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| author | Andrew Halaney <ahalaney@redhat.com> | 2024-03-29 23:46:44 +0300 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2024-06-12 12:03:09 +0300 |
| commit | b52ce65b4603de52549d102e21fe97e19b318729 (patch) | |
| tree | fe79fd317170624c596663e8eb6d097ac52b5c1e /drivers/ufs | |
| parent | bfda254ceb5bb5984335a662e32ff4ad9492e485 (diff) | |
| download | linux-b52ce65b4603de52549d102e21fe97e19b318729.tar.xz | |
scsi: ufs: qcom: Perform read back after writing REG_UFS_SYS1CLK_1US
[ Upstream commit a862fafa263aea0f427d51aca6ff7fd9eeaaa8bd ]
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>
Signed-off-by: Sasha Levin <sashal@kernel.org>
Diffstat (limited to 'drivers/ufs')
| -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 8ad1415e10b6..a5d981d3dd6b 100644 --- a/drivers/ufs/host/ufs-qcom.c +++ b/drivers/ufs/host/ufs-qcom.c @@ -432,7 +432,7 @@ 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); } if (ufs_qcom_cap_qunipro(host)) |