hwmon: applesmc: prolong status wait

The time to wait for a status change while reading or writing to the SMC
ports is a balance between read reliability and system performance.  The
current setting yields rougly three errors in a thousand when
simultaneously reading three different temperature values on a Macbook
Air.  This patch increases the setting to a value yielding roughly one
error in ten thousand, with no noticable system performance degradation.

Signed-off-by: Henrik Rydberg <rydberg@euromail.se>
Cc: Nicolas Boichat <nicolas@boichat.ch>
Cc: Riki Oktarianto <rkoktarianto@gmail.com>
Cc: Mark M. Hoffman <mhoffman@lightlink.com>
Cc: Jean Delvare <khali@linux-fr.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

diff --git a/drivers/hwmon/applesmc.c b/drivers/hwmon/applesmc.c
index d5bd0cadbf31ac073e8017b81ced7ffc890bc0da..9a43c4b60ea92f73cc966965f70261a1fb71b078 100644 (file)
--- a/drivers/hwmon/applesmc.c
+++ b/drivers/hwmon/applesmc.c
@@ -163,7 +163,7 @@ static unsigned int key_at_index;
 static struct workqueue_struct *applesmc_led_wq;
 
 /*
- * __wait_status - Wait up to 2ms for the status port to get a certain value
+ * __wait_status - Wait up to 10ms for the status port to get a certain value
  * (masked with 0x0f), returning zero if the value is obtained.  Callers must
  * hold applesmc_lock.
  */
@@ -173,7 +173,7 @@ static int __wait_status(u8 val)
 
        val = val & APPLESMC_STATUS_MASK;
 
-       for (i = 0; i < 200; i++) {
+       for (i = 0; i < 1000; i++) {
                if ((inb(APPLESMC_CMD_PORT) & APPLESMC_STATUS_MASK) == val) {
                        if (debug)
                                printk(KERN_DEBUG