linux-kernel - Re: [PATCH 02/19] Input: Improve the events-per-packet estimate

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Date:	Tue, 14 Aug 2012 12:32:21 -0700
From:	Ping Cheng <pinglinux@...il.com>
To:	Henrik Rydberg <rydberg@...omail.se>
Cc:	Dmitry Torokhov <dmitry.torokhov@...il.com>,
	Jiri Kosina <jkosina@...e.cz>, linux-input@...r.kernel.org,
	linux-kernel@...r.kernel.org
Subject: Re: [PATCH 02/19] Input: Improve the events-per-packet estimate

On Sun, Aug 12, 2012 at 2:42 PM, Henrik Rydberg <rydberg@...omail.se> wrote:
> Many MT devices send a number of keys along with the mt information.
> This patch makes sure that there is room for them in the packet
> buffer.
>
> Signed-off-by: Henrik Rydberg <rydberg@...omail.se>
> ---
>  drivers/input/input.c | 10 +++++++---
>  1 file changed, 7 insertions(+), 3 deletions(-)
>
> diff --git a/drivers/input/input.c b/drivers/input/input.c
> index 6e90705..8ebf116 100644
> --- a/drivers/input/input.c
> +++ b/drivers/input/input.c
> @@ -1777,6 +1777,9 @@ static unsigned int input_estimate_events_per_packet(struct input_dev *dev)
>                 if (test_bit(i, dev->relbit))
>                         events++;
>
> +       /* Make room for KEY and MSC events */
> +       events += 7;

Hi Henrik,

It is nice to get rid of the redundant pieces and to incorporate
common functions. Thank you.

I have a question about the code above though.  Why do we use 7
instead of going through the keys like:

	for (i = 0; i < KEY_MAX; i++)
		if (test_bit(i, dev->keybit))
			events++;

Ping

> +
>         return events;
>  }
>
> @@ -1815,6 +1818,7 @@ int input_register_device(struct input_dev *dev)
>  {
>         static atomic_t input_no = ATOMIC_INIT(0);
>         struct input_handler *handler;
> +       unsigned int packet_size;
>         const char *path;
>         int error;
>
> @@ -1827,9 +1831,9 @@ int input_register_device(struct input_dev *dev)
>         /* Make sure that bitmasks not mentioned in dev->evbit are clean. */
>         input_cleanse_bitmasks(dev);
>
> -       if (!dev->hint_events_per_packet)
> -               dev->hint_events_per_packet =
> -                               input_estimate_events_per_packet(dev);
> +       packet_size = input_estimate_events_per_packet(dev);
> +       if (dev->hint_events_per_packet < packet_size)
> +               dev->hint_events_per_packet = packet_size;
>
>         /*
>          * If delay and period are pre-set by the driver, then autorepeating
> --
> 1.7.11.4
>
> --
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