200, Henrik Rydberg wrote:
> Use estimated signal-to-noise ratios to reduce noise and limit the
> amount of events emitted.
> 
> Signed-off-by: Henrik Rydberg <rydberg@...omail.se>
> ---
>  drivers/hid/hid-egalax.c |   16 ++++++++++------
>  1 files changed, 10 insertions(+), 6 deletions(-)
> 
> diff --git a/drivers/hid/hid-egalax.c b/drivers/hid/hid-egalax.c
> index 2aba897..b21e7dc 100644
> --- a/drivers/hid/hid-egalax.c
> +++ b/drivers/hid/hid-egalax.c
> @@ -27,6 +27,10 @@ MODULE_LICENSE("GPL");
>  
>  #define MAX_EVENTS		120
>  
> +/* estimated signal-to-noise ratios */
> +#define SN_MOVE			1024
> +#define SN_PRESSURE		32
> +
>  struct egalax_data {
>  	__u16 x, y, z;
>  	__u8 id;
> @@ -59,17 +63,17 @@ static int egalax_input_mapping(struct hid_device *hdev, struct hid_input *hi,
>  			field->logical_maximum <<= 3;
>  			hid_map_usage(hi, usage, bit, max,
>  					EV_ABS, ABS_MT_POSITION_X);
> -			set_abs(input, ABS_MT_POSITION_X, field, 0);
> +			set_abs(input, ABS_MT_POSITION_X, field, SN_MOVE);
>  			/* touchscreen emulation */
> -			set_abs(input, ABS_X, field, 0);
> +			set_abs(input, ABS_X, field, SN_MOVE);
>  			return 1;
>  		case HID_GD_Y:
>  			field->logical_maximum <<= 3;
>  			hid_map_usage(hi, usage, bit, max,
>  					EV_ABS, ABS_MT_POSITION_Y);
> -			set_abs(input, ABS_MT_POSITION_Y, field, 0);
> +			set_abs(input, ABS_MT_POSITION_Y, field, SN_MOVE);
>  			/* touchscreen emulation */
> -			set_abs(input, ABS_Y, field, 0);
> +			set_abs(input, ABS_Y, field, SN_MOVE);
>  			return 1;
>  		}
>  		return 0;
> @@ -96,9 +100,9 @@ static int egalax_input_mapping(struct hid_device *hdev, struct hid_input *hi,
>  			field->logical_minimum = 0;
>  			hid_map_usage(hi, usage, bit, max,
>  					EV_ABS, ABS_MT_PRESSURE);
> -			set_abs(input, ABS_MT_PRESSURE, field, 0);
> +			set_abs(input, ABS_MT_PRESSURE, field, SN_PRESSURE);
>  			/* touchscreen emulation */
> -			set_abs(input, ABS_PRESSURE, field, 0);
> +			set_abs(input, ABS_PRESSURE, field, SN_PRESSURE);
>  			return 1;
>  		}
>  		return 0;

Seems obvious.

Acked-by: Chase Douglas <chase.douglas@...onical.com>

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