[PATCH 4/9] scsi: ufshcd: fix possible unclocked register access

From: Asutosh Das
Date: Wed Feb 21 2018 - 00:03:47 EST


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 8d3f8ce..7a4df95 100644
--- a/drivers/scsi/ufs/ufshcd.c
+++ b/drivers/scsi/ufs/ufshcd.c
@@ -6782,9 +6782,16 @@ 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)) {
@@ -6808,9 +6815,16 @@ 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) {
--
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