[PATCH libinput] touchpad: warn if we have invalid touchpad ranges
Yong Bakos
junk at humanoriented.com
Wed Jun 1 13:41:17 UTC 2016
On May 31, 2016, at 7:42 PM, Peter Hutterer <peter.hutterer at who-t.net> wrote:
>
> Quite a few bugs are caused by touchpad ranges being out of whack. If we get
> input events significantly outside the expected range (5% width/height as
> error margin) print a warning to the log.
>
> And add a new doc page to explain what is happening and how to fix it.
>
> Signed-off-by: Peter Hutterer <peter.hutterer at who-t.net>
Hi Peter,
FWIW, one minor nit (whildcard) I noticed, inline below.
> ---
> doc/Makefile.am | 1 +
> doc/absolute-coordinate-ranges.dox | 120 +++++++++++++++++++++++++++++++++++++
> doc/page-hierarchy.dox | 1 +
> src/evdev-mt-touchpad.c | 59 ++++++++++++++++++
> src/evdev-mt-touchpad.h | 5 ++
> 5 files changed, 186 insertions(+)
> create mode 100644 doc/absolute-coordinate-ranges.dox
>
> diff --git a/doc/Makefile.am b/doc/Makefile.am
> index f2a47cb..1e501a8 100644
> --- a/doc/Makefile.am
> +++ b/doc/Makefile.am
> @@ -11,6 +11,7 @@ header_files = \
> $(top_srcdir)/src/libinput.h \
> $(top_srcdir)/README.txt \
> $(srcdir)/absolute-axes.dox \
> + $(srcdir)/absolute-coordinate-ranges.dox \
> $(srcdir)/clickpad-softbuttons.dox \
> $(srcdir)/device-configuration-via-udev.dox \
> $(srcdir)/faqs.dox \
> diff --git a/doc/absolute-coordinate-ranges.dox b/doc/absolute-coordinate-ranges.dox
> new file mode 100644
> index 0000000..f9d9e98
> --- /dev/null
> +++ b/doc/absolute-coordinate-ranges.dox
> @@ -0,0 +1,120 @@
> +/**
> + at page absolute_coordinate_ranges Coordinate ranges for absolute axes
> +
> +libinput requires that all touchpads provide a correct axis range and
> +resolution. These are used to enable or disable certain features or adapt
> +the interaction with the touchpad. For example, the software button area is
> +narrower on small touchpads to avoid reducing the interactive surface too
> +much. Likewise, palm detection works differently on small touchpads as palm
> +interference is less likely to happen.
> +
> +Touchpads with incorrect axis ranges generate error messages
> +in the form:
> +<blockquote>
> +Axis 0x35 value 4000 is outside expected range [0, 3000]
> +</blockquote>
> +
> +This error message indicates that the ABS_MT_POSITION_X axis (i.e. the x
> +axis) generated an event outside the expected range of 0-3000. In this case
> +the value was 4000.
> +This discrepancy between the coordinate range the kernels advertises vs.
> +what the touchpad sends can be the source of a number of perceived
> +bugs in libinput.
> +
> + at section absolute_coordinate_ranges_fix Measuring and fixing touchpad ranges
> +
> +To fix the touchpad you need to:
> +-# measure the physical size of your touchpad in mm
> +-# run touchpad-edge-detector
> +-# trim the udev match rule to something sensible
> +-# replace the resolution with the calculated resolution based on physical
> + settings
> +-# test locally
> +-# send a patch to the systemd project
> +
> +Detailed explanations are below.
> +
> +[libevdev](http://freedesktop.org/wiki/Software/libevdev/) provides a tool
> +called **touchpad-edge-detector** that allows measuring the touchpad's input
> +ranges. Run the tool as root against the device node of your touchpad device
> +and repeatedly move a finger around the whole outside area of the
> +touchpad. Then control+c the process and note the output.
> +An example output is below:
> +
> + at code
> +$> sudo touchpad-edge-detector /dev/input/event4
> +Touchpad SynPS/2 Synaptics TouchPad on /dev/input/event4
> +Move one finger around the touchpad to detect the actual edges
> +Kernel says: x [1024..3112], y [2024..4832]
> +Touchpad sends: x [2445..4252], y [3464..4071]
> +
> +Touchpad size as listed by the kernel: 49x66mm
> +Calculate resolution as:
> + x axis: 2088/<width in mm>
> + y axis: 2808/<height in mm>
> +
> +Suggested udev rule:
> +# <Laptop model description goes here>
> +evdev:name:SynPS/2 Synaptics TouchPad:dmi:bvnLENOVO:bvrGJET72WW(2.22):bd02/21/2014:svnLENOVO:pn20ARS25701:pvrThinkPadT440s:rvnLENOVO:rn20ARS25701:rvrSDK0E50512STD:cvnLENOVO:ct10:cvrNotAvailable:*
> + EVDEV_ABS_00=2445:4252:<x resolution>
> + EVDEV_ABS_01=3464:4071:<y resolution>
> + EVDEV_ABS_35=2445:4252:<x resolution>
> + EVDEV_ABS_36=3464:4071:<y resolution>
> +
> + at endcode
> +
> +Note the discrepancy between the coordinate range the kernels advertises vs.
> +what the touchpad sends.
> +To fix the advertised ranges, the udev rule should be taken and trimmed
> +before being sent to the [systemd project](https://github.com/systemd/systemd).
> +An example commit can be found
> +[here](https://github.com/systemd/systemd/commit/26f667eac1c5e89b689aa0a1daef6a80f473e045).
> +
> +In most cases the match can and should be trimmed to the system vendor (svn)
> +and the product version (pvr), with everything else replaced by a wildcard
> +(*). In this case, a Lenovo T440s, a suitable match string would be: @code
> +evdev:name:SynPS/2 Synaptics TouchPad:dmi:*svnLENOVO:*pvrThinkPadT440s*
> + at endcode
> +
> + at note hwdb match strings only allow for alphanumeric ascii characters. Use a
> +whildcard (* or ?, whichever appropriate) for special characters.
wildcard
> +
> +The actual axis overrides are in the form:
> + at code
> +# axis number=min:max:resolution
> + EVDEV_ABS_00=2445:4252:42
> + at endcode
> +or, if the range is correct but the resolution is wrong
> + at code
> +# axis number=::resolution
> + EVDEV_ABS_00=::42
> + at endcode
> +
> +Note the leading single space. The axis numbers are in hex and can be found
> +in *linux/input-event-codes.h*. For touchpads ABS_X, ABS_Y,
> +ABS_MT_POSITION_X and ABS_MT_POSITION_Y are required.
> +
> + at note The touchpad's ranges and/or resolution should only be fixed when
> +there is a significant discrepancy. A few units do not make a difference and
> +a resolution that is off by 2 or less usually does not matter either.
> +
> +Once a match and override rule has been found, follow the instructions at
> +the top of the
> +[60-evdev.hwdb](https://github.com/systemd/systemd/blob/master/hwdb/60-evdev.hwdb)
> +file to save it locally and trigger the udev hwdb reload. Rebooting is
> +always a good idea. If the match string is correct, the new properties will
> +show up in the
> +output of
> + at code
> + udevadm info /sys/class/input/event4
> + at endcode
> +
> +Adjust the command for the event node of your touchpad.
> +A udev builtin will apply the new axis ranges automatically.
> +
> +When the axis override is confirmed to work, please submit it as a patch to
> +the [systemd project](https://github.com/systemd/systemd) or if that is not
> +possible as a libinput bug here:
> +https://bugs.freedesktop.org/enter_bug.cgi?product=Wayland&component=libinput
> +*/
> +
> diff --git a/doc/page-hierarchy.dox b/doc/page-hierarchy.dox
> index e47e98e..8455fca 100644
> --- a/doc/page-hierarchy.dox
> +++ b/doc/page-hierarchy.dox
> @@ -8,6 +8,7 @@
> - @subpage palm_detection
> - @subpage t440_support
> - @subpage touchpad_jumping_cursor
> +- @subpage absolute_coordinate_ranges
>
> @page touchscreens Touchscreens
>
> diff --git a/src/evdev-mt-touchpad.c b/src/evdev-mt-touchpad.c
> index 61d955a..a7b7a68 100644
> --- a/src/evdev-mt-touchpad.c
> +++ b/src/evdev-mt-touchpad.c
> @@ -289,6 +289,39 @@ tp_get_delta(struct tp_touch *t)
> return tp_normalize_delta(t->tp, delta);
> }
>
> +static inline void
> +tp_check_axis_range(struct tp_dispatch *tp,
> + unsigned int code,
> + int value)
> +{
> + int min, max;
> +
> + switch(code) {
> + case ABS_X:
> + case ABS_MT_POSITION_X:
> + min = tp->warning_range.min.x;
> + max = tp->warning_range.max.x;
> + break;
> + case ABS_Y:
> + case ABS_MT_POSITION_Y:
> + min = tp->warning_range.min.y;
> + max = tp->warning_range.max.y;
> + break;
> + default:
> + return;
> + }
> +
> + if (value < min || value > max) {
> + log_info_ratelimit(tp_libinput_context(tp),
> + &tp->warning_range.range_warn_limit,
> + "Axis %#x value %d is outside expected range [%d, %d]\n"
> + "See %s/absolute_coordinate_ranges.html for details\n",
> + code, value, min, max,
> + HTTP_DOC_LINK);
> +
> + }
> +}
> +
> static void
> tp_process_absolute(struct tp_dispatch *tp,
> const struct input_event *e,
> @@ -298,12 +331,14 @@ tp_process_absolute(struct tp_dispatch *tp,
>
> switch(e->code) {
> case ABS_MT_POSITION_X:
> + tp_check_axis_range(tp, e->code, e->value);
> t->point.x = e->value;
> t->millis = time;
> t->dirty = true;
> tp->queued |= TOUCHPAD_EVENT_MOTION;
> break;
> case ABS_MT_POSITION_Y:
> + tp_check_axis_range(tp, e->code, e->value);
> t->point.y = e->value;
> t->millis = time;
> t->dirty = true;
> @@ -339,12 +374,14 @@ tp_process_absolute_st(struct tp_dispatch *tp,
>
> switch(e->code) {
> case ABS_X:
> + tp_check_axis_range(tp, e->code, e->value);
> t->point.x = e->value;
> t->millis = time;
> t->dirty = true;
> tp->queued |= TOUCHPAD_EVENT_MOTION;
> break;
> case ABS_Y:
> + tp_check_axis_range(tp, e->code, e->value);
> t->point.y = e->value;
> t->millis = time;
> t->dirty = true;
> @@ -2063,6 +2100,26 @@ want_hysteresis:
> return;
> }
>
> +static void
> +tp_init_range_warnings(struct tp_dispatch *tp,
> + struct evdev_device *device,
> + int width,
> + int height)
> +{
> + const struct input_absinfo *x, *y;
> +
> + x = device->abs.absinfo_x;
> + y = device->abs.absinfo_y;
> +
> + tp->warning_range.min.x = x->minimum - 0.05 * width;
> + tp->warning_range.min.y = y->minimum - 0.05 * height;
> + tp->warning_range.max.x = x->maximum + 0.05 * width;
> + tp->warning_range.max.y = y->maximum + 0.05 * height;
> +
> + /* One warning every 5 min is enough */
> + ratelimit_init(&tp->warning_range.range_warn_limit, s2us(3000), 1);
> +}
> +
> static int
> tp_init(struct tp_dispatch *tp,
> struct evdev_device *device)
> @@ -2086,6 +2143,8 @@ tp_init(struct tp_dispatch *tp,
> height = device->abs.dimensions.y;
> diagonal = sqrt(width*width + height*height);
>
> + tp_init_range_warnings(tp, device, width, height);
> +
> tp->reports_distance = libevdev_has_event_code(device->evdev,
> EV_ABS,
> ABS_MT_DISTANCE);
> diff --git a/src/evdev-mt-touchpad.h b/src/evdev-mt-touchpad.h
> index cbc33aa..1efe25c 100644
> --- a/src/evdev-mt-touchpad.h
> +++ b/src/evdev-mt-touchpad.h
> @@ -245,6 +245,11 @@ struct tp_dispatch {
> struct device_coords hysteresis_margin;
>
> struct {
> + struct device_coords min, max;
> + struct ratelimit range_warn_limit;
> + } warning_range;
> +
> + struct {
> double x_scale_coeff;
> double y_scale_coeff;
> } accel;
> --
> 2.7.4
yong
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