Re: [lm-sensors] [PATCH v5 1/2] Use "request_muxed_region" in it87watchdog drivers

From: Hans de Goede
Date: Wed Apr 13 2011 - 02:51:42 EST


On 04/12/2011 10:49 PM, 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 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..51bfbc0 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 */
@@ -123,7 +122,11 @@ static inline void superio_select(int ldn)

static inline void superio_enter(void)
- spin_lock(&io_lock);
+ /*
+ * Reserve REG and REG + 1 for exclusive access.
+ */
+ (void) request_muxed_region(REG, 2, NAME);

You shouldn't (void) this, there is a reason you get a warning
otherwise! request_muxed_region can still fail if some other driver
has done a none muxed request_region on the same region, and in that
case you should not continue with accessing the io-ports.


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