From f0cbefe63c4347044fffebca24c03f3c6829f322 Mon Sep 17 00:00:00 2001 From: Stefan Richter Date: Mon, 3 Jul 2006 12:01:59 -0400 Subject: [PATCH] ieee1394: fix calculation of csr->expire This variant of calculate_expire() is more correct and easier to read. Signed-off-by: Stefan Richter Signed-off-by: Ben Collins --- drivers/ieee1394/csr.c | 31 ++++++++++--------------------- 1 file changed, 10 insertions(+), 21 deletions(-) diff --git a/drivers/ieee1394/csr.c b/drivers/ieee1394/csr.c index 149573db91c5..ab0c80f61b9d 100644 --- a/drivers/ieee1394/csr.c +++ b/drivers/ieee1394/csr.c @@ -17,11 +17,13 @@ * */ -#include +#include +#include #include #include #include #include +#include #include "csr1212.h" #include "ieee1394_types.h" @@ -149,31 +151,18 @@ static void host_reset(struct hpsb_host *host) /* * HI == seconds (bits 0:2) - * LO == fraction units of 1/8000 of a second, as per 1394 (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). + * LO == fractions of a second in units of 125usec (bits 19:31) * - * 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; - - /* 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; + unsigned long usecs = + (csr->split_timeout_hi & 0x07) * USEC_PER_SEC + + (csr->split_timeout_lo >> 19) * 125L; - /* 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); } -- cgit v1.2.3