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Date: Sat, 08 Oct 2016 12:33:02 +0900
From: Kiwoong Kim <kwmad.kim@...sung.com>
To: 'Subhash Jadavani' <subhashj@...eaurora.org>,
vinholikatti@...il.com, jejb@...ux.vnet.ibm.com,
martin.petersen@...cle.com
Cc: "'open list:UNIVERSAL FLASH STORAGE HOST CONTROLLER DRIVER'"
<linux-scsi@...r.kernel.org>,
'open list' <linux-kernel@...r.kernel.org>
Subject: RE: [RESEND PATCH v3] scsi: ufshcd: fix possible unclocked register
access
Reviewed-by: Kiwoong Kim <kwmad.kim@...sung.com>
> Vendor specific setup_clocks callback may require the clocks managed
> by ufshcd driver to be ON. So if the vendor specific setup_clocks callback
> is called while the required clocks are turned off, it could result into
> unclocked register access.
>
> To prevent possible unclock register access, this change adds one more
> argument to setup_clocks callback to let it know whether it is called
> pre/post the clock changes by core driver.
>
> Signed-off-by: Subhash Jadavani <subhashj@...eaurora.org>
> ---
> Changes from v2:
> * Added one more argument to setup_clocks callback, this should address
> Kiwoong Kim's comments on v2.
>
> Changes from v1:
> * Don't call ufshcd_vops_setup_clocks() again for clock off
> ---
> drivers/scsi/ufs/ufs-qcom.c | 10 ++++++----
> drivers/scsi/ufs/ufshcd.c | 17 ++++++++---------
> drivers/scsi/ufs/ufshcd.h | 8 +++++---
> 3 files changed, 19 insertions(+), 16 deletions(-)
>
> diff --git a/drivers/scsi/ufs/ufs-qcom.c b/drivers/scsi/ufs/ufs-qcom.c
> index 3aedf73..3c4f602 100644
> --- a/drivers/scsi/ufs/ufs-qcom.c
> +++ b/drivers/scsi/ufs/ufs-qcom.c
> @@ -1094,10 +1094,12 @@ static void ufs_qcom_set_caps(struct ufs_hba *hba)
> * ufs_qcom_setup_clocks - enables/disable clocks
> * @hba: host controller instance
> * @on: If true, enable clocks else disable them.
> + * @status: PRE_CHANGE or POST_CHANGE notify
> *
> * Returns 0 on success, non-zero on failure.
> */
> -static int ufs_qcom_setup_clocks(struct ufs_hba *hba, bool on)
> +static int ufs_qcom_setup_clocks(struct ufs_hba *hba, bool on,
> + enum ufs_notify_change_status status)
> {
> struct ufs_qcom_host *host = ufshcd_get_variant(hba);
> int err;
> @@ -1111,7 +1113,7 @@ static int ufs_qcom_setup_clocks(struct ufs_hba
*hba,
> bool on)
> if (!host)
> return 0;
>
> - if (on) {
> + if (on && (status == POST_CHANGE)) {
> err = ufs_qcom_phy_enable_iface_clk(host->generic_phy);
> if (err)
> goto out;
> @@ -1130,7 +1132,7 @@ static int ufs_qcom_setup_clocks(struct ufs_hba
*hba,
> bool on)
> if (vote == host->bus_vote.min_bw_vote)
> ufs_qcom_update_bus_bw_vote(host);
>
> - } else {
> + } else if (!on && (status == PRE_CHANGE)) {
>
> /* M-PHY RMMI interface clocks can be turned off */
> ufs_qcom_phy_disable_iface_clk(host->generic_phy);
> @@ -1254,7 +1256,7 @@ static int ufs_qcom_init(struct ufs_hba *hba)
> ufs_qcom_set_caps(hba);
> ufs_qcom_advertise_quirks(hba);
>
> - ufs_qcom_setup_clocks(hba, true);
> + ufs_qcom_setup_clocks(hba, true, POST_CHANGE);
>
> if (hba->dev->id < MAX_UFS_QCOM_HOSTS)
> ufs_qcom_hosts[hba->dev->id] = host;
> diff --git a/drivers/scsi/ufs/ufshcd.c b/drivers/scsi/ufs/ufshcd.c
> index 05c7456..571a2f6 100644
> --- a/drivers/scsi/ufs/ufshcd.c
> +++ b/drivers/scsi/ufs/ufshcd.c
> @@ -5389,6 +5389,10 @@ static int __ufshcd_setup_clocks(struct ufs_hba
> *hba, bool on,
> if (!head || list_empty(head))
> goto out;
>
> + ret = ufshcd_vops_setup_clocks(hba, on, PRE_CHANGE);
> + if (ret)
> + return ret;
> +
> list_for_each_entry(clki, head, list) {
> if (!IS_ERR_OR_NULL(clki->clk)) {
> if (skip_ref_clk && !strcmp(clki->name, "ref_clk"))
> @@ -5410,7 +5414,10 @@ static int __ufshcd_setup_clocks(struct ufs_hba
> *hba, bool on,
> }
> }
>
> - ret = ufshcd_vops_setup_clocks(hba, on);
> + ret = ufshcd_vops_setup_clocks(hba, on, POST_CHANGE);
> + if (ret)
> + return ret;
> +
> out:
> if (ret) {
> list_for_each_entry(clki, head, list) {
> @@ -5500,8 +5507,6 @@ static void ufshcd_variant_hba_exit(struct ufs_hba
> *hba)
> if (!hba->vops)
> return;
>
> - ufshcd_vops_setup_clocks(hba, false);
> -
> ufshcd_vops_setup_regulators(hba, false);
>
> ufshcd_vops_exit(hba);
> @@ -5905,10 +5910,6 @@ disable_clks:
> if (ret)
> goto set_link_active;
>
> - ret = ufshcd_vops_setup_clocks(hba, false);
> - if (ret)
> - goto vops_resume;
> -
> if (!ufshcd_is_link_active(hba))
> ufshcd_setup_clocks(hba, false);
> else
> @@ -5925,8 +5926,6 @@ disable_clks:
> ufshcd_hba_vreg_set_lpm(hba);
> goto out;
>
> -vops_resume:
> - ufshcd_vops_resume(hba, pm_op);
> set_link_active:
> ufshcd_vreg_set_hpm(hba);
> if (ufshcd_is_link_hibern8(hba) && !ufshcd_uic_hibern8_exit(hba))
> diff --git a/drivers/scsi/ufs/ufshcd.h b/drivers/scsi/ufs/ufshcd.h
> index 430bef1..afff7f4 100644
> --- a/drivers/scsi/ufs/ufshcd.h
> +++ b/drivers/scsi/ufs/ufshcd.h
> @@ -273,7 +273,8 @@ struct ufs_hba_variant_ops {
> u32 (*get_ufs_hci_version)(struct ufs_hba *);
> int (*clk_scale_notify)(struct ufs_hba *, bool,
> enum ufs_notify_change_status);
> - int (*setup_clocks)(struct ufs_hba *, bool);
> + int (*setup_clocks)(struct ufs_hba *, bool,
> + enum ufs_notify_change_status);
> int (*setup_regulators)(struct ufs_hba *, bool);
> int (*hce_enable_notify)(struct ufs_hba *,
> enum ufs_notify_change_status);
> @@ -755,10 +756,11 @@ static inline int
> ufshcd_vops_clk_scale_notify(struct ufs_hba *hba,
> return 0;
> }
>
> -static inline int ufshcd_vops_setup_clocks(struct ufs_hba *hba, bool on)
> +static inline int ufshcd_vops_setup_clocks(struct ufs_hba *hba, bool on,
> + enum ufs_notify_change_status
status)
> {
> if (hba->vops && hba->vops->setup_clocks)
> - return hba->vops->setup_clocks(hba, on);
> + return hba->vops->setup_clocks(hba, on, status);
> return 0;
> }
>
> --
> The Qualcomm Innovation Center, Inc. is a member of the Code Aurora Forum,
> a Linux Foundation Collaborative Project
>
> --
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