From: "Henrik Rydberg" <rydberg@euromail.se>
Date: Fri, 25 Mar 2011 09:20:30 +0100
To: Jeff Brown <jeffbrown@android.com>
Cc: linux-input@vger.kernel.org, linux-kernel@vger.kernel.org,
        Jeff Brown <jeffbrown@google.com>
Subject: Re: [PATCH 1/4] input: Set default events per packet.
Message-ID: <20110325082030.GB5664@polaris.bitmath.org>
References: <1300842244-42723-1-git-send-email-jeffbrown@android.com>
 <1300842244-42723-2-git-send-email-jeffbrown@android.com>
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Hi Jeff,

> Calculate a default based on the number of ABS axes, REL axes,
> and MT slots for the device during input device registration.
> 
> Signed-off-by: jeffbrown@android.com
> ---
>  drivers/input/input.c |   46 ++++++++++++++++++++++++++++++++++++++++++++++
>  1 files changed, 46 insertions(+), 0 deletions(-)
> 
> diff --git a/drivers/input/input.c b/drivers/input/input.c
> index d6e8bd8..c27292b 100644
> --- a/drivers/input/input.c
> +++ b/drivers/input/input.c
> @@ -1746,6 +1746,49 @@ void input_set_capability(struct input_dev *dev, unsigned int type, unsigned int
>  }
>  EXPORT_SYMBOL(input_set_capability);
>  
> +static inline bool is_mt_axis(int axis)
> +{
> +	return axis == ABS_MT_SLOT ||
> +		(axis >= ABS_MT_FIRST && axis <= ABS_MT_LAST);
> +}

It would be great to get this inline into input/mt.h instead.

> +static void input_set_default_events_per_packet(struct input_dev *dev)
> +{
> +	int mt_slots;
> +	int i;
> +	int events;
> +
> +	if (dev->hint_events_per_packet)
> +		return;
> +
> +	if (dev->mtsize)
> +		mt_slots = dev->mtsize;
> +	else if (test_bit(ABS_MT_TRACKING_ID, dev->absbit))
> +		mt_slots = dev->absinfo[ABS_MT_TRACKING_ID].maximum -
> +			dev->absinfo[ABS_MT_TRACKING_ID].minimum + 1;

This one is a bit iffy - the tracking id is not limited like this in
mainline, looks like android usage. A test againts some arbitrary max
should do it.

> +	else if (test_bit(ABS_MT_POSITION_X, dev->absbit))
> +		mt_slots = 2;
> +	else
> +		mt_slots = 0;
> +
> +	events = mt_slots + 1; /* count SYN_MT_REPORT and SYN_REPORT */
> +
> +	for (i = 0; i < ABS_CNT; i++) {
> +		if (test_bit(i, dev->absbit)) {
> +			if (is_mt_axis(i))
> +				events += mt_slots;
> +			else
> +				events++;
> +		}
> +	}
> +
> +	for (i = 0; i < REL_CNT; i++)
> +		if (test_bit(i, dev->relbit))
> +			events++;
> +
> +	input_set_events_per_packet(dev, events);
> +}
> +
>  #define INPUT_CLEANSE_BITMASK(dev, type, bits)				\
>  	do {								\
>  		if (!test_bit(EV_##type, dev->evbit))			\
> @@ -1784,6 +1827,9 @@ int input_register_device(struct input_dev *dev)
>  	const char *path;
>  	int error;
>  
> +	/* Use a larger default input buffer for MT devices */
> +	input_set_default_events_per_packet(dev);
> +
>  	/* Every input device generates EV_SYN/SYN_REPORT events. */
>  	__set_bit(EV_SYN, dev->evbit);
>  
> -- 
> 1.7.0.4

Thanks,
Henrik
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