Possible regression with "Add hysteresis-based noise reduction" in synaptics driver

[Peter Clifton]

Hi guys,

Recently I've been having some difficulties with my touchpad. I do a lot
of electronics design work, and this often requires making small precise
movements with the pointer.

Just recently though, this has been much harder - I've found myself
getting frustrated with the CAD package, and I'd started to think my
touchpad was broken... (so I started investigating). It definitely
seemed that I was unable to persuade the touchpad to produce smooth
motions of a small number of pixels.

I tried drawing some circles using the touchpad, and they would come out
with flattened edges.

I found that by setting the "Synaptics Noise Cancellation" property
using "xinput", I was able to restore "correct" behaviour. I guess the
default setting is picking up a default which is not well suited to my
laptop (HP 6730b) hardware.

Any pointers (no pun intended) you can suggest to investigate why the
default is inappropriate on my system would be great. I'll try to follow
up with what the default _is_ on this box when I next reboot. For now,
I've been fixing the issue with:

xinput set-int-prop 11 313 32 10 10

So I don't have the old setting readily to hand. (I did attach the
current settings. I've only modified the noise cancellation one).

Thanks

-- 
Peter Clifton <pcjc2 at cam.ac.uk>
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Device 'SynPS/2 Synaptics TouchPad':
	Device Enabled (152):	1
	Coordinate Transformation Matrix (154):	1.000000, 0.000000, 0.000000, 0.000000, 1.000000, 0.000000, 0.000000, 0.000000, 1.000000
	Device Accel Profile (274):	1
	Device Accel Constant Deceleration (275):	2.500000
	Device Accel Adaptive Deceleration (276):	1.000000
	Device Accel Velocity Scaling (277):	12.500000
	Synaptics Edges (278):	1758, 5274, 1643, 4543
	Synaptics Finger (279):	25, 30, 256
	Synaptics Tap Time (280):	180
	Synaptics Tap Move (281):	233
	Synaptics Tap Durations (282):	180, 180, 100
	Synaptics Tap FastTap (283):	0
	Synaptics Middle Button Timeout (284):	75
	Synaptics Two-Finger Pressure (285):	282
	Synaptics Two-Finger Width (286):	7
	Synaptics Scrolling Distance (287):	105, 105
	Synaptics Edge Scrolling (288):	1, 0, 0
	Synaptics Two-Finger Scrolling (289):	0, 0
	Synaptics Move Speed (290):	1.000000, 1.750000, 0.037757, 40.000000
	Synaptics Edge Motion Pressure (291):	30, 160
	Synaptics Edge Motion Speed (292):	1, 423
	Synaptics Edge Motion Always (293):	0
	Synaptics Off (294):	0
	Synaptics Locked Drags (295):	0
	Synaptics Locked Drags Timeout (296):	5000
	Synaptics Tap Action (297):	2, 3, 0, 0, 1, 3, 2
	Synaptics Click Action (298):	1, 1, 1
	Synaptics Circular Scrolling (299):	0
	Synaptics Circular Scrolling Distance (300):	0.100000
	Synaptics Circular Scrolling Trigger (301):	0
	Synaptics Circular Pad (302):	0
	Synaptics Palm Detection (303):	0
	Synaptics Palm Dimensions (304):	10, 200
	Synaptics Coasting Speed (305):	20.000000, 50.000000
	Synaptics Pressure Motion (306):		... of unknown type CARDINAL

	Synaptics Pressure Motion Factor (307):	1.000000, 1.000000
	Synaptics Grab Event Device (308):	1
	Synaptics Gestures (309):	1
	Synaptics Capabilities (310):	1, 0, 1, 0, 0, 1, 1
	Synaptics Pad Resolution (311):	100, 53
	Synaptics Area (312):	0, 0, 0, 0
	Synaptics Noise Cancellation (313):	10, 10
	Device Product ID (272):	2, 7
	Device Node (273):	"/dev/input/event7"
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