linux-kernel - Re: [PATCH V2 2/6] phy: qcom-qmp-ufs: Refactor phy_power_on and phy

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Message-ID: <xn2oexjb6s7pdh4lpligc47jlyuxvwvuuh6obvr5z3ggqi2qsa@xjttnszx5eq3>
Date: Thu, 10 Apr 2025 23:00:00 +0300
From: Dmitry Baryshkov <dmitry.baryshkov@....qualcomm.com>
To: Nitin Rawat <quic_nitirawa@...cinc.com>
Cc: neil.armstrong@...aro.org, vkoul@...nel.org, kishon@...nel.org,
        manivannan.sadhasivam@...aro.org,
        James.Bottomley@...senpartnership.com, martin.petersen@...cle.com,
        konrad.dybcio@....qualcomm.com, quic_rdwivedi@...cinc.com,
        linux-arm-msm@...r.kernel.org, linux-phy@...ts.infradead.org,
        linux-kernel@...r.kernel.org, linux-scsi@...r.kernel.org,
        Can Guo <quic_cang@...cinc.com>
Subject: Re: [PATCH V2 2/6] phy: qcom-qmp-ufs: Refactor phy_power_on and
 phy_calibrate callbacks

On Thu, Apr 10, 2025 at 02:43:52PM +0530, Nitin Rawat wrote:
> 
> 
> On 3/18/2025 8:39 PM, neil.armstrong@...aro.org wrote:
> > On 18/03/2025 15:49, Nitin Rawat wrote:
> > > Commit 052553af6a31 ("ufs/phy: qcom: Refactor to use phy_init call")
> > > puts enabling regulators & clks, calibrating UFS PHY, starting serdes
> > > and polling PCS ready status into phy_power_on.
> > > 
> > > In Current code regulators enable, clks enable, calibrating UFS PHY,
> > > start_serdes and polling PCS_ready_status are part of phy_power_on.
> > > 
> > > UFS PHY registers are retained after power collapse, meaning calibrating
> > > UFS PHY, start_serdes and polling PCS_ready_status can be done only when
> > > hba is powered_on, and not needed every time when phy_power_on is called
> > > during resume. Hence keep the code which enables PHY's regulators & clks
> > > in phy_power_on and move the rest steps into phy_calibrate function.
> > > 
> > > Refactor the code to retain PHY regulators & clks in phy_power_on and
> > > move out rest of the code to new phy_calibrate function.
> > > 
> > > Co-developed-by: Can Guo <quic_cang@...cinc.com>
> > > Signed-off-by: Can Guo <quic_cang@...cinc.com>
> > > Signed-off-by: Nitin Rawat <quic_nitirawa@...cinc.com>
> > > ---
> > >   drivers/phy/qualcomm/phy-qcom-qmp-ufs.c | 18 ++----------------
> > >   1 file changed, 2 insertions(+), 16 deletions(-)
> > > 
> > > diff --git a/drivers/phy/qualcomm/phy-qcom-qmp-ufs.c b/drivers/phy/
> > > qualcomm/phy-qcom-qmp-ufs.c
> > > index bb836bc0f736..0089ee80f852 100644
> > > --- a/drivers/phy/qualcomm/phy-qcom-qmp-ufs.c
> > > +++ b/drivers/phy/qualcomm/phy-qcom-qmp-ufs.c
> > > @@ -1796,7 +1796,7 @@ static int qmp_ufs_com_exit(struct qmp_ufs *qmp)
> > >       return 0;
> > >   }
> > > 
> > > -static int qmp_ufs_init(struct phy *phy)
> > > +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;
> > > @@ -1898,21 +1898,6 @@ static int qmp_ufs_exit(struct phy *phy)
> > >       return 0;
> > >   }
> > > 
> > > -static int qmp_ufs_power_on(struct phy *phy)
> > > -{
> > > -    int ret;
> > > -
> > > -    ret = qmp_ufs_init(phy);
> > > -    if (ret)
> > > -        return ret;
> > > -
> > > -    ret = qmp_ufs_phy_calibrate(phy);
> > > -    if (ret)
> > > -        qmp_ufs_exit(phy);
> > > -
> > > -    return ret;
> > > -}
> > > -
> > >   static int qmp_ufs_disable(struct phy *phy)
> > >   {
> > >       int ret;
> > > @@ -1942,6 +1927,7 @@ static int qmp_ufs_set_mode(struct phy *phy,
> > > enum phy_mode mode, int submode)
> > >   static const struct phy_ops qcom_qmp_ufs_phy_ops = {
> > >       .power_on    = qmp_ufs_power_on,
> > >       .power_off    = qmp_ufs_disable,
> > > +    .calibrate    = qmp_ufs_phy_calibrate,
> > 
> > Ok so this will break the UFS until patch 5 is applied,
> > breaking bisectability.
> > 
> > Make sure UFS host driver calls calibrate first, and then
> > do the refactor in the PHY driver.
> 
> Hi Neil.
> 
> Thanks for the review. I have taken care of bisecatablity
> compliance by making UFS host driver calls calibrate first
> in latest patch set.

_latest_. So if this patch gets merged first, UFS support will be
broken.

> 
> Regards,
> Nitin
> 
> 
> 
> > 
> > And either all would go in a single tree or either PHY
> > or SCSI maintainer would need to provide an immutable
> > branch for the final merge.
> > 
> > >       .set_mode    = qmp_ufs_set_mode,
> > >       .owner        = THIS_MODULE,
> > >   };
> > > -- 
> > > 2.48.1
> > > 
> > > 
> > 
> 

-- 
With best wishes
Dmitry