[PATCH] ieee1394: fix calculation of csr->expire
This variant of calculate_expire() is more correct and easier to read.
Signed-off-by: Stefan Richter <stefanr@s5r6.in-berlin.de>
Signed-off-by: Ben Collins <bcollins@ubuntu.com>
diff --git a/drivers/ieee1394/csr.c b/drivers/ieee1394/csr.c
index 149573d..ab0c80f 100644
--- a/drivers/ieee1394/csr.c
+++ b/drivers/ieee1394/csr.c
@@ -17,11 +17,13 @@
*
*/
-#include <linux/string.h>
+#include <linux/jiffies.h>
+#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/moduleparam.h>
#include <linux/param.h>
#include <linux/spinlock.h>
+#include <linux/string.h>
#include "csr1212.h"
#include "ieee1394_types.h"
@@ -149,31 +151,18 @@
/*
* HI == seconds (bits 0:2)
- * LO == fraction units of 1/8000 of a second, as per 1394 (bits 19:31)
+ * LO == fractions of a second in units of 125usec (bits 19:31)
*
- * Convert to units and then to HZ, for comparison to jiffies.
- *
- * By default this will end up being 800 units, or 100ms (125usec per
- * unit).
- *
- * NOTE: The spec says 1/8000, but also says we can compute based on 1/8192
- * like CSR specifies. Should make our math less complex.
+ * Convert SPLIT_TIMEOUT to jiffies.
+ * The default and minimum as per 1394a-2000 clause 8.3.2.2.6 is 100ms.
*/
static inline void calculate_expire(struct csr_control *csr)
{
- unsigned long units;
+ unsigned long usecs =
+ (csr->split_timeout_hi & 0x07) * USEC_PER_SEC +
+ (csr->split_timeout_lo >> 19) * 125L;
- /* Take the seconds, and convert to units */
- units = (unsigned long)(csr->split_timeout_hi & 0x07) << 13;
-
- /* Add in the fractional units */
- units += (unsigned long)(csr->split_timeout_lo >> 19);
-
- /* Convert to jiffies */
- csr->expire = (unsigned long)(units * HZ) >> 13UL;
-
- /* Just to keep from rounding low */
- csr->expire++;
+ csr->expire = usecs_to_jiffies(usecs > 100000L ? usecs : 100000L);
HPSB_VERBOSE("CSR: setting expire to %lu, HZ=%u", csr->expire, HZ);
}