linux-kernel - [PATCH] scsi: ufs: core: skip UFS clkscale if host asynchronous scan in progress

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Message-Id: <20250508080503.3225174-1-quic_ziqichen@quicinc.com>
Date: Thu,  8 May 2025 16:05:00 +0800
From: Ziqi Chen <quic_ziqichen@...cinc.com>
To: quic_cang@...cinc.com, bvanassche@....org, mani@...nel.org,
        beanhuo@...ron.com, avri.altman@....com, junwoo80.lee@...sung.com,
        martin.petersen@...cle.com, quic_ziqichen@...cinc.com,
        quic_nguyenb@...cinc.com, quic_nitirawa@...cinc.com,
        quic_rampraka@...cinc.com, neil.armstrong@...aro.org,
        luca.weiss@...rphone.com, konrad.dybcio@....qualcomm.com,
        peter.wang@...iatek.com
Cc: linux-arm-msm@...r.kernel.org, linux-scsi@...r.kernel.org,
        Alim Akhtar <alim.akhtar@...sung.com>,
        "James E.J. Bottomley" <James.Bottomley@...senPartnership.com>,
        Manivannan Sadhasivam <manivannan.sadhasivam@...aro.org>,
        linux-kernel@...r.kernel.org (open list)
Subject: [PATCH] scsi: ufs: core: skip UFS clkscale if host asynchronous scan in progress

When preparing for UFS clock scaling, the UFS driver will quiesce all sdevs
queues on the UFS SCSI host tagset list and then unquiesce them when UFS
clock scaling unpreparing. If the UFS SCSI host async scan is in progress
at this time, some LUs may be added to the tagset list between UFS clkscale
prepare and unprepare. This can cause two issues:

1. During clock scaling, there may be IO requests issued through new added
queues that have not been quiesced, leading to task abort issue.

2. These new added queues that have not been quiesced will be unquiesced as
well when UFS clkscale is unprepared, resulting in warning prints.

Therefore, use the flag host->async_scan to check whether the host async
scan is in progress or not. Additionally, move ufshcd_devfreq_init() to
after ufshcd_add_lus() to ensure this flag already be set before starting
devfreq monitor.

Co-developed-by: Can Guo <quic_cang@...cinc.com>
Signed-off-by: Can Guo <quic_cang@...cinc.com>
Signed-off-by: Ziqi Chen <quic_ziqichen@...cinc.com>
---
 drivers/ufs/core/ufshcd.c | 16 +++++++++-------
 1 file changed, 9 insertions(+), 7 deletions(-)

diff --git a/drivers/ufs/core/ufshcd.c b/drivers/ufs/core/ufshcd.c
index 1c53ccf5a616..ce94fe4ab095 100644
--- a/drivers/ufs/core/ufshcd.c
+++ b/drivers/ufs/core/ufshcd.c
@@ -1207,6 +1207,9 @@ static bool ufshcd_is_devfreq_scaling_required(struct ufs_hba *hba,
 	if (list_empty(head))
 		return false;
 
+	if (hba->host->async_scan)
+		return false;
+
 	if (hba->use_pm_opp)
 		return freq != hba->clk_scaling.target_freq;
 
@@ -8746,13 +8749,6 @@ static int ufshcd_add_lus(struct ufs_hba *hba)
 			&hba->pwr_info,
 			sizeof(struct ufs_pa_layer_attr));
 		hba->clk_scaling.is_allowed = true;
-
-		ret = ufshcd_devfreq_init(hba);
-		if (ret)
-			goto out;
-
-		hba->clk_scaling.is_enabled = true;
-		ufshcd_init_clk_scaling_sysfs(hba);
 	}
 
 	/*
@@ -9010,6 +9006,12 @@ static void ufshcd_async_scan(void *data, async_cookie_t cookie)
 	/* Probe and add UFS logical units  */
 	ret = ufshcd_add_lus(hba);
 
+	/* Initialize devfreq and start devfreq monitor */
+	if (!ufshcd_devfreq_init(hba)) {
+		hba->clk_scaling.is_enabled = true;
+		ufshcd_init_clk_scaling_sysfs(hba);
+	}
+
 out:
 	pm_runtime_put_sync(hba->dev);
 
-- 
2.34.1