From: Avri Altman <Avri.Altman@wdc.com>
To: Stanley Chu <stanley.chu@mediatek.com>,
"linux-scsi@vger.kernel.org" <linux-scsi@vger.kernel.org>,
"martin.petersen@oracle.com" <martin.petersen@oracle.com>,
"alim.akhtar@samsung.com" <alim.akhtar@samsung.com>,
"jejb@linux.ibm.com" <jejb@linux.ibm.com>
Cc: "pengshun.zhao@mediatek.com" <pengshun.zhao@mediatek.com>,
"bvanassche@acm.org" <bvanassche@acm.org>,
"andy.teng@mediatek.com" <andy.teng@mediatek.com>,
"cc.chou@mediatek.com" <cc.chou@mediatek.com>,
"chun-hung.wu@mediatek.com" <chun-hung.wu@mediatek.com>,
"kuohong.wang@mediatek.com" <kuohong.wang@mediatek.com>,
"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
"cang@codeaurora.org" <cang@codeaurora.org>,
"linux-mediatek@lists.infradead.org"
<linux-mediatek@lists.infradead.org>,
"peter.wang@mediatek.com" <peter.wang@mediatek.com>,
"matthias.bgg@gmail.com" <matthias.bgg@gmail.com>,
"beanhuo@micron.com" <beanhuo@micron.com>,
"chaotian.jing@mediatek.com" <chaotian.jing@mediatek.com>,
"linux-arm-kernel@lists.infradead.org"
<linux-arm-kernel@lists.infradead.org>,
"asutoshd@codeaurora.org" <asutoshd@codeaurora.org>
Subject: RE: [PATCH v2 1/5] scsi: ufs-mediatek: Fix imprecise waiting time for ref-clk control
Date: Sun, 31 May 2020 07:10:23 +0000 [thread overview]
Message-ID: <SN6PR04MB464015BDF84DF7A9779BEB41FC8D0@SN6PR04MB4640.namprd04.prod.outlook.com> (raw)
In-Reply-To: <20200529092310.1106-2-stanley.chu@mediatek.com>
>
> Currently ref-clk control timeout is implemented by Jiffies. However
> jiffies is not accurate enough thus "false timeout" may happen.
>
> Use more accurate delay mechanism instead, for example, ktime.
>
> Signed-off-by: Stanley Chu <stanley.chu@mediatek.com>
> Reviewed-by: Andy Teng <andy.teng@mediatek.com>
Reviewed-by: Avri Altman <avri.altman@wdc.com>
> ---
> drivers/scsi/ufs/ufs-mediatek.c | 7 ++++---
> drivers/scsi/ufs/ufs-mediatek.h | 2 +-
> 2 files changed, 5 insertions(+), 4 deletions(-)
>
> diff --git a/drivers/scsi/ufs/ufs-mediatek.c b/drivers/scsi/ufs/ufs-mediatek.c
> index d56ce8d97d4e..523ee5573921 100644
> --- a/drivers/scsi/ufs/ufs-mediatek.c
> +++ b/drivers/scsi/ufs/ufs-mediatek.c
> @@ -120,7 +120,7 @@ static int ufs_mtk_setup_ref_clk(struct ufs_hba *hba,
> bool on)
> {
> struct ufs_mtk_host *host = ufshcd_get_variant(hba);
> struct arm_smccc_res res;
> - unsigned long timeout;
> + ktime_t timeout, time_checked;
> u32 value;
>
> if (host->ref_clk_enabled == on)
> @@ -135,8 +135,9 @@ static int ufs_mtk_setup_ref_clk(struct ufs_hba *hba,
> bool on)
> }
>
> /* Wait for ack */
> - timeout = jiffies + msecs_to_jiffies(REFCLK_REQ_TIMEOUT_MS);
> + timeout = ktime_add_us(ktime_get(), REFCLK_REQ_TIMEOUT_US);
> do {
> + time_checked = ktime_get();
> value = ufshcd_readl(hba, REG_UFS_REFCLK_CTRL);
>
> /* Wait until ack bit equals to req bit */
> @@ -144,7 +145,7 @@ static int ufs_mtk_setup_ref_clk(struct ufs_hba *hba,
> bool on)
> goto out;
>
> usleep_range(100, 200);
> - } while (time_before(jiffies, timeout));
> + } while (ktime_before(time_checked, timeout));
Nit: you could get rid of time_checked if you would use ktime_compare(ktime_get(), timeout) > 0
Thanks,
Avri
>
> dev_err(hba->dev, "missing ack of refclk req, reg: 0x%x\n", value);
>
> diff --git a/drivers/scsi/ufs/ufs-mediatek.h b/drivers/scsi/ufs/ufs-mediatek.h
> index 5bbd3e9cbae2..fc42dcbfd800 100644
> --- a/drivers/scsi/ufs/ufs-mediatek.h
> +++ b/drivers/scsi/ufs/ufs-mediatek.h
> @@ -28,7 +28,7 @@
> #define REFCLK_REQUEST BIT(0)
> #define REFCLK_ACK BIT(1)
>
> -#define REFCLK_REQ_TIMEOUT_MS 3
> +#define REFCLK_REQ_TIMEOUT_US 3000
>
> /*
> * Vendor specific pre-defined parameters
> --
> 2.18.0
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next prev parent reply other threads:[~2020-05-31 7:10 UTC|newest]
Thread overview: 8+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-05-29 9:23 [PATCH v2 0/5] scsi: ufs-mediatek: Fix clk-gating and introduce low-power mode for vccq2 Stanley Chu
2020-05-29 9:23 ` [PATCH v2 1/5] scsi: ufs-mediatek: Fix imprecise waiting time for ref-clk control Stanley Chu
2020-05-31 7:10 ` Avri Altman [this message]
2020-05-31 13:45 ` Stanley Chu
2020-05-29 9:23 ` [PATCH v2 2/5] scsi: ufs-mediatek: Do not gate clocks if auto-hibern8 is not entered yet Stanley Chu
2020-05-29 9:23 ` [PATCH v2 3/5] scsi: ufs-mediatek: Introduce low-power mode for device power supply Stanley Chu
2020-05-29 9:23 ` [PATCH v2 4/5] scsi: ufs-mediatek: Fix unbalanced clock on/off Stanley Chu
2020-05-29 9:23 ` [PATCH v2 5/5] scsi: ufs-mediatek: Allow unbound mphy Stanley Chu
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