linux-kernel - Re: [PATCH] Input: synaptics-rmi4 - Report slot as inactive when contact is a palm

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Date:   Thu, 16 Mar 2017 17:04:50 -0700
From:   Dmitry Torokhov <dmitry.torokhov@...il.com>
To:     Andrew Duggan <aduggan@...aptics.com>
Cc:     linux-input@...r.kernel.org, linux-kernel@...r.kernel.org,
        Jiri Kosina <jikos@...nel.org>,
        Benjamin Tissoires <benjamin.tissoires@...hat.com>,
        Cameron Gutman <aicommander@...il.com>,
        Thorsten Leemhuis <linux@...mhuis.info>,
        Christopher Heiny <cheiny@...aptics.com>,
        Nick Dyer <nick@...anahar.org>,
        Peter Hutterer <peter.hutterer@...-t.net>
Subject: Re: [PATCH] Input: synaptics-rmi4 - Report slot as inactive when
 contact is a palm

On Thu, Mar 16, 2017 at 04:56:31PM -0700, Andrew Duggan wrote:
> When the firmware identifies a contact as a palm the driver sets the tool
> type to MT_TOOL_PALM, but sets the slot state as active. Reporting the
> palm as active results in userspace input libraries considering the palm
> as a valid contact. Touchpads which previously were using hid-multitouch
> are now not suppressing palms when switching to the RMI4 driver. This
> change fixes palm rejection when using the RMI4 driver.
> 
> Signed-off-by: Andrew Duggan <aduggan@...aptics.com>
> Tested-by: Cameron Gutman <aicommander@...il.com>
> ---
>  drivers/input/rmi4/rmi_2d_sensor.c | 3 ++-
>  1 file changed, 2 insertions(+), 1 deletion(-)
> 
> diff --git a/drivers/input/rmi4/rmi_2d_sensor.c b/drivers/input/rmi4/rmi_2d_sensor.c
> index 8bb866c..8d1f295 100644
> --- a/drivers/input/rmi4/rmi_2d_sensor.c
> +++ b/drivers/input/rmi4/rmi_2d_sensor.c
> @@ -80,7 +80,8 @@ void rmi_2d_sensor_abs_report(struct rmi_2d_sensor *sensor,
>  		input_mt_slot(input, slot);
>  
>  	input_mt_report_slot_state(input, obj->mt_tool,
> -				   obj->type != RMI_2D_OBJECT_NONE);
> +				   (obj->type != RMI_2D_OBJECT_NONE)
> +				   && (obj->type != RMI_2D_OBJECT_PALM));
>  
>  	if (obj->type != RMI_2D_OBJECT_NONE) {
>  		obj->x = sensor->tracking_pos[slot].x;

If we are relying on hardware to do palm rejection, then we should not
be reporting the rest of the events for palm either (i.e. the condition
in the if statement above should also be updated).

But I do not understand why userspace doe snot do the right thing? Yes,
the slot is active, but reported contact type is MT_TOOL_PALM, so it
knows what it deals with.

Thanks.

-- 
Dmitry