On Tue, Mar 18, 2025 at 08:19:44PM +0530, Nitin Rawat wrote:
> Introduce ufs_qcom_phy_power_on and ufs_qcom_phy_power_off wrapper
> functions with mutex protection to ensure safe usage of is_phy_pwr_on
> and prevent possible race conditions.
>
Please describe the problem properly here. Are you introducing the mutex
because there is a problem, or because you want to be "safe"?
Why is it "refcounted", is the calling code paths no longer in sync? How
long has the current implementation been broken?
Regards,
Bjorn
> Co-developed-by: Can Guo <quic_cang@xxxxxxxxxxx>
> Signed-off-by: Can Guo <quic_cang@xxxxxxxxxxx>
> Signed-off-by: Nitin Rawat <quic_nitirawa@xxxxxxxxxxx>
> ---
> drivers/ufs/host/ufs-qcom.c | 44 +++++++++++++++++++++++++++++++------
> drivers/ufs/host/ufs-qcom.h | 4 ++++
> 2 files changed, 41 insertions(+), 7 deletions(-)
>
> diff --git a/drivers/ufs/host/ufs-qcom.c b/drivers/ufs/host/ufs-qcom.c
> index 5c7b6c75d669..8f80724e64b9 100644
> --- a/drivers/ufs/host/ufs-qcom.c
> +++ b/drivers/ufs/host/ufs-qcom.c
> @@ -421,6 +421,38 @@ static u32 ufs_qcom_get_hs_gear(struct ufs_hba *hba)
> return UFS_HS_G3;
> }
>
> +static int ufs_qcom_phy_power_on(struct ufs_hba *hba)
> +{
> + struct ufs_qcom_host *host = ufshcd_get_variant(hba);
> + struct phy *phy = host->generic_phy;
> + int ret = 0;
> +
> + guard(mutex)(&host->phy_mutex);
> + if (!host->is_phy_pwr_on) {
> + ret = phy_power_on(phy);
> + if (!ret)
> + host->is_phy_pwr_on = true;
> + }
> +
> + return ret;
> +}
> +
> +static int ufs_qcom_phy_power_off(struct ufs_hba *hba)
> +{
> + struct ufs_qcom_host *host = ufshcd_get_variant(hba);
> + struct phy *phy = host->generic_phy;
> + int ret = 0;
> +
> + guard(mutex)(&host->phy_mutex);
> + if (host->is_phy_pwr_on) {
> + ret = phy_power_off(phy);
> + if (!ret)
> + host->is_phy_pwr_on = false;
> + }
> +
> + return ret;
> +}
> +
> static int ufs_qcom_power_up_sequence(struct ufs_hba *hba)
> {
> struct ufs_qcom_host *host = ufshcd_get_variant(hba);
> @@ -449,7 +481,7 @@ static int ufs_qcom_power_up_sequence(struct ufs_hba *hba)
> return ret;
>
> if (phy->power_count) {
> - phy_power_off(phy);
> + ufs_qcom_phy_power_off(hba);
> phy_exit(phy);
> }
>
> @@ -466,7 +498,7 @@ static int ufs_qcom_power_up_sequence(struct ufs_hba *hba)
> goto out_disable_phy;
>
> /* power on phy - start serdes and phy's power and clocks */
> - ret = phy_power_on(phy);
> + ret = ufs_qcom_phy_power_on(hba);
> if (ret) {
> dev_err(hba->dev, "%s: phy power on failed, ret = %d\n",
> __func__, ret);
> @@ -1017,7 +1049,6 @@ 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);
> - struct phy *phy = host->generic_phy;
> int err;
>
> /*
> @@ -1037,7 +1068,7 @@ static int ufs_qcom_setup_clocks(struct ufs_hba *hba, bool on,
> /* disable device ref_clk */
> ufs_qcom_dev_ref_clk_ctrl(host, false);
> }
> - err = phy_power_off(phy);
> + err = ufs_qcom_phy_power_off(hba);
> if (err) {
> dev_err(hba->dev, "phy power off failed, ret=%d\n", err);
> return err;
> @@ -1046,7 +1077,7 @@ static int ufs_qcom_setup_clocks(struct ufs_hba *hba, bool on,
> break;
> case POST_CHANGE:
> if (on) {
> - err = phy_power_on(phy);
> + err = ufs_qcom_phy_power_on(hba);
> if (err) {
> dev_err(hba->dev, "phy power on failed, ret = %d\n", err);
> return err;
> @@ -1233,10 +1264,9 @@ static int ufs_qcom_init(struct ufs_hba *hba)
> static void ufs_qcom_exit(struct ufs_hba *hba)
> {
> struct ufs_qcom_host *host = ufshcd_get_variant(hba);
> - struct phy *phy = host->generic_phy;
>
> ufs_qcom_disable_lane_clks(host);
> - phy_power_off(phy);
> + ufs_qcom_phy_power_off(hba);
> phy_exit(host->generic_phy);
> }
>
> diff --git a/drivers/ufs/host/ufs-qcom.h b/drivers/ufs/host/ufs-qcom.h
> index d0e6ec9128e7..3db29fbcd40b 100644
> --- a/drivers/ufs/host/ufs-qcom.h
> +++ b/drivers/ufs/host/ufs-qcom.h
> @@ -252,6 +252,10 @@ struct ufs_qcom_host {
> u32 phy_gear;
>
> bool esi_enabled;
> + /* flag to check if phy is powered on */
> + bool is_phy_pwr_on;
> + /* Protect the usage of is_phy_pwr_on against racing */
> + struct mutex phy_mutex;
> };
>
> struct ufs_qcom_drvdata {
> --
> 2.48.1
>
>
