Re: [PATCH 4/7] Input: ALPS - Remove assumptions about packet size

Chase Douglas
2011-10-30T15:36:25Z

On 10/26/2011 05:14 PM, Seth Forshee wrote:
> In preparation for version 4 protocol support, which has 8-byte
> data packets, remove all hard-coded assumptions about packet size
> and use psmouse->pktsize instead.
>
> Signed-off-by: Seth Forshee <seth.forshee@canonical.com>
> ---
> drivers/input/mouse/alps.c | 27 ++++++++++++++++++---------
> 1 files changed, 18 insertions(+), 9 deletions(-)
>
> diff --git a/drivers/input/mouse/alps.c b/drivers/input/mouse/alps.c
> index 572cb21..14d1f64 100644
> --- a/drivers/input/mouse/alps.c
> +++ b/drivers/input/mouse/alps.c
> @@ -315,7 +315,7 @@ static void alps_flush_packet(unsigned long data)
>
> serio_pause_rx(psmouse->ps2dev.serio);
>
> - if (psmouse->pktcnt == 6) {
> + if (psmouse->pktcnt == psmouse->pktsize) {
>
> /*
> * We did not any more data in reasonable amount of time.
> @@ -365,15 +365,15 @@ static psmouse_ret_t alps_process_byte(struct psmouse *psmouse)
> return PSMOUSE_BAD_DATA;
> }
>
> - /* Bytes 2 - 6 should have 0 in the highest bit */
> - if (psmouse->pktcnt >= 2 && psmouse->pktcnt <= 6 &&
> + /* Bytes 2 - pktsize should have 0 in the highest bit */
> + if (psmouse->pktcnt >= 2 && psmouse->pktcnt <= psmouse->pktsize &&
> (psmouse->packet[psmouse->pktcnt - 1] & 0x80)) {
> dbg("refusing packet[%i] = %x\n",
> psmouse->pktcnt - 1, psmouse->packet[psmouse->pktcnt - 1]);
> return PSMOUSE_BAD_DATA;
> }
>
> - if (psmouse->pktcnt == 6) {
> + if (psmouse->pktcnt == psmouse->pktsize) {
> alps_process_packet(psmouse);
> return PSMOUSE_FULL_PACKET;
> }
> @@ -531,8 +531,13 @@ static int alps_tap_mode(struct psmouse *psmouse, int enable)
> static int alps_poll(struct psmouse *psmouse)
> {
> struct alps_data *priv = psmouse->private;
> - unsigned char buf[6];
> + unsigned char *buf;
> bool poll_failed;
> + int ret = -1;
> +
> + buf = kmalloc(psmouse->pktsize, GFP_KERNEL);
> + if (!buf)
> + return -1;

Can we preallocate a buffer somewhere instead of allocating every time
we enter the function? If we know the maximum packet size we could
allocate on the stack instead.

-- Chase