On Sat, Nov 27, 2010 at 03:39:02PM -0800, Dmitry Torokhov wrote:
> On Sat, Nov 27, 2010 at 12:46:03PM +0300, Nikolai Kondrashov wrote:
> > On 11/27/2010 12:15 PM, Dmitry Torokhov wrote:
> > >2000LPI == about 79 l/mm. How is it not useable?
> > TBH, I didn't make any real calculations.
> > The introduced error isn't very high, indeed. The vertical size of 4x3 inch
> > tablet becomes 75 mm instead of 76 mm. So maybe it's alright.
> >
> > >In mainline synaptics is the only one that does this. We do not know how
> > >many drivers in vendor trees fill and use this data nor we do not know
> > >about userspace. The fact that we were not able to locate them does not
> > >mean they do not exist. The units/mm are part of input ABI now.
> > Well, I can't argue with you here.
> > I didn't think about 3rd party drivers, TBH.
> >
> > >Right, standarize on existing UOM (which are per/mm) and then implement
> > >other UOM if theya re really needed.
> > Will this fix qualify for inclusion into 2.6.37?
>
> Yes, I believe it does.
>
> > Also, what do you think about units per radians for rotational axis?
>
How about the following?
--
Dmitry
Input: document struct input_absinfo
Add documentation for struct input_absinfo that is used in EVIOCGABS
and EVIOCSABS ioctl and specify units of measure used for reporting
resolution for an axis.
Signed-off-by: Dmitry Torokhov <dtor@xxxxxxx>
---
include/linux/input.h | 21 ++++++++++++++++++++-
1 files changed, 20 insertions(+), 1 deletions(-)
diff --git a/include/linux/input.h b/include/linux/input.h
index a50046f..a8af21d 100644
--- a/include/linux/input.h
+++ b/include/linux/input.h
@@ -47,6 +47,25 @@ struct input_id {
__u16 version;
};
+/**
+ * struct input_absinfo - used by EVIOCGABS/EVIOCSABS ioctls
+ * @value: latest reported value for the axis.
+ * @minimum: specifies minimum value for the axis.
+ * @maximum: specifies maximum value for the axis.
+ * @fuzz: specifies fuzz value that is used to filter noise from
+ * the event stream.
+ * @flat: values that are within this value will be discarded by
+ * joydev interface and reported as 0 instead.
+ * @resolution: specifies resolution for the values reported for
+ * the axis.
+ *
+ * Note that input core does not clamp reported values to the
+ * [minimum, maximum] limits, such task is left to userspace.
+ *
+ * Resolution for main axes (ABS_X, ABS_Y, ABS_Z) is reported in
+ * units per millimeter (units/mm), resolution for rotational axes
+ * (ABS_RX, ABS_RY, ABS_RZ) is reported in units per radian.
+ */
struct input_absinfo {
__s32 value;
__s32 minimum;
@@ -1134,7 +1153,7 @@ struct input_mt_slot {
* of tracked contacts
* @mtsize: number of MT slots the device uses
* @slot: MT slot currently being transmitted
- * @absinfo: array of &struct absinfo elements holding information
+ * @absinfo: array of &struct input_absinfo elements holding information
* about absolute axes (current value, min, max, flat, fuzz,
* resolution)
* @key: reflects current state of device's keys/buttons
--
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