linux-kernel - [PATCH v2] ufs: poll HCS.UCRDY before issuing a UIC command

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Message-Id: <1684208012-114324-1-git-send-email-kwmad.kim@samsung.com>
Date:   Tue, 16 May 2023 12:33:32 +0900
From:   Kiwoong Kim <kwmad.kim@...sung.com>
To:     linux-scsi@...r.kernel.org, linux-kernel@...r.kernel.org,
        alim.akhtar@...sung.com, avri.altman@....com, bvanassche@....org,
        jejb@...ux.ibm.com, martin.petersen@...cle.com, beanhuo@...ron.com,
        adrian.hunter@...el.com, sc.suh@...sung.com, hy50.seo@...sung.com,
        sh425.lee@...sung.com, kwangwon.min@...sung.com
Cc:     Kiwoong Kim <kwmad.kim@...sung.com>
Subject: [PATCH v2] ufs: poll HCS.UCRDY before issuing a UIC command

v1 -> v2: replace usleep_range with udelay
because it's a sleepable period.

With auto hibern8 enabled, UIC could be working
for a while to process a hibern8 operation and HCI
reports UIC not ready for a short term through HCS.UCRDY.
And UFS driver can't recognize the operation.
UFSHCI spec specifies UCRDY like this:
whether the host controller is ready to process UIC COMMAND

The 'ready' could be seen as many different meanings. If the meaning
includes not processing any request from HCI, processing a hibern8
operation can be 'not ready'. In this situation, the driver needs to
wait until the operations is completed.

Signed-off-by: Kiwoong Kim <kwmad.kim@...sung.com>
---
 drivers/ufs/core/ufshcd.c | 13 ++++++++++++-
 1 file changed, 12 insertions(+), 1 deletion(-)

diff --git a/drivers/ufs/core/ufshcd.c b/drivers/ufs/core/ufshcd.c
index 9434328..5f6819a 100644
--- a/drivers/ufs/core/ufshcd.c
+++ b/drivers/ufs/core/ufshcd.c
@@ -2365,7 +2365,18 @@ static inline int ufshcd_hba_capabilities(struct ufs_hba *hba)
  */
 static inline bool ufshcd_ready_for_uic_cmd(struct ufs_hba *hba)
 {
-	return ufshcd_readl(hba, REG_CONTROLLER_STATUS) & UIC_COMMAND_READY;
+	ktime_t timeout = ktime_add_ms(ktime_get(), UIC_CMD_TIMEOUT);
+	u32 val = 0;
+
+	do {
+		val = ufshcd_readl(hba, REG_CONTROLLER_STATUS) &
+			UIC_COMMAND_READY;
+		if (val)
+			break;
+		udelay(500);
+	} while (ktime_before(ktime_get(), timeout));
+
+	return val ? true : false;
 }
 
 /**
-- 
2.7.4