On Thu, 2011-04-14 at 17:37 -0400, Nat Gurumoorthy wrote:
> 01 - Changes to it87 watchdog driver to use "request_muxed_region"
> Serialize access to the hardware by using "request_muxed_region" macro defined
> by Alan Cox. Call to this macro will hold off the requestor if the resource is
> currently busy. The first call to request_muxed_region will attempt 10 times
> to reserve the region before it gives up. This will typically get called from
> the driver init routines. If this succeeds then subsequent calls wait forever
> for the resource to be available.
>
> The use of the above macro makes it possible to get rid of
> spinlocks in it8712f_wdt.c and it87_wdt.c watchdog drivers.
> This also greatly simplifies the implementation of it87_wdt.c driver.
>
> Signed-off-by: Nat Gurumoorthy <natg@xxxxxxxxxx>
> ---
>
> diff --git a/drivers/watchdog/it8712f_wdt.c b/drivers/watchdog/it8712f_wdt.c
> index 6143f52..8bf2524 100644
> --- a/drivers/watchdog/it8712f_wdt.c
> +++ b/drivers/watchdog/it8712f_wdt.c
> @@ -51,7 +51,6 @@ MODULE_PARM_DESC(nowayout, "Disable watchdog shutdown on close");
>
> static unsigned long wdt_open;
> static unsigned expect_close;
> -static spinlock_t io_lock;
> static unsigned char revision;
>
> /* Dog Food address - We use the game port address */
> @@ -121,9 +120,46 @@ static inline void superio_select(int ldn)
> outb(ldn, VAL);
> }
>
> -static inline void superio_enter(void)
> +static inline int
> +try_superio_enter(void)
> {
> - spin_lock(&io_lock);
> + int num_tries = 10;
> + /*
> + * Try to reserve REG and REG + 1 for exclusive access.
> + * Give up after 10 attempts.
> + */
> + while (num_tries--) {
> + if (!request_muxed_region(REG, 2, NAME)) {
> + if (num_tries)
> + continue;
> +
> + /*
> + * Someone is holding the region. Give up.
> + */
> + pr_err("I/O address 0x%04x already in use\n", REG);
> + return -EBUSY;
> + }
> +
> + break;
> + }
> +
This is way too complicated. Just return an error if
request_muxed_region fails, like all other callers of
request_muxed_region do.
Guenter
_______________________________________________
lm-sensors mailing list
lm-sensors@xxxxxxxxxxxxxx
http://lists.lm-sensors.org/mailman/listinfo/lm-sensors
