Re: [PATCH 4/8 v3] Input: synaptics - add image sensor support

Hi Henrik,

Thanks for the great feedback.

On Sat, Aug 13, 2011 at 5:09 AM, Henrik Rydberg [off-list ref] wrote:

Hi Daniel,

looks good, some details below.

quoted

+static void synaptics_report_slot_empty(struct input_dev *dev, int slot)
+{
+     input_mt_slot(dev, slot);
+     input_mt_report_slot_state(dev, MT_TOOL_FINGER, false);
+}
+
+static void synaptics_report_slot_sgm(struct input_dev *dev, int slot,
+                                   const struct synaptics_hw_state *sgm)
+{
+     input_mt_slot(dev, slot);
+     input_mt_report_slot_state(dev, MT_TOOL_FINGER, true);
+     input_report_abs(dev, ABS_MT_POSITION_X, sgm->x);
+     input_report_abs(dev, ABS_MT_POSITION_Y, invert_y(sgm->y));
+     input_report_abs(dev, ABS_MT_PRESSURE, sgm->z);
+     /* SGM can sometimes contain valid width */
+     if (sgm->w >= 4)
+             input_report_abs(dev, ABS_MT_TOUCH_MAJOR, sgm->w);
+}

The ABS_MT_TOUCH_MAJOR is supposed to have zero intercept, to remain
compatible with user space handling of type A devices. Also, the scale
should match the screen/pad size, such that the actual size of the
touch area can be deduced. In addition, based on the current sensor
technologies, ABS_MT_PRESSURE and ABS_MT_TOUCH_MAJOR are normally
mutually exclusive.

All in all, I would prefer to only report width via (the single-finger
axis) ABS_TOOL_WIDTH, and only for compatibility reasons.

+
+static void synaptics_report_slot_agm(struct input_dev *dev, int slot,
+                                   const struct synaptics_hw_state *agm)
+{
+     input_mt_slot(dev, slot);
+     input_mt_report_slot_state(dev, MT_TOOL_FINGER, true);
+     input_report_abs(dev, ABS_MT_POSITION_X, agm->x);
+     input_report_abs(dev, ABS_MT_POSITION_Y, invert_y(agm->y));
+     input_report_abs(dev, ABS_MT_PRESSURE, agm->z);
+}

With ABS_MT_TOUCH_MAJOR dropped, sgm and agm seems to coincide...
....

Looks good otherwise.

Thanks,
Henrik

Ahh....  ok, this makes sense.  I missed this detail previously.
Basically:
  * Only report synaptics "w" as ABS_TOOL_WIDTH (for backwards compatibility)
  * Report synaptics "z" as ABS_MT_TOUCH_MAJOR (assuming it is really
'width of finger in surface units'), and ABS_PRESSURE (for backwards
compatibility).
  * Don't use ABS_MT_PRESSURE.
  * This will simplify agm/sgm reporting by making them both reoprt
the same axes.

I will rework these patches to do this.

Thanks,
-Dan
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