On 4/22/22 06:21, Manivannan Sadhasivam wrote:
In ufs_qcom_dev_ref_clk_ctrl(), it was noted that the ref_clk needs to be
stable for atleast 1us. Eventhough there is wmb() to make sure the write
^ ^
Some spaces are missing.
gets "completed", there is no guarantee that the write actually reached
the UFS device. There is a good chance that the write could be stored in
a Write Buffer (WB). In that case, eventhough the CPU waits for 1us, the
^
missing space----------------------------
ref_clk might not be stable for that period.
So lets do a readl() to make sure that the previous write has reached the
UFS device before udelay().
Cc: stable@xxxxxxxxxxxxxxx
Fixes: f06fcc7155dc ("scsi: ufs-qcom: add QUniPro hardware support and power optimizations")
Signed-off-by: Manivannan Sadhasivam <manivannan.sadhasivam@xxxxxxxxxx>
---
drivers/scsi/ufs/ufs-qcom.c | 6 ++++++
1 file changed, 6 insertions(+)
diff --git a/drivers/scsi/ufs/ufs-qcom.c b/drivers/scsi/ufs/ufs-qcom.c
index 5f0a8f646eb5..5b9986c63eed 100644
--- a/drivers/scsi/ufs/ufs-qcom.c
+++ b/drivers/scsi/ufs/ufs-qcom.c
@@ -690,6 +690,12 @@ static void ufs_qcom_dev_ref_clk_ctrl(struct ufs_qcom_host *host, bool enable)
/* ensure that ref_clk is enabled/disabled before we return */
wmb();
+ /*
+ * Make sure the write to ref_clk reaches the destination and
+ * not stored in a Write Buffer (WB).
+ */
+ readl(host->dev_ref_clk_ctrl_mmio);
+
/*
* If we call hibern8 exit after this, we need to make sure that
* device ref_clk is stable for at least 1us before the hibern8
The comment above the wmb() call looks wrong to me. How about removing
that wmb() call?
Thanks,
Bart.
