Re: [PATCH V3 4/9] phy: qcom-qmp-ufs: Refactor UFS PHY reset

Dmitry Baryshkov
2025-04-11T11:08:14Z

On Fri, 11 Apr 2025 at 13:50, Nitin Rawat <quic_nitirawa@quicinc.com> wrote:
>
>
>
> On 4/11/2025 1:38 AM, Dmitry Baryshkov wrote:
> > On Thu, Apr 10, 2025 at 02:30:57PM +0530, Nitin Rawat wrote:
> >> Refactor the UFS PHY reset handling to parse the reset logic only once
> >> during probe, instead of every resume.
> >>
> >> Move the UFS PHY reset parsing logic from qmp_phy_power_on to
> >> qmp_ufs_probe to avoid unnecessary parsing during resume.
> >
> > How did you solve the circular dependency issue being noted below?
>
> Hi Dmitry,
> As part of my patch, I moved the parsing logic from qmp_phy_power_on to
> qmp_ufs_probe to avoid unnecessary parsing during resume. I'm uncertain
> about the circular dependency issue and whether if it still exists.

It surely does. The reset controller is registered in the beginning of
ufs_qcom_init() and the PHY is acquired only a few lines below. It
creates a very small window for PHY driver to probe.
Which means, NAK, this patch doesn't look acceptable.

>
> Regards,
> Nitin
>
>
> >
> >>
> >> Co-developed-by: Ram Kumar Dwivedi <quic_rdwivedi@quicinc.com>
> >> Signed-off-by: Ram Kumar Dwivedi <quic_rdwivedi@quicinc.com>
> >> Signed-off-by: Nitin Rawat <quic_nitirawa@quicinc.com>
> >> ---
> >> drivers/phy/qualcomm/phy-qcom-qmp-ufs.c | 61 +++++++++++++------------
> >> 1 file changed, 33 insertions(+), 28 deletions(-)
> >>
> >> diff --git a/drivers/phy/qualcomm/phy-qcom-qmp-ufs.c b/drivers/phy/qualcomm/phy-qcom-qmp-ufs.c
> >> index 636dc3dc3ea8..12dad28cc1bd 100644
> >> --- a/drivers/phy/qualcomm/phy-qcom-qmp-ufs.c
> >> +++ b/drivers/phy/qualcomm/phy-qcom-qmp-ufs.c
> >> @@ -1799,38 +1799,11 @@ static int qmp_ufs_com_exit(struct qmp_ufs *qmp)
> >> static int qmp_ufs_power_on(struct phy *phy)
> >> {
> >> struct qmp_ufs *qmp = phy_get_drvdata(phy);
> >> - const struct qmp_phy_cfg *cfg = qmp->cfg;
> >> int ret;
> >> dev_vdbg(qmp->dev, "Initializing QMP phy\n");
> >>
> >> - if (cfg->no_pcs_sw_reset) {
> >> - /*
> >> - * Get UFS reset, which is delayed until now to avoid a
> >> - * circular dependency where UFS needs its PHY, but the PHY
> >> - * needs this UFS reset.
> >> - */
> >> - if (!qmp->ufs_reset) {
> >> - qmp->ufs_reset =
> >> - devm_reset_control_get_exclusive(qmp->dev,
> >> - "ufsphy");
> >> -
> >> - if (IS_ERR(qmp->ufs_reset)) {
> >> - ret = PTR_ERR(qmp->ufs_reset);
> >> - dev_err(qmp->dev,
> >> - "failed to get UFS reset: %d\n",
> >> - ret);
> >> -
> >> - qmp->ufs_reset = NULL;
> >> - return ret;
> >> - }
> >> - }
> >> - }
> >> -
> >> ret = qmp_ufs_com_init(qmp);
> >> - if (ret)
> >> - return ret;
> >> -
> >> - return 0;
> >> + return ret;
> >> }
> >>
> >> static int qmp_ufs_phy_calibrate(struct phy *phy)
> >> @@ -2088,6 +2061,34 @@ static int qmp_ufs_parse_dt(struct qmp_ufs *qmp)
> >> return 0;
> >> }
> >>
> >> +static int qmp_ufs_get_phy_reset(struct qmp_ufs *qmp)
> >> +{
> >> + const struct qmp_phy_cfg *cfg = qmp->cfg;
> >> + int ret;
> >> +
> >> + if (!cfg->no_pcs_sw_reset)
> >> + return 0;
> >> +
> >> + /*
> >> + * Get UFS reset, which is delayed until now to avoid a
> >> + * circular dependency where UFS needs its PHY, but the PHY
> >> + * needs this UFS reset.
> >> + */
> >> + if (!qmp->ufs_reset) {
> >> + qmp->ufs_reset =
> >> + devm_reset_control_get_exclusive(qmp->dev, "ufsphy");
> >
> > Strange indentation.
> >
> >> +
> >> + if (IS_ERR(qmp->ufs_reset)) {
> >> + ret = PTR_ERR(qmp->ufs_reset);
> >> + dev_err(qmp->dev, "failed to get PHY reset: %d\n", ret);
> >> + qmp->ufs_reset = NULL;
> >> + return ret;
> >> + }
> >> + }
> >> +
> >> + return 0;
> >> +}
> >> +
> >> static int qmp_ufs_probe(struct platform_device *pdev)
> >> {
> >> struct device *dev = &pdev->dev;
> >> @@ -2114,6 +2115,10 @@ static int qmp_ufs_probe(struct platform_device *pdev)
> >> if (ret)
> >> return ret;
> >>
> >> + ret = qmp_ufs_get_phy_reset(qmp);
> >> + if (ret)
> >> + return ret;
> >> +
> >> /* Check for legacy binding with child node. */
> >> np = of_get_next_available_child(dev->of_node, NULL);
> >> if (np) {
> >> --
> >> 2.48.1
> >>
> >
>

--
With best wishes
Dmitry