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>
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@ -50,6 +50,7 @@
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#include <linux/blkdev.h>
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#include <linux/blkdev.h>
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#include <linux/delay.h>
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#include <linux/delay.h>
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#include <linux/timer.h>
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#include <linux/timer.h>
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#include <linux/time.h>
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#include <linux/interrupt.h>
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#include <linux/interrupt.h>
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#include <linux/completion.h>
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#include <linux/completion.h>
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#include <linux/suspend.h>
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#include <linux/suspend.h>
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@ -6704,7 +6705,12 @@ void ata_msleep(struct ata_port *ap, unsigned int msecs)
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if (owns_eh)
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if (owns_eh)
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ata_eh_release(ap);
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ata_eh_release(ap);
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msleep(msecs);
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if (msecs < 20) {
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unsigned long usecs = msecs * USEC_PER_MSEC;
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usleep_range(usecs, usecs + 50);
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} else {
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msleep(msecs);
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}
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if (owns_eh)
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if (owns_eh)
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ata_eh_acquire(ap);
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ata_eh_acquire(ap);
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