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authorAnil Veliyankara Madam <aveliyan@cisco.com>2016-01-07 21:18:52 -0800
committerTejun Heo <tj@kernel.org>2016-01-08 10:36:57 -0500
commit848c3920866fdb7b8b353408348df7929306e9be (patch)
treecbb86365742718165a97a1df062677b35347f072 /drivers/ata
parent427cc61a4486fa80eccaad2bdfcc50cfd1b46625 (diff)
downloadlinux-848c3920866fdb7b8b353408348df7929306e9be.tar.bz2
drivers: libata-core: Use usleep_range() instead of msleep() for short sleeps (<20 ms)
Since msleep() may sleep longer than intended time for values less than 20ms, this patch allows the use of usleep_range for waits less that 20ms. usleep_range is a finer precision implementation of msleep and is designed to be a drop-in replacement for udelay where a precise sleep/busy-wait is unnecessary. More details can be found at http://lkml.org/lkml/2007/8/3/250 and in Documentation/timers/timers-howto.txt. This change has been done to improve the performace in PIO6 mode which is used by viking flash. Cc: xe-kernel@external.cisco.com Signed-off-by: Anil Veliyankara Madam <aveliyan@cisco.com> Signed-off-by: Shikha Jain <shikjain@cisco.com> Signed-off-by: Tejun Heo <tj@kernel.org>
Diffstat (limited to 'drivers/ata')
-rw-r--r--drivers/ata/libata-core.c8
1 files changed, 7 insertions, 1 deletions
diff --git a/drivers/ata/libata-core.c b/drivers/ata/libata-core.c
index 60e368610c74..f5ae6f43b659 100644
--- a/drivers/ata/libata-core.c
+++ b/drivers/ata/libata-core.c
@@ -50,6 +50,7 @@
#include <linux/blkdev.h>
#include <linux/delay.h>
#include <linux/timer.h>
+#include <linux/time.h>
#include <linux/interrupt.h>
#include <linux/completion.h>
#include <linux/suspend.h>
@@ -6704,7 +6705,12 @@ void ata_msleep(struct ata_port *ap, unsigned int msecs)
if (owns_eh)
ata_eh_release(ap);
- msleep(msecs);
+ if (msecs < 20) {
+ unsigned long usecs = msecs * USEC_PER_MSEC;
+ usleep_range(usecs, usecs + 50);
+ } else {
+ msleep(msecs);
+ }
if (owns_eh)
ata_eh_acquire(ap);