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| author | Andrew Halaney <ahalaney@redhat.com> | 2024-03-29 23:46:48 +0300 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2024-05-30 10:44:17 +0300 |
| commit | 4bfc22dbf7bd2d707be1bb1511b4722c11423508 (patch) | |
| tree | 189ce7aab621fc26edc02f89c74bddc448ce53a7 /drivers/ufs | |
| parent | bb5f55793df6e9ea007c5e8fcbe91d49ced371ed (diff) | |
| download | linux-4bfc22dbf7bd2d707be1bb1511b4722c11423508.tar.xz | |
scsi: ufs: cdns-pltfrm: Perform read back after writing HCLKDIV
[ Upstream commit b715c55daf598aac8fa339048e4ca8a0916b332e ]
Currently, HCLKDIV is written to and then completed with an mb().
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: d90996dae8e4 ("scsi: ufs: Add UFS platform driver for Cadence UFS")
Reviewed-by: Manivannan Sadhasivam <manivannan.sadhasivam@linaro.org>
Signed-off-by: Andrew Halaney <ahalaney@redhat.com>
Link: https://lore.kernel.org/r/20240329-ufs-reset-ensure-effect-before-delay-v5-6-181252004586@redhat.com
Reviewed-by: Bart Van Assche <bvanassche@acm.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/cdns-pltfrm.c | 2 |
1 files changed, 1 insertions, 1 deletions
diff --git a/drivers/ufs/host/cdns-pltfrm.c b/drivers/ufs/host/cdns-pltfrm.c index bb30267da471..66811d8d1929 100644 --- a/drivers/ufs/host/cdns-pltfrm.c +++ b/drivers/ufs/host/cdns-pltfrm.c @@ -136,7 +136,7 @@ static int cdns_ufs_set_hclkdiv(struct ufs_hba *hba) * Make sure the register was updated, * UniPro layer will not work with an incorrect value. */ - mb(); + ufshcd_readl(hba, CDNS_UFS_REG_HCLKDIV); return 0; } |