On Thu, Jun 21, 2018 at 02:09:08PM +0200, Benjamin Tissoires wrote:
> From: Dmitry Torokhov <dmitry.torokhov@xxxxxxxxx>
>
> Usually, there is no palm rejection for touchscreens. You don't rest
> your palm on the touchscreen while interacting with it.
> However, some wacom devices do so because you can rest your palm while
> interacting with the stylus.
>
> Unfortunately, the spec for touchscreens[1] is less precise than the one
> for touchpads[2]. This leads to a situation where it's 'legitimate'
> for a touchscreen to provide both tipswitch off and confidence off in the
> same report.
>
> Work around that by keeping the slot active for one frame where we report
> MT_TOOL_PALM, and then synthesizing the release event in a separate frame.
> frame
>
> Signed-off-by: Dmitry Torokhov <dmitry.torokhov@xxxxxxxxx>
> [rebased and new commit message]
> Signed-off-by: Benjamin Tissoires <benjamin.tissoires@xxxxxxxxxx>
Acked-by: Peter Hutterer <peter.hutterer@xxxxxxxxx>
to the series unless otherwise noted.
Cheers,
Peter
> ---
> changes in v2 (compared to Dmitry's initial submission):
> - extracted from the initial submission in a separate patch
> - rebased on top of my current series
> - add an extra input_mt_sync_frame(input); to release the single touch
> emulation
>
> no changes in v3
> ---
> drivers/hid/hid-multitouch.c | 52 +++++++++++++++++++++++++++++++++++++++++++-
> 1 file changed, 51 insertions(+), 1 deletion(-)
>
> diff --git a/drivers/hid/hid-multitouch.c b/drivers/hid/hid-multitouch.c
> index 9c708aa261ee..3a1c2d80729b 100644
> --- a/drivers/hid/hid-multitouch.c
> +++ b/drivers/hid/hid-multitouch.c
> @@ -118,6 +118,9 @@ struct mt_application {
> int left_button_state; /* left button state */
> unsigned int mt_flags; /* flags to pass to input-mt */
>
> + unsigned long *pending_palm_slots; /* slots where we reported palm
> + * and need to release */
> +
> __u8 num_received; /* how many contacts we received */
> __u8 num_expected; /* expected last contact index */
> __u8 buttons_count; /* number of physical buttons per touchpad */
> @@ -863,6 +866,28 @@ static int mt_compute_slot(struct mt_device *td, struct mt_application *app,
> return input_mt_get_slot_by_key(input, *slot->contactid);
> }
>
> +static void mt_release_pending_palms(struct mt_device *td,
> + struct mt_application *app,
> + struct input_dev *input)
> +{
> + int slotnum;
> + bool need_sync = false;
> +
> + for_each_set_bit(slotnum, app->pending_palm_slots, td->maxcontacts) {
> + clear_bit(slotnum, app->pending_palm_slots);
> +
> + input_mt_slot(input, slotnum);
> + input_mt_report_slot_state(input, MT_TOOL_PALM, false);
> +
> + need_sync = true;
> + }
> +
> + if (need_sync) {
> + input_mt_sync_frame(input);
> + input_sync(input);
> + }
> +}
> +
> /*
> * this function is called when a whole packet has been received and processed,
> * so that it can decide what to send to the input layer.
> @@ -876,6 +901,9 @@ static void mt_sync_frame(struct mt_device *td, struct mt_application *app,
> input_mt_sync_frame(input);
> input_event(input, EV_MSC, MSC_TIMESTAMP, app->timestamp);
> input_sync(input);
> +
> + mt_release_pending_palms(td, app, input);
> +
> app->num_received = 0;
> app->left_button_state = 0;
>
> @@ -970,8 +998,23 @@ static int mt_process_slot(struct mt_device *td, struct input_dev *input,
>
> if (app->application == HID_GD_SYSTEM_MULTIAXIS)
> tool = MT_TOOL_DIAL;
> - else if (unlikely(!confidence_state))
> + else if (unlikely(!confidence_state)) {
> tool = MT_TOOL_PALM;
> + if (!active &&
> + input_mt_is_active(&mt->slots[slotnum])) {
> + /*
> + * The non-confidence was reported for
> + * previously valid contact that is also no
> + * longer valid. We can't simply report
> + * lift-off as userspace will not be aware
> + * of non-confidence, so we need to split
> + * it into 2 events: active MT_TOOL_PALM
> + * and a separate liftoff.
> + */
> + active = true;
> + set_bit(slotnum, app->pending_palm_slots);
> + }
> + }
>
> input_mt_slot(input, slotnum);
> input_mt_report_slot_state(input, tool, active);
> @@ -1206,6 +1249,13 @@ static int mt_touch_input_configured(struct hid_device *hdev,
> if (td->is_buttonpad)
> __set_bit(INPUT_PROP_BUTTONPAD, input->propbit);
>
> + app->pending_palm_slots = devm_kcalloc(&hi->input->dev,
> + BITS_TO_LONGS(td->maxcontacts),
> + sizeof(long),
> + GFP_KERNEL);
> + if (!app->pending_palm_slots)
> + return -ENOMEM;
> +
> ret = input_mt_init_slots(input, td->maxcontacts, app->mt_flags);
> if (ret)
> return ret;
> --
> 2.14.3
>
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