2019-07-15 11:22:20

by Bean Huo (beanhuo)

[permalink] [raw]
Subject: [PATCH v1] scsi: ufs: change msleep to usleep_range

From: Bean Huo <[email protected]>

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 <[email protected]>
---
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


2019-07-16 00:58:46

by Stanley Chu

[permalink] [raw]
Subject: Re: [PATCH v1] scsi: ufs: change msleep to usleep_range

Hi Bean,

On Mon, 2019-07-15 at 11:21 +0000, Bean Huo (beanhuo) wrote:
> From: Bean Huo <[email protected]>
>
> 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 <[email protected]>
> ---
> 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 */

Acked-by: Stanley Chu <[email protected]>

Thanks,
Stanley



2019-07-16 06:57:05

by Avri Altman

[permalink] [raw]
Subject: RE: [PATCH v1] scsi: ufs: change msleep to usleep_range

>
> From: Bean Huo <[email protected]>
>
> 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 <[email protected]>
Reviewed-by: Avri Altman <[email protected]>

2019-07-17 02:51:23

by Martin K. Petersen

[permalink] [raw]
Subject: Re: [PATCH v1] scsi: ufs: change msleep to usleep_range


Bean,

> 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.

Applied to 5.4/scsi-queue, thanks!

--
Martin K. Petersen Oracle Linux Engineering