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

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Message-ID: <20170320050241.GB20783@jelly>
Date:   Mon, 20 Mar 2017 15:02:41 +1000
From:   Peter Hutterer <peter.hutterer@...-t.net>
To:     Andrew Duggan <aduggan@...aptics.com>
Cc:     Dmitry Torokhov <dmitry.torokhov@...il.com>,
        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>
Subject: Re: [PATCH] Input: synaptics-rmi4 - Report slot as inactive when
 contact is a palm

On Thu, Mar 16, 2017 at 05:52:07PM -0700, Andrew Duggan wrote:
> On 03/16/2017 05:04 PM, Dmitry Torokhov wrote:
> > 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.
> > 
> My intent is to notify userspace that there is a palm present. But, if
> userspace does not have code which explicitly handles the MT_TOOL_PALM type
> it won't be considered a finger. I think it is only recently that drivers
> have started reporting MT_TOOL_PALM to userspace so I'm not sure if
> libraries like libinput make use of it yet.
> 
> Starting with v4.11 some touchpads will be switching from hid-multitouch to
> the RMI4 driver and reporting palms as active results in unsuppressed palms.
> I want to avoid users from upgrading and experiencing a degradation in
> usability. In which case I can update the if statement and resubmit. This is
> basically how hid-multitouch is handling it. Maybe in the future we can add
> a parameter to enable reporting palms to userspace.

Can you send me an evemu record of that happening please? I need to see the
exact instance, e.g. when it's set, what's set before, etc. Ideally just
attach to bug 100243, thanks.

Cheers,
   Peter