From mboxrd@z Thu Jan 1 00:00:00 1970 From: Stanley Chu Subject: Re: [PATCH v1] scsi: ufs: change msleep to usleep_range Date: Tue, 16 Jul 2019 08:56:44 +0800 Message-ID: <1563238604.7235.5.camel@mtkswgap22> References: Mime-Version: 1.0 Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: Sender: linux-kernel-owner@vger.kernel.org To: "Bean Huo (beanhuo)" Cc: Alim Akhtar , Avri Altman , Pedro Sousa , "Martin K. Petersen" , "James E.J. Bottomley" , Evan Green , "linux-kernel@vger.kernel.org" , "linux-scsi@vger.kernel.org" List-Id: linux-scsi@vger.kernel.org Hi Bean, On Mon, 2019-07-15 at 11:21 +0000, Bean Huo (beanhuo) wrote: > From: Bean Huo > > 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 > --- > 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 Thanks, Stanley