Re: [PATCH v2 05/10] scsi: ufshcd: fix possible unclocked register access

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On 2018-05-03 04:07, Asutosh Das wrote:
From: Subhash Jadavani <subhashj@xxxxxxxxxxxxxx>

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@xxxxxxxxxxxxxx>
Signed-off-by: Venkat Gopalakrishnan <venkatg@xxxxxxxxxxxxxx>
Signed-off-by: Can Guo <cang@xxxxxxxxxxxxxx>
Signed-off-by: Asutosh Das <asutoshd@xxxxxxxxxxxxxx>
---
 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 838ba8f0..dfeb194 100644
--- a/drivers/scsi/ufs/ufshcd.c
+++ b/drivers/scsi/ufs/ufshcd.c
@@ -6780,9 +6780,16 @@ 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)) {
@@ -6806,9 +6813,16 @@ 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) {

Looks good to me.

--
The Qualcomm Innovation Center, Inc. is a member of Code Aurora Forum,
a Linux Foundation Collaborative Project



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