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Commit 767e2644 authored by Stanley Chu's avatar Stanley Chu Committed by Greg Kroah-Hartman
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UPSTREAM: scsi: ufs-mediatek: Fix imprecise waiting time for ref-clk control 

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, i.e. ktime.

Link: https://lore.kernel.org/r/20200601104646.15436-2-stanley.chu@mediatek.com


Reviewed-by: default avatarAndy Teng <andy.teng@mediatek.com>
Reviewed-by: default avatarAvri Altman <avri.altman@wdc.com>
Signed-off-by: default avatarStanley Chu <stanley.chu@mediatek.com>
Signed-off-by: default avatarMartin K. Petersen <martin.petersen@oracle.com>

Bug: 151050916
(cherry picked from commit c0a18ee0ce78d7957ec1a53be35b1b3beba80668)
Change-Id: I08b6204db64bcf52d9f32ebdb23c168a8b1e88af
Signed-off-by: default avatarStanley Chu <stanley.chu@mediatek.com>
Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@google.com>
parent f05b5eba

drivers/scsi/ufs/ufs-mediatek.c

+4 −3
Original line number Diff line number Diff line
@@ -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));



	dev_err(hba->dev, "missing ack of refclk req, reg: 0x%x\n", value);

drivers/scsi/ufs/ufs-mediatek.h

+1 −1
Original line number Diff line number Diff line
@@ -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