linux-kernel - Re: [PATCH v3 09/13] HID: hid-multitouch: add MT_QUIRK_IGNORE

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Message-ID: <20121113162531.GA669@polaris.bitmath.org>
Date:	Tue, 13 Nov 2012 17:25:31 +0100
From:	"Henrik Rydberg" <rydberg@...omail.se>
To:	Benjamin Tissoires <benjamin.tissoires@...il.com>
Cc:	Dmitry Torokhov <dmitry.torokhov@...il.com>,
	Jiri Kosina <jkosina@...e.cz>,
	Stephane Chatty <chatty@...c.fr>, linux-input@...r.kernel.org,
	linux-kernel@...r.kernel.org
Subject: Re: [PATCH v3 09/13] HID: hid-multitouch: add
 MT_QUIRK_IGNORE_DUPLICATES

Hi Benjamin,

> this prevents a device to reuse contact id 0 several time when
> sending garbage values to complete the report.

This quirk allows a device to reuse a contact id when sending garbage
inactive contacts at the end of a report.

> 
> Signed-off-by: Benjamin Tissoires <benjamin.tissoires@...il.com>
> ---
>  drivers/hid/hid-multitouch.c | 6 ++++++
>  include/linux/input/mt.h     | 6 ++++++
>  2 files changed, 12 insertions(+)
> 
> diff --git a/drivers/hid/hid-multitouch.c b/drivers/hid/hid-multitouch.c
> index 2352770..351c814 100644
> --- a/drivers/hid/hid-multitouch.c
> +++ b/drivers/hid/hid-multitouch.c
> @@ -52,6 +52,7 @@ MODULE_LICENSE("GPL");
>  #define MT_QUIRK_VALID_IS_CONFIDENCE	(1 << 6)
>  #define MT_QUIRK_SLOT_IS_CONTACTID_MINUS_ONE	(1 << 8)
>  #define MT_QUIRK_NO_AREA		(1 << 9)
> +#define MT_QUIRK_IGNORE_DUPLICATES	(1 << 10)
>  
>  struct mt_slot {
>  	__s32 x, y, cx, cy, p, w, h;
> @@ -510,6 +511,11 @@ static void mt_complete_slot(struct mt_device *td, struct input_dev *input)
>  		if (slotnum < 0 || slotnum >= td->maxcontacts)
>  			return;
>  
> +		if (td->mtclass.quirks & MT_QUIRK_IGNORE_DUPLICATES &&

Don't like parenthesis, i see :-)

> +		    input_mt_is_active(&input->mt->slots[slotnum]) &&
> +		    input_mt_is_used(input->mt, &input->mt->slots[slotnum]))
> +				return;
> +

It init_mt_slots failed earlier (no checks), input->mt can be NULL
here. Also, a local variable instead of repetition would be nice.

>  		input_mt_slot(input, slotnum);
>  		input_mt_report_slot_state(input, MT_TOOL_FINGER,
>  			s->touch_state);
> diff --git a/include/linux/input/mt.h b/include/linux/input/mt.h
> index cc5cca7..2e86bd0 100644
> --- a/include/linux/input/mt.h
> +++ b/include/linux/input/mt.h
> @@ -69,6 +69,12 @@ static inline bool input_mt_is_active(const struct input_mt_slot *slot)
>  	return input_mt_get_value(slot, ABS_MT_TRACKING_ID) >= 0;
>  }
>  
> +static inline bool input_mt_is_used(const struct input_mt *mt,
> +				    const struct input_mt_slot *slot)
> +{
> +	return slot->frame == mt->frame;
> +}
> +

This is ok, although I would prefer to also change input-mt.c to use
this helper function. Possibly that turns this hunk into a separate patch.

>  int input_mt_init_slots(struct input_dev *dev, unsigned int num_slots,
>  			unsigned int flags);
>  void input_mt_destroy_slots(struct input_dev *dev);
> -- 
> 1.7.11.7
> 

Thanks,
Henrik
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