Hi,
On 31-07-15 01:36, Peter Hutterer wrote:
On Thu, Jul 30, 2015 at 04:45:04PM +0200, Hans de Goede wrote:
Hi,
On 30-07-15 14:33, Hans de Goede wrote:
Hi,
On 30-07-15 08:11, Peter Hutterer wrote:
The first finger is accurate, it's just the second finger that is imprecise,
so we can't handle it as a true touch. Instead, revert the device back to
being a single-touch touchpad and use the fake touch bits for second finger
handling.
Two-finger scrolling thus becomes usable though we will lose out on
other features like thumb detection. Useful scrolling trumps that though.
I think we should wait with doing this until the scroll situation is more
clear, see my last comment here:
https://bugzilla.redhat.com/show_bug.cgi?id=1235175
Ok so Benjamin responded in the bug report, these touchpads
report accurate single touch data in the old-style single-touch
events, and inaccurate data in the mt events when 2 fingers are down.
So this patch which switches things over to using st coordinates
is the right thing todo. Review inline.
Signed-off-by: Peter Hutterer <[email protected]>
---
src/evdev-mt-touchpad.c | 19 ++++++++++++++-----
test/touchpad-tap.c | 3 +++
test/touchpad.c | 9 +++------
3 files changed, 20 insertions(+), 11 deletions(-)
diff --git a/src/evdev-mt-touchpad.c b/src/evdev-mt-touchpad.c
index af1cd47..54ea819 100644
--- a/src/evdev-mt-touchpad.c
+++ b/src/evdev-mt-touchpad.c
@@ -1465,6 +1465,19 @@ tp_init_slots(struct tp_dispatch *tp,
tp->semi_mt = libevdev_has_property(device->evdev, INPUT_PROP_SEMI_MT);
+ /* This device has a terrible 2fg resolution, but only for the
+ * second finger, causing scroll jumps when we use the touch points
+ * properly. The first finger resolution is accurate though, so
+ * we simply pretend it's a single touch touchpad with the BTN_TOOL
+ * bits.
+ */
This comment is wrong, the old-style st coordinates report accurate
data where as the mt data reports inaccurate data for both fingers
when 2 fingers are down. What is happening is that when a single finger
is down the st data is copied over to the mt data slot 0, so as to
have something to report to user-space which only listens to mt events,
and as soon as a second finger comes down the driver starts reporting
the bounding box limits in the mt data, making *both* slots inaccurate.
So it is not "only for the second finger" nor is "The first finger
resolution is accurate" really accurate to say :) The first finger as
reported in the st events is accurate, the first finger reported in the
mt events is still no good, otherwise we would not need this commit at
all.
ok, I've amended the comment to:
+ /* This device has a terrible resolution when two fingers are down,
+ * causing scroll jumps. The single-touch emulation ABS_X/Y is
+ * accurate but the ABS_MT_POSITION touchpoints report the bounding
+ * box and that causes jumps. So we simply pretend it's a single
+ * touch touchpad with the BTN_TOOL bits.
+ * See https://bugzilla.redhat.com/show_bug.cgi?id=1235175 for an
+ * explanation.
I hope that's close enough now, let me know if you want me to amend this
further. Worst case, the bugzilla link has the more detailed comments :)
That is fine, thanks.
Regards,
Hans
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