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Subject[PATCH v1] scsi: ufs: change msleep to usleep_range
Date
From: Bean Huo <beanhuo@micron.com>

This patch is to change msleep() to usleep_range() based on
Documentation/timers/timers-howto.txt. It suggests using
usleep_range() for small msec(1ms - 20ms) since msleep()
will often sleep longer than desired value.

After changing, booting time will be 5ms-10ms faster than before.
I tested this change on two different platforms, one has 5ms faster,
another one is about 10ms. I think this is different on different
platform.

Actually, from UFS host side, 1ms-5ms delay is already sufficient for
its initialization of the local UIC layer.

Fixes: 7a3e97b0dc4b ([SCSI] ufshcd: UFS Host controller driver)
Signed-off-by: Bean Huo <beanhuo@micron.com>
---
drivers/scsi/ufs/ufshcd.c | 10 ++--------
1 file changed, 2 insertions(+), 8 deletions(-)

diff --git a/drivers/scsi/ufs/ufshcd.c b/drivers/scsi/ufs/ufshcd.c
index a208589426b1..21f7b3b8026c 100644
--- a/drivers/scsi/ufs/ufshcd.c
+++ b/drivers/scsi/ufs/ufshcd.c
@@ -4213,12 +4213,6 @@ static int ufshcd_hba_execute_hce(struct ufs_hba *hba)
{
int retry;

- /*
- * msleep of 1 and 5 used in this function might result in msleep(20),
- * but it was necessary to send the UFS FPGA to reset mode during
- * development and testing of this driver. msleep can be changed to
- * mdelay and retry count can be reduced based on the controller.
- */
if (!ufshcd_is_hba_active(hba))
/* change controller state to "reset state" */
ufshcd_hba_stop(hba, true);
@@ -4241,7 +4235,7 @@ static int ufshcd_hba_execute_hce(struct ufs_hba *hba)
* instruction might be read back.
* This delay can be changed based on the controller.
*/
- msleep(1);
+ usleep_range(1000, 1100);

/* wait for the host controller to complete initialization */
retry = 10;
@@ -4253,7 +4247,7 @@ static int ufshcd_hba_execute_hce(struct ufs_hba *hba)
"Controller enable failed\n");
return -EIO;
}
- msleep(5);
+ usleep_range(5000, 5100);
}

/* enable UIC related interrupts */
--
2.7.4
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