linux-kernel - Re: [PATCH v2 7/9] phy: qcom-qmp: Utilize UFS reset controller

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Date:   Tue, 5 Feb 2019 10:00:05 -0800
From:   Evan Green <evgreen@...omium.org>
To:     Stephen Boyd <swboyd@...omium.org>
Cc:     Andy Gross <andy.gross@...aro.org>,
        Kishon Vijay Abraham I <kishon@...com>,
        Rob Herring <robh+dt@...nel.org>,
        Can Guo <cang@...eaurora.org>,
        Douglas Anderson <dianders@...omium.org>,
        Asutosh Das <asutoshd@...eaurora.org>,
        Vivek Gautam <vivek.gautam@...eaurora.org>,
        Jeffrey Hugo <jhugo@...eaurora.org>,
        LKML <linux-kernel@...r.kernel.org>,
        Manu Gautam <mgautam@...eaurora.org>
Subject: Re: [PATCH v2 7/9] phy: qcom-qmp: Utilize UFS reset controller

On Fri, Feb 1, 2019 at 10:00 AM Stephen Boyd <swboyd@...omium.org> wrote:
>
> Quoting Evan Green (2019-01-23 14:11:35)
> > @@ -1144,6 +1150,8 @@ static const struct qmp_phy_cfg sdm845_ufsphy_cfg = {
> >
> >         .is_dual_lane_phy       = true,
> >         .no_pcs_sw_reset        = true,
> > +
> > +       .has_ufsphy_reset       = true,
>
> Is this the same as .no_pcs_sw_reset implying that .has_ufsphy_reset? Or
> it's possible to have no resets at all? I'd think there's a reset in the
> phy or in the pcs and so we could just have one bit telling us which
> type of reset to perform.

Ok. I guess pcs_sw_reset is the same reset as this bit that seems to
bubble up in the ufs-qcom controller? If some new crazy qcom chip
comes up that has both resets or no resets, this should be pretty
simple to disentangle.

>
> >  };
> >
> >  static const struct qmp_phy_cfg msm8998_usb3phy_cfg = {
> > @@ -1314,6 +1322,9 @@ static int qcom_qmp_phy_com_exit(struct qcom_qmp *qmp)
> >                 return 0;
> >         }
> >
> > +       if (qmp->ufs_reset)
> > +               reset_control_assert(qmp->ufs_reset);
> > +
> >         if (cfg->has_phy_com_ctrl) {
> >                 qphy_setbits(serdes, cfg->regs[QPHY_COM_START_CONTROL],
> >                              SERDES_START | PCS_START);
> > @@ -1351,6 +1362,33 @@ static int qcom_qmp_phy_init(struct phy *phy)
> >
> >         dev_vdbg(qmp->dev, "Initializing QMP phy\n");
> >
> > +       if (cfg->has_ufsphy_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)) {
> > +                               dev_err(qmp->dev,
> > +                                       "failed to get UFS reset: %d\n",
> > +                                       PTR_ERR(qmp->ufs_reset));
> > +
> > +                               ret = PTR_ERR(qmp->ufs_reset);
>
> Do this ret conversion once and then print it after?

Yeah, good idea.

>
> > +                               qmp->ufs_reset = NULL;
> > +                               return ret;
> > +                       }
> > +               }
> > +
> > +               ret = reset_control_assert(qmp->ufs_reset);
> > +               if (ret)
> > +                       goto err_lane_rst;
> > +       }
> > +
> >         ret = qcom_qmp_phy_com_init(qphy);
> >         if (ret)
> >                 return ret;