Re: [PATCH V5 09/11] scsi: ufs: qcom : Refactor phy_power_on/off calls

Manivannan Sadhasivam
2025-05-22T08:55:43Z

On Thu, May 22, 2025 at 03:10:48AM +0530, Nitin Rawat wrote:
>
>
> On 5/21/2025 7:27 PM, Manivannan Sadhasivam wrote:
> > On Thu, May 15, 2025 at 09:57:20PM +0530, Nitin Rawat wrote:
> > > Commit 3f6d1767b1a0 ("phy: ufs-qcom: Refactor all init steps into
> > > phy_poweron") removes the phy_power_on/off from ufs_qcom_setup_clocks
> >
> > s/removes/moved
>
> Sure, will address in next patchset.
>
> >
> > > to suspend/resume func.
> > >
> > > To have a better power saving, remove the phy_power_on/off calls from
> > > resume/suspend path and put them back to ufs_qcom_setup_clocks, so that
> > > PHY regulators & clks can be turned on/off along with UFS's clocks.
> > >
> > > Since phy phy_power_on is separated out from phy calibrate, make
> > > separate calls to phy_power_on and phy_calibrate calls from ufs qcom
> > > driver.
> > >
> >
> > This patch is not calling phy_calibrate().
>
> updated commit text to remove phy_Calibrate from commit text
>
> >
> > > Co-developed-by: Can Guo <quic_cang@quicinc.com>
> > > Signed-off-by: Can Guo <quic_cang@quicinc.com>
> > > Signed-off-by: Nitin Rawat <quic_nitirawa@quicinc.com>
> > > ---
> > > drivers/ufs/host/ufs-qcom.c | 61 ++++++++++++++++++-------------------
> > > 1 file changed, 29 insertions(+), 32 deletions(-)
> > >
> >
> > [...]
> >
> > > 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;
> > > /*
> > > * In case ufs_qcom_init() is not yet done, simply ignore.
> > > @@ -1157,10 +1141,22 @@ 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);
> > > + if (err) {
> > > + dev_err(hba->dev, "phy power off failed, ret=%d\n", err);
> > > + return err;
> > > + }
> > > }
> > > break;
> > > case POST_CHANGE:
> > > if (on) {
> > > + err = phy_power_on(phy);
> > > + if (err) {
> > > + dev_err(hba->dev, "phy power on failed, ret = %d\n", err);
> > > + return err;
> > > + }
> > > +
> > > /* enable the device ref clock for HS mode*/
> > > if (ufshcd_is_hs_mode(&hba->pwr_info))
> > > ufs_qcom_dev_ref_clk_ctrl(host, true);
> > > @@ -1343,9 +1339,10 @@ 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(host->generic_phy);
> > > + phy_power_off(phy);
> >
> > This change is not at all needed.
>
> In the current code, PHY resources (clocks and rails) remain active even
> when the link is in a hibernate state and all controller clocks are off.
> This results in a significant power penalty and can prevent CX power
> collapse.
>
> These rails and clocks are only turned off when a system suspend is
> triggered, and even then, only at SPM level 5 where the link is turned off.
> This approach is not power-efficient.
>
> As part of this series, the code that enables/disables the PHY's regulators
> and clocks is now confined to the phy_power_on and phy_power_off calls, with
> the rest moved to the calibration phase.
>
> Therefore, we are invoking the phy_power_off and phy_power_on calls from
> ufs_qcom_setup_clocks, ensuring that the PHY's regulators and clocks can be
> turned on/off along with the UFS clocks, thereby achieving power savings.
>
> Therefore, this patch is the cornerstone of this series.
>

I did not question the patch, but just the change that you did in the
ufs_qcom_exit() function. You added a local variable for 'host->generic_phy',
which is not related to this patch.

- Mani

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