linux-kernel - Re: [PATCH 2/2] input: synaptics - fix width calculation on image sensors

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Date:	Mon, 5 Jan 2015 13:25:38 -0500
From:	Benjamin Tissoires <benjamin.tissoires@...il.com>
To:	Gabriele Mazzotta <gabriele.mzt@...il.com>
Cc:	Dmitry Torokhov <dmitry.torokhov@...il.com>,
	Henrik Rydberg <rydberg@...omail.se>,
	linux-input <linux-input@...r.kernel.org>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	silverhammermba@...il.com
Subject: Re: [PATCH 2/2] input: synaptics - fix width calculation on image sensors

Hi Gabriele,

On Sat, Dec 27, 2014 at 6:31 AM, Gabriele Mazzotta
<gabriele.mzt@...il.com> wrote:
> When two or more fingers are on the touchpad, the 'w' slot holds the
> finger count rather than the width. Retrieve the correct value encoded
> in the lower bits of 'x', 'y' and 'z'.
>
> The minimum width reported is 8 rather than 4 in this case, while the
> maximum remains 15.
>
> Signed-off-by: Gabriele Mazzotta <gabriele.mzt@...il.com>
> ---
>  drivers/input/mouse/synaptics.c | 4 +++-
>  1 file changed, 3 insertions(+), 1 deletion(-)
>
> diff --git a/drivers/input/mouse/synaptics.c b/drivers/input/mouse/synaptics.c
> index ea0563e..5ff4c5b 100644
> --- a/drivers/input/mouse/synaptics.c
> +++ b/drivers/input/mouse/synaptics.c
> @@ -593,7 +593,9 @@ static void synaptics_parse_agm(const unsigned char buf[],
>         switch (agm_packet_type) {
>         case 1:
>                 /* Gesture packet: (x, y, z) half resolution */
> -               agm->w = hw->w;
> +               agm->w = ((buf[1] & 0x01) |
> +                         ((buf[2] & 0x01) << 1) |
> +                         ((buf[5] & 0x01) << 2)) + 8;
>                 agm->x = (((buf[4] & 0x0f) << 8) | buf[1]) << 1;

For completeness, I think, we should also removes the w bits from x, y
and z (by masking buf[1], buf[2] and buf[5] with 0xfe).

Cheers,
Benjamin

>                 agm->y = (((buf[4] & 0xf0) << 4) | buf[2]) << 1;
>                 agm->z = ((buf[3] & 0x30) | (buf[5] & 0x0f)) << 1;
> --
> 2.1.4
>
> --
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