linux-kernel - [PATCH 1/1] scsi: ufshcd: fix possible unclocked register access

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Message-Id: <1517282545-10502-1-git-send-email-asutoshd@codeaurora.org>
Date:   Tue, 30 Jan 2018 08:52:25 +0530
From:   Asutosh Das <asutoshd@...eaurora.org>
To:     subhashj@...eaurora.org, cang@...eaurora.org,
        vivek.gautam@...eaurora.org, rnayak@...eaurora.org,
        vinholikatti@...il.com, jejb@...ux.vnet.ibm.com,
        martin.petersen@...cle.com
Cc:     linux-scsi@...r.kernel.org,
        Venkat Gopalakrishnan <venkatg@...eaurora.org>,
        Asutosh Das <asutoshd@...eaurora.org>,
        linux-kernel@...r.kernel.org (open list)
Subject: [PATCH 1/1] scsi: ufshcd: fix possible unclocked register access

From: Subhash Jadavani <subhashj@...eaurora.org>

vendor specific setup_clocks ops may depend on clocks managed by ufshcd
driver so if the vendor specific setup_clocks callback is called when
the required clocks are turned off, it results into unclocked register
access.

This change make sure that required clocks are enabled before vendor
specific setup_clocks callback is called.

Signed-off-by: Subhash Jadavani <subhashj@...eaurora.org>
Signed-off-by: Venkat Gopalakrishnan <venkatg@...eaurora.org>
Signed-off-by: Can Guo <cang@...eaurora.org>
Signed-off-by: Asutosh Das <asutoshd@...eaurora.org>
---
 drivers/scsi/ufs/ufshcd.c | 26 ++++++++++++++++++++------
 1 file changed, 20 insertions(+), 6 deletions(-)

diff --git a/drivers/scsi/ufs/ufshcd.c b/drivers/scsi/ufs/ufshcd.c
index 8af2af3..c5ee686 100644
--- a/drivers/scsi/ufs/ufshcd.c
+++ b/drivers/scsi/ufs/ufshcd.c
@@ -6763,9 +6763,16 @@ static int __ufshcd_setup_clocks(struct ufs_hba *hba, bool on,
 	if (list_empty(head))
 		goto out;
 
-	ret = ufshcd_vops_setup_clocks(hba, on, PRE_CHANGE);
-	if (ret)
-		return ret;
+	/*
+	 * vendor specific setup_clocks ops may depend on clocks managed by
+	 * this standard driver hence call the vendor specific setup_clocks
+	 * before disabling the clocks managed here.
+	 */
+	if (!on) {
+		ret = ufshcd_vops_setup_clocks(hba, on, PRE_CHANGE);
+		if (ret)
+			return ret;
+	}
 
 	list_for_each_entry(clki, head, list) {
 		if (!IS_ERR_OR_NULL(clki->clk)) {
@@ -6789,9 +6796,16 @@ static int __ufshcd_setup_clocks(struct ufs_hba *hba, bool on,
 		}
 	}
 
-	ret = ufshcd_vops_setup_clocks(hba, on, POST_CHANGE);
-	if (ret)
-		return ret;
+	/*
+	 * vendor specific setup_clocks ops may depend on clocks managed by
+	 * this standard driver hence call the vendor specific setup_clocks
+	 * after enabling the clocks managed here.
+	 */
+	if (on) {
+		ret = ufshcd_vops_setup_clocks(hba, on, POST_CHANGE);
+		if (ret)
+			return ret;
+	}
 
 out:
 	if (ret) {
-- 
Qualcomm India Private Limited, on behalf of Qualcomm Innovation Center, Inc. 
Qualcomm Innovation Center, Inc. is a member of Code Aurora Forum, a Linux Foundation Collaborative Project.