Hi Pavel,
On Sat, Jul 11, 2015 at 01:47:46AM +0200, Pavel Rojtberg wrote:
> From: Pavel Rojtberg <rojtberg@xxxxxxxxx>
>
> The pad_nr should be consistent after disconnecting/ reconnecting a
> xbox360 controllers.
> Use a bitmask to track connected pads - this way we can re-assign freed
> up pad numbers.
>
> Consider the following case:
> 1. pad A is connected and gets pad_nr = 0
> 2. pad B is connected and gets pad_nr = 1
> 3. pad A is disconnected
> 4. pad A is connected again
>
> using the bitmask controller A now correctly gets pad_nr = 0 again.
And what happens if I pull both out and plug B first? Why do we care
about this? If we really want stable numbering maybe it should be driven
from userspace based on connection path?
>
> Note: this sets a limit of 32 simultaneous connected xbox360
> controllers. However this should be tolerable.
>
> Signed-off-by: Pavel Rojtberg <rojtberg@xxxxxxxxx>
> ---
> drivers/input/joystick/xpad.c | 20 +++++++++++++++-----
> 1 file changed, 15 insertions(+), 5 deletions(-)
>
> diff --git a/drivers/input/joystick/xpad.c b/drivers/input/joystick/xpad.c
> index a9ff4c2..e28a9c1 100644
> --- a/drivers/input/joystick/xpad.c
> +++ b/drivers/input/joystick/xpad.c
> @@ -346,6 +346,8 @@ struct usb_xpad {
> struct work_struct work; /* init/remove device from callback */
> };
>
> +static unsigned long xpad_pad_seq;
> +
> static int xpad_init_input(struct usb_xpad *xpad);
> static void xpad_deinit_input(struct usb_xpad *xpad);
>
> @@ -940,6 +942,12 @@ static void xpad_send_led_command(struct usb_xpad *xpad, int command)
> */
> static void xpad_identify_controller(struct usb_xpad *xpad)
> {
> + if (xpad->xtype != XTYPE_XBOX360 && xpad->xtype != XTYPE_XBOX360W)
> + return;
> +
> + xpad->pad_nr = find_first_zero_bit(&xpad_pad_seq, 32);
> + set_bit(xpad->pad_nr, &xpad_pad_seq);
> +
This is racy. If we really want it you might consider idr/ida.
Thanks.
--
Dmitry
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