diff options
author | Martin K. Petersen <martin.petersen@oracle.com> | 2024-04-06 04:07:23 +0300 |
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committer | Martin K. Petersen <martin.petersen@oracle.com> | 2024-04-06 04:07:23 +0300 |
commit | 0e0a4da35284c85225e3b128912582ebc73256c8 (patch) | |
tree | f65d0272efaa5bbb2c3121a967629953eefca635 /drivers/ufs/host | |
parent | 9282899e1e7e245c464f5996119fb06d48b97d4a (diff) | |
parent | 356a8ce7cd5037fa0863c2ac83a35c8ebf6e0e02 (diff) | |
download | linux-0e0a4da35284c85225e3b128912582ebc73256c8.tar.xz |
Merge patch series "scsi: ufs: Remove overzealous memory barriers"
Andrew Halaney <ahalaney@redhat.com> says:
Please review with care as I'm not all that confident in this subject.
UFS has a lot of mb() variants used, most with comments saying "ensure
this takes effect before continuing". mb()'s aren't really the way to
guarantee that, a read back is the best method.
Some of these though I think could go a step further and remove the
mb() variant without a read back. As far as I can tell there's no real
reason to ensure it takes effect in most cases (there's no delay() or
anything afterwards, and eventually another readl()/writel() happens
which is by definition ordered). Some of the patches in this series do
that if I was confident it was safe (or a reviewer pointed out prior
that they thought it was safe to do so).
Thanks in advance for the help,
Andrew
Link: https://lore.kernel.org/r/20240329-ufs-reset-ensure-effect-before-delay-v5-0-181252004586@redhat.com
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>
Diffstat (limited to 'drivers/ufs/host')
-rw-r--r-- | drivers/ufs/host/cdns-pltfrm.c | 2 | ||||
-rw-r--r-- | drivers/ufs/host/ufs-qcom.c | 12 | ||||
-rw-r--r-- | drivers/ufs/host/ufs-qcom.h | 12 |
3 files changed, 9 insertions, 17 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; } diff --git a/drivers/ufs/host/ufs-qcom.c b/drivers/ufs/host/ufs-qcom.c index 06859e17b67b..1439c1df0481 100644 --- a/drivers/ufs/host/ufs-qcom.c +++ b/drivers/ufs/host/ufs-qcom.c @@ -278,9 +278,6 @@ static void ufs_qcom_select_unipro_mode(struct ufs_qcom_host *host) if (host->hw_ver.major >= 0x05) ufshcd_rmwl(host->hba, QUNIPRO_G4_SEL, 0, REG_UFS_CFG0); - - /* make sure above configuration is applied before we return */ - mb(); } /* @@ -409,7 +406,7 @@ static void ufs_qcom_enable_hw_clk_gating(struct ufs_hba *hba) REG_UFS_CFG2); /* Ensure that HW clock gating is enabled before next operations */ - mb(); + ufshcd_readl(hba, REG_UFS_CFG2); } static int ufs_qcom_hce_enable_notify(struct ufs_hba *hba, @@ -501,7 +498,7 @@ 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; @@ -1445,11 +1442,6 @@ int ufs_qcom_testbus_config(struct ufs_qcom_host *host) (u32)host->testbus.select_minor << offset, reg); ufs_qcom_enable_test_bus(host); - /* - * Make sure the test bus configuration is - * committed before returning. - */ - mb(); return 0; } diff --git a/drivers/ufs/host/ufs-qcom.h b/drivers/ufs/host/ufs-qcom.h index 9dd9a391ebb7..b9de170983c9 100644 --- a/drivers/ufs/host/ufs-qcom.h +++ b/drivers/ufs/host/ufs-qcom.h @@ -151,10 +151,10 @@ static inline void ufs_qcom_assert_reset(struct ufs_hba *hba) ufshcd_rmwl(hba, UFS_PHY_SOFT_RESET, UFS_PHY_SOFT_RESET, REG_UFS_CFG1); /* - * Make sure assertion of ufs phy reset is written to - * register before returning + * Dummy read to ensure the write takes effect before doing any sort + * of delay */ - mb(); + ufshcd_readl(hba, REG_UFS_CFG1); } static inline void ufs_qcom_deassert_reset(struct ufs_hba *hba) @@ -162,10 +162,10 @@ static inline void ufs_qcom_deassert_reset(struct ufs_hba *hba) ufshcd_rmwl(hba, UFS_PHY_SOFT_RESET, 0, REG_UFS_CFG1); /* - * Make sure de-assertion of ufs phy reset is written to - * register before returning + * Dummy read to ensure the write takes effect before doing any sort + * of delay */ - mb(); + ufshcd_readl(hba, REG_UFS_CFG1); } /* Host controller hardware version: major.minor.step */ |