Re: [PATCH v3] HID: hid-multitouch: support fine-grain orientation reporting

[Benjamin Tissoires]

Hi,

On Oct 05 2017 or thereabouts, Jiri Kosina wrote:
> 
> [ adding Benjamin to CC ]
> 
> On Thu, 28 Sep 2017, Wei-Ning Huang wrote:
> 
> > The current hid-multitouch driver only allow the report of two
> > orientations, vertical and horizontal. We use the Azimuth orientation
> > usage 0x3F under the Digitizer usage page to report orientation if the
> > device supports it.
> > 
> > Changelog:
> >   v1 -> v2:
> >    - Fix commit message.
> >    - Remove resolution reporting for ABS_MT_ORIENTATION.
> >   v2 -> v3:
> >    - Fix commit message.
> > 
> > Signed-off-by: Wei-Ning Huang <wnhuang@xxxxxxxxxx>
> > Reviewed-by: Dmitry Torokhov <dtor@xxxxxxxxxxxx>
> > ---
> >  drivers/hid/hid-multitouch.c | 35 +++++++++++++++++++++++++++++++++--
> >  include/linux/hid.h          |  1 +
> >  2 files changed, 34 insertions(+), 2 deletions(-)
> > 
> > diff --git a/drivers/hid/hid-multitouch.c b/drivers/hid/hid-multitouch.c
> > index 440b999304a5..f9801d1b1eae 100644
> > --- a/drivers/hid/hid-multitouch.c
> > +++ b/drivers/hid/hid-multitouch.c
> > @@ -84,11 +84,12 @@ MODULE_LICENSE("GPL");
> >  #define MT_IO_FLAGS_PENDING_SLOTS	2
> >  
> >  struct mt_slot {
> > -	__s32 x, y, cx, cy, p, w, h;
> > +	__s32 x, y, cx, cy, p, w, h, a;
> >  	__s32 contactid;	/* the device ContactID assigned to this slot */
> >  	bool touch_state;	/* is the touch valid? */
> >  	bool inrange_state;	/* is the finger in proximity of the sensor? */
> >  	bool confidence_state;  /* is the touch made by a finger? */
> > +	bool has_azimuth;       /* the contact reports azimuth */
> >  };
> >  
> >  struct mt_class {
> > @@ -591,6 +592,20 @@ static int mt_touch_input_mapping(struct hid_device *hdev, struct hid_input *hi,
> >  			td->cc_index = field->index;
> >  			td->cc_value_index = usage->usage_index;
> >  			return 1;
> > +		case HID_DG_AZIMUTH:
> > +			hid_map_usage(hi, usage, bit, max,
> > +				EV_ABS, ABS_MT_ORIENTATION);
> > +			/*
> > +			 * Azimuth has the range of [0, MAX) representing a full
> > +			 * revolution. Set ABS_MT_ORIENTATION to a quarter of
> > +			 * MAX according the definition of ABS_MT_ORIENTATION
> > +			 */
> > +			input_set_abs_params(hi->input, ABS_MT_ORIENTATION,
> > +				0, field->logical_maximum / 4,

Shouldn't this be "-field->logical_maximum / 4, field->logical_maximum / 4,"?

Also, if HID_DG_HEIGHT is seen after HID_DG_AZIMUTH, it'll change the
ABS_MT_ORIENTATION you just set here.

> > +				cls->sn_move ?
> > +				field->logical_maximum / cls->sn_move : 0, 0);
> > +			mt_store_field(usage, td, hi);
> > +			return 1;
> >  		case HID_DG_CONTACTMAX:
> >  			/* we don't set td->last_slot_field as contactcount and
> >  			 * contact max are global to the report */
> > @@ -683,6 +698,10 @@ static void mt_complete_slot(struct mt_device *td, struct input_dev *input)
> >  			int wide = (s->w > s->h);
> >  			int major = max(s->w, s->h);
> >  			int minor = min(s->w, s->h);
> > +			int orientation = wide;
> > +
> > +			if (s->has_azimuth)
> > +				orientation = s->a;
> >  
> >  			/*
> >  			 * divided by two to match visual scale of touch
> > @@ -699,7 +718,8 @@ static void mt_complete_slot(struct mt_device *td, struct input_dev *input)
> >  			input_event(input, EV_ABS, ABS_MT_TOOL_Y, s->cy);
> >  			input_event(input, EV_ABS, ABS_MT_DISTANCE,
> >  				!s->touch_state);
> > -			input_event(input, EV_ABS, ABS_MT_ORIENTATION, wide);
> > +			input_event(input, EV_ABS, ABS_MT_ORIENTATION,
> > +				orientation);
> >  			input_event(input, EV_ABS, ABS_MT_PRESSURE, s->p);
> >  			input_event(input, EV_ABS, ABS_MT_TOUCH_MAJOR, major);
> >  			input_event(input, EV_ABS, ABS_MT_TOUCH_MINOR, minor);
> > @@ -789,6 +809,17 @@ static void mt_process_mt_event(struct hid_device *hid, struct hid_field *field,
> >  			break;
> >  		case HID_DG_CONTACTCOUNT:
> >  			break;
> > +		case HID_DG_AZIMUTH:
> > +			/*
> > +			 * Azimuth is counter-clockwise and ranges from [0, MAX)
> > +			 * (a full revolution). Convert it to clockwise ranging
> > +			 * [-MAX/2, MAX/2].

It took me a while to get this right. The problem is the definition of
ABS_MT_ORIENTATION says that we report [-MAX/4, MAX/4], *but* we can go
out of range to [-MAX/2, MAX/2] to report upside down ellipsis.

So this is correct, but I'd like to have some mention of [-MAX/4, MAX/4]
in this comment, to ease further rereading of the code.

Cheers,
Benjamin

> > +			 */
> > +			if (value > field->logical_maximum / 2)
> > +				value -= field->logical_maximum;
> > +			td->curdata.a = -value;
> > +			td->curdata.has_azimuth = true;
> > +			break;
> >  		case HID_DG_TOUCH:
> >  			/* do nothing */
> >  			break;
> > diff --git a/include/linux/hid.h b/include/linux/hid.h
> > index ab05a86269dc..d81b9b6fd83a 100644
> > --- a/include/linux/hid.h
> > +++ b/include/linux/hid.h
> > @@ -281,6 +281,7 @@ struct hid_item {
> >  
> >  #define HID_DG_DEVICECONFIG	0x000d000e
> >  #define HID_DG_DEVICESETTINGS	0x000d0023
> > +#define HID_DG_AZIMUTH		0x000d003f
> >  #define HID_DG_CONFIDENCE	0x000d0047
> >  #define HID_DG_WIDTH		0x000d0048
> >  #define HID_DG_HEIGHT		0x000d0049
> > -- 
> > 2.12.2
> > 
> 
> -- 
> Jiri Kosina
> SUSE Labs
>