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SubjectRe: [PATCH 09/19] Input: MT - Handle frame synchronization in core
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Hi Henrik,

thanks for this patch set.
I'm also happy when someone tries to factorize and optimize some code.
I have a few concerns though:

On Sun, Aug 12, 2012 at 11:42 PM, Henrik Rydberg <rydberg@euromail.se> wrote:
> Collect common frame synchronization tasks in a new function,
> input_mt_sync_frame(). Depending on the flags set, it drops
> unseen contacts and performs pointer emulation.

I was really wondering why you needed to put in input-mt something
that appeared only in hid-multitouch.... until I noted that you are
going to use it for bcm5974.
Maybe you should add a comment on it (otherwise, it seams like you're
just adding unused code). Maybe this would also help people
understanding the *frame thing.

>
> Signed-off-by: Henrik Rydberg <rydberg@euromail.se>
> ---
> drivers/input/input-mt.c | 74 ++++++++++++++++++++++++++++++++++++++++++++++--
> include/linux/input/mt.h | 9 ++++++
> 2 files changed, 81 insertions(+), 2 deletions(-)
>
> diff --git a/drivers/input/input-mt.c b/drivers/input/input-mt.c
> index bbb3304..21b105e 100644
> --- a/drivers/input/input-mt.c
> +++ b/drivers/input/input-mt.c
> @@ -14,6 +14,14 @@
>
> #define TRKID_SGN ((TRKID_MAX + 1) >> 1)
>
> +static void copy_abs(struct input_dev *dev, unsigned int dst, unsigned int src)
> +{
> + if (dev->absinfo && test_bit(src, dev->absbit)) {
> + dev->absinfo[dst] = dev->absinfo[src];
> + dev->absbit[BIT_WORD(dst)] |= BIT_MASK(dst);
> + }
> +}
> +
> /**
> * input_mt_init_slots() - initialize MT input slots
> * @dev: input device supporting MT events and finger tracking
> @@ -45,6 +53,28 @@ int input_mt_init_slots(struct input_dev *dev, unsigned int num_slots,
> input_set_abs_params(dev, ABS_MT_SLOT, 0, num_slots - 1, 0, 0);
> input_set_abs_params(dev, ABS_MT_TRACKING_ID, 0, TRKID_MAX, 0, 0);
>
> + if (flags & (INPUT_MT_POINTER | INPUT_MT_DIRECT)) {
> + __set_bit(EV_KEY, dev->evbit);
> + __set_bit(BTN_TOUCH, dev->keybit);
> +
> + copy_abs(dev, ABS_X, ABS_MT_POSITION_X);
> + copy_abs(dev, ABS_Y, ABS_MT_POSITION_Y);
> + copy_abs(dev, ABS_PRESSURE, ABS_MT_PRESSURE);
> + }
> + if (flags & INPUT_MT_POINTER) {
> + __set_bit(BTN_TOOL_FINGER, dev->keybit);
> + __set_bit(BTN_TOOL_DOUBLETAP, dev->keybit);
> + if (num_slots >= 3)
> + __set_bit(BTN_TOOL_TRIPLETAP, dev->keybit);
> + if (num_slots >= 4)
> + __set_bit(BTN_TOOL_QUADTAP, dev->keybit);
> + if (num_slots >= 5)
> + __set_bit(BTN_TOOL_QUINTTAP, dev->keybit);
> + __set_bit(INPUT_PROP_POINTER, dev->propbit);
> + }
> + if (flags & INPUT_MT_DIRECT)
> + __set_bit(INPUT_PROP_DIRECT, dev->propbit);
> +
> /* Mark slots as 'unused' */
> for (i = 0; i < num_slots; i++)
> input_mt_set_value(&mt->slots[i], ABS_MT_TRACKING_ID, -1);
> @@ -87,12 +117,17 @@ void input_mt_report_slot_state(struct input_dev *dev,
> struct input_mt_slot *slot;
> int id;
>
> - if (!mt || !active) {
> + if (!mt)
> + return;
> +
> + slot = &mt->slots[input_abs_get_val(dev, ABS_MT_SLOT)];
> + slot->frame = mt->frame;
> +
> + if (!active) {
> input_event(dev, EV_ABS, ABS_MT_TRACKING_ID, -1);
> return;
> }
>
> - slot = &mt->slots[input_abs_get_val(dev, ABS_MT_SLOT)];
> id = input_mt_get_value(slot, ABS_MT_TRACKING_ID);
> if (id < 0 || input_mt_get_value(slot, ABS_MT_TOOL_TYPE) != tool_type)
> id = input_mt_new_trkid(mt);
> @@ -177,3 +212,38 @@ void input_mt_report_pointer_emulation(struct input_dev *dev, bool use_count)
> }
> }
> EXPORT_SYMBOL(input_mt_report_pointer_emulation);
> +
> +/**
> + * input_mt_sync_frame() - synchronize mt frame
> + * @dev: input device with allocated MT slots
> + *
> + * Close the frame and prepare the internal state for a new one.
> + * Depending on the flags, marks unused slots as inactive and performs
> + * pointer emulation.
> + */
> +void input_mt_sync_frame(struct input_dev *dev)
> +{
> + struct input_mt *mt = dev->mt;
> + struct input_mt_slot *s;
> +
> + if (!mt)
> + return;
> +
> + if (mt->flags & INPUT_MT_DROP_UNUSED) {
> + for (s = mt->slots; s != mt->slots + mt->num_slots; s++) {
> + if (s->frame == mt->frame)
> + continue;
> + input_mt_slot(dev, s - mt->slots);
> + input_event(dev, EV_ABS, ABS_MT_TRACKING_ID, -1);

Shouldn't we rely on input_mt_report_slot_state instead of doing it by hand?

> + }
> + }
> +
> + if (mt->flags & INPUT_MT_POINTER)
> + input_mt_report_pointer_emulation(dev, true);
> +
> + if (mt->flags & INPUT_MT_DIRECT)
> + input_mt_report_pointer_emulation(dev, false);

The function input_mt_report_pointer_emulation could be called twice
if the driver has both INPUT_MT_POINTER and INPUT_MT_DIRECT flags. Are
they mutual exclusive?
Cheers,
Benjamin

> +
> + mt->frame++;
> +}
> +EXPORT_SYMBOL(input_mt_sync_frame);
> diff --git a/include/linux/input/mt.h b/include/linux/input/mt.h
> index 03c52ce..a11d485 100644
> --- a/include/linux/input/mt.h
> +++ b/include/linux/input/mt.h
> @@ -15,12 +15,17 @@
>
> #define TRKID_MAX 0xffff
>
> +#define INPUT_MT_POINTER 0x0001 /* pointer device, e.g. trackpad */
> +#define INPUT_MT_DIRECT 0x0002 /* direct device, e.g. touchscreen */
> +#define INPUT_MT_DROP_UNUSED 0x0004 /* drop contacts not seen in frame */
> /**
> * struct input_mt_slot - represents the state of an input MT slot
> * @abs: holds current values of ABS_MT axes for this slot
> + * @frame: last frame at which input_mt_report_slot_state() was called
> */
> struct input_mt_slot {
> int abs[ABS_MT_LAST - ABS_MT_FIRST + 1];
> + unsigned int frame;
> };
>
> /**
> @@ -28,12 +33,14 @@ struct input_mt_slot {
> * @trkid: stores MT tracking ID for the next contact
> * @num_slots: number of MT slots the device uses
> * @flags: input_mt operation flags
> + * @frame: increases every time input_mt_sync_frame() is called
> * @slots: array of slots holding current values of tracked contacts
> */
> struct input_mt {
> int trkid;
> int num_slots;
> unsigned int flags;
> + unsigned int frame;
> struct input_mt_slot slots[];
> };
>
> @@ -79,4 +86,6 @@ void input_mt_report_slot_state(struct input_dev *dev,
> void input_mt_report_finger_count(struct input_dev *dev, int count);
> void input_mt_report_pointer_emulation(struct input_dev *dev, bool use_count);
>
> +void input_mt_sync_frame(struct input_dev *dev);
> +
> #endif
> --
> 1.7.11.4
>
> --
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