scsi: ufs: change msleep to usleep_range

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>
Acked-by: Stanley Chu <stanley.chu@mediatek.com>
Reviewed-by: Avri Altman <avri.altman@wdc.com>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>

diff --git a/drivers/scsi/ufs/ufshcd.c b/drivers/scsi/ufs/ufshcd.c
index 3804a70..a383d0f 100644 (file)
--- a/drivers/scsi/ufs/ufshcd.c
+++ b/drivers/scsi/ufs/ufshcd.c
@@ -4226,12 +4226,6 @@ 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);
@@ -4254,7 +4248,7 @@ 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;
@@ -4266,7 +4260,7 @@ 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 */