linux-kernel - Re: [PATCH 2/4] Input: synaptics

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Message-ID: <AANLkTinso7BZB4GxgsQshaGeka+CcjUtjB9Agdj3qFnz@mail.gmail.com>
Date:	Sat, 18 Dec 2010 11:05:08 -0600
From:	Chris Bagwell <chris@...bagwell.com>
To:	Henrik Rydberg <rydberg@...omail.se>
Cc:	Dmitry Torokhov <dmitry.torokhov@...il.com>,
	Jiri Kosina <jkosina@...e.cz>,
	Chase Douglas <chase.douglas@...onical.com>,
	linux-input@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH 2/4] Input: synaptics - ignore bogus mt packet

On Sat, Dec 18, 2010 at 8:52 AM, Henrik Rydberg <rydberg@...omail.se> wrote:
> In multitouch mode, at least one device (fw: 7.4 id: 0x1c0b1) sometimes
> sends a final main packet with x == 1. Since the normal values are above
> 1472, this is clearly bogus. At the same time, a two-finger touch is
> signaled, even though only one finger was on the pad to begin with. This
> patch ignores the packet altogether, removing the problem.

I've seen this behavior as well although I thought it always came when
hw.z == 0 so was masked.  I guess its not to surprising its sneaking
threw with low pressures.

>
> Signed-off-by: Henrik Rydberg <rydberg@...omail.se>
> ---
>  drivers/input/mouse/synaptics.c |    4 ++--
>  1 files changed, 2 insertions(+), 2 deletions(-)
>
> diff --git a/drivers/input/mouse/synaptics.c b/drivers/input/mouse/synaptics.c
> index 8a769e9..4744064 100644
> --- a/drivers/input/mouse/synaptics.c
> +++ b/drivers/input/mouse/synaptics.c
> @@ -526,7 +526,7 @@ static void synaptics_process_packet(struct psmouse *psmouse)
>                return;
>        }
>
> -       if (hw.z > 0) {
> +       if (hw.z > 0 && hw.x > 1) {
>                num_fingers = 1;
>                finger_width = 5;
>                if (SYN_CAP_EXTENDED(priv->capabilities)) {
> @@ -558,7 +558,7 @@ static void synaptics_process_packet(struct psmouse *psmouse)
>        if (hw.z > 30) input_report_key(dev, BTN_TOUCH, 1);
>        if (hw.z < 25) input_report_key(dev, BTN_TOUCH, 0);
>
> -       if (hw.z > 0) {
> +       if (hw.z > 0 && hw.x > 1) {
>                input_report_abs(dev, ABS_X, hw.x);
>                input_report_abs(dev, ABS_Y, YMAX_NOMINAL + YMIN_NOMINAL - hw.y);
>        }

This might read better if we change to "if (num_fingers) {" and then
we do not need to repeat the hw work around logic twice.

Also, this snippet shows I may be seeing it as well but the
BTN_TOUCH=0 when < 25 is probably masking it for most cases.

Either way:

Acked-by: Chris Bagwell <chris@...bagwell.com>

Chris
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