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| author | Andrew Halaney <ahalaney@redhat.com> | 2024-03-29 23:46:44 +0300 |
|---|---|---|
| committer | Martin K. Petersen <martin.petersen@oracle.com> | 2024-04-06 04:06:28 +0300 |
| commit | a862fafa263aea0f427d51aca6ff7fd9eeaaa8bd (patch) | |
| tree | 8bcc3ee186e36d4a0a0140955628bb6cf79a5738 | |
| parent | c4d28e06b0c94636f6e35d003fa9ebac0a94e1ae (diff) | |
| download | linux-a862fafa263aea0f427d51aca6ff7fd9eeaaa8bd.tar.xz | |
scsi: ufs: qcom: Perform read back after writing REG_UFS_SYS1CLK_1US
Currently after writing to REG_UFS_SYS1CLK_1US a mb() is used to ensure
that write has gone through to the device.
mb() ensures that the write completes, but completion doesn't mean that it
isn't stored in a buffer somewhere. The recommendation for ensuring this
bit has taken effect on the device is to perform a read back to force it to
make it all the way to the device. This is documented in device-io.rst and
a talk by Will Deacon on this can be seen over here:
https://youtu.be/i6DayghhA8Q?si=MiyxB5cKJXSaoc01&t=1678
Let's do that to ensure the bit hits the device. Because the mb()'s purpose
wasn't to add extra ordering (on top of the ordering guaranteed by
writel()/readl()), it can safely be removed.
Fixes: f06fcc7155dc ("scsi: ufs-qcom: add QUniPro hardware support and power optimizations")
Reviewed-by: Can Guo <quic_cang@quicinc.com>
Signed-off-by: Andrew Halaney <ahalaney@redhat.com>
Link: https://lore.kernel.org/r/20240329-ufs-reset-ensure-effect-before-delay-v5-2-181252004586@redhat.com
Reviewed-by: Manivannan Sadhasivam <manivannan.sadhasivam@linaro.org>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>
| -rw-r--r-- | drivers/ufs/host/ufs-qcom.c | 2 |
1 files changed, 1 insertions, 1 deletions
diff --git a/drivers/ufs/host/ufs-qcom.c b/drivers/ufs/host/ufs-qcom.c index 8d68bd21ae73..46f8a74e5037 100644 --- a/drivers/ufs/host/ufs-qcom.c +++ b/drivers/ufs/host/ufs-qcom.c @@ -501,7 +501,7 @@ static int ufs_qcom_cfg_timers(struct ufs_hba *hba, u32 gear, * make sure above write gets applied before we return from * this function. */ - mb(); + ufshcd_readl(hba, REG_UFS_SYS1CLK_1US); } return 0; |