Re: [PATCH] phy: qcom: edp: Add runtime PM support

From: Dmitry Baryshkov
Date: Sun Sep 08 2024 - 14:43:25 EST

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On Sun, 8 Sept 2024 at 21:12, Abel Vesa <abel.vesa@xxxxxxxxxx> wrote:
>
> On 24-09-07 20:52:14, Dmitry Baryshkov wrote:
> > On Sat, 7 Sept 2024 at 18:25, Abel Vesa <abel.vesa@xxxxxxxxxx> wrote:
> > >
> > > Enable runtime PM support by adding proper ops which will handle the
> > > clocks and regulators. These resources will now be handled on power_on and
> > > power_off instead of init and exit PHY ops. Also enable these resources on
> > > probe in order to balance out the disabling that is happening right after.
> > > Prevent runtime PM from being ON by default as well.
> > >
> > > Signed-off-by: Abel Vesa <abel.vesa@xxxxxxxxxx>
> > > ---
> > > drivers/phy/qualcomm/phy-qcom-edp.c | 105 ++++++++++++++++++++++++++----------
> > > 1 file changed, 77 insertions(+), 28 deletions(-)
> > >
> > > diff --git a/drivers/phy/qualcomm/phy-qcom-edp.c b/drivers/phy/qualcomm/phy-qcom-edp.c
> > > index da2b32fb5b45..3affeef261bf 100644
> > > --- a/drivers/phy/qualcomm/phy-qcom-edp.c
> > > +++ b/drivers/phy/qualcomm/phy-qcom-edp.c
> > > @@ -192,14 +192,6 @@ static int qcom_edp_phy_init(struct phy *phy)
> > > int ret;
> > > u8 cfg8;
> > >
> > > - ret = regulator_bulk_enable(ARRAY_SIZE(edp->supplies), edp->supplies);
> > > - if (ret)
> > > - return ret;
> > > -
> > > - ret = clk_bulk_prepare_enable(ARRAY_SIZE(edp->clks), edp->clks);
> > > - if (ret)
> > > - goto out_disable_supplies;
> > > -
> > > writel(DP_PHY_PD_CTL_PWRDN | DP_PHY_PD_CTL_AUX_PWRDN |
> > > DP_PHY_PD_CTL_PLL_PWRDN | DP_PHY_PD_CTL_DP_CLAMP_EN,
> > > edp->edp + DP_PHY_PD_CTL);
> > > @@ -246,11 +238,6 @@ static int qcom_edp_phy_init(struct phy *phy)
> > > msleep(20);
> > >
> > > return 0;
> > > -
> > > -out_disable_supplies:
> > > - regulator_bulk_disable(ARRAY_SIZE(edp->supplies), edp->supplies);
> > > -
> > > - return ret;
> > > }
> > >
> > > static int qcom_edp_set_voltages(struct qcom_edp *edp, const struct phy_configure_opts_dp *dp_opts)
> > > @@ -721,6 +708,8 @@ static int qcom_edp_phy_power_on(struct phy *phy)
> > > u32 val;
> > > u8 cfg1;
> > >
> > > + pm_runtime_get_sync(&phy->dev);
> > > +
> > > ret = edp->cfg->ver_ops->com_power_on(edp);
> > > if (ret)
> > > return ret;
> > > @@ -841,6 +830,8 @@ static int qcom_edp_phy_power_off(struct phy *phy)
> > >
> > > writel(DP_PHY_PD_CTL_PSR_PWRDN, edp->edp + DP_PHY_PD_CTL);
> > >
> > > + pm_runtime_put(&phy->dev);
> > > +
> > > return 0;
> > > }
> > >
> > > @@ -856,23 +847,12 @@ static int qcom_edp_phy_set_mode(struct phy *phy, enum phy_mode mode, int submod
> > > return 0;
> > > }
> > >
> > > -static int qcom_edp_phy_exit(struct phy *phy)
> > > -{
> > > - struct qcom_edp *edp = phy_get_drvdata(phy);
> > > -
> > > - clk_bulk_disable_unprepare(ARRAY_SIZE(edp->clks), edp->clks);
> > > - regulator_bulk_disable(ARRAY_SIZE(edp->supplies), edp->supplies);
> > > -
> > > - return 0;
> > > -}
> > > -
> > > static const struct phy_ops qcom_edp_ops = {
> > > .init = qcom_edp_phy_init,
> > > .configure = qcom_edp_phy_configure,
> > > .power_on = qcom_edp_phy_power_on,
> > > .power_off = qcom_edp_phy_power_off,
> > > .set_mode = qcom_edp_phy_set_mode,
> > > - .exit = qcom_edp_phy_exit,
> > > .owner = THIS_MODULE,
> > > };
> > >
> > > @@ -1036,6 +1016,32 @@ static int qcom_edp_clks_register(struct qcom_edp *edp, struct device_node *np)
> > > return devm_of_clk_add_hw_provider(edp->dev, of_clk_hw_onecell_get, data);
> > > }
> > >
> > > +static int __maybe_unused qcom_edp_runtime_suspend(struct device *dev)
> > > +{
> > > + struct qcom_edp *edp = dev_get_drvdata(dev);
> > > +
> > > + dev_err(dev, "Suspending DP phy\n");
> >
> > Debug leftovers?
>
> Well, I should've made those dev_vdbg instead.
>
> >
> > > +
> > > + clk_bulk_disable_unprepare(ARRAY_SIZE(edp->clks), edp->clks);
> > > + regulator_bulk_disable(ARRAY_SIZE(edp->supplies), edp->supplies);
> > > +
> > > + return 0;
> > > +}
> > > +
> > > +static int __maybe_unused qcom_edp_runtime_resume(struct device *dev)
> > > +{
> > > + struct qcom_edp *edp = dev_get_drvdata(dev);
> > > + int ret;
> > > +
> > > + dev_err(dev, "Resuming DP phy\n");
> >
> > Debug leftovers?
> >
>
> See above.
>
> > > +
> > > + ret = regulator_bulk_enable(ARRAY_SIZE(edp->supplies), edp->supplies);
> > > + if (ret)
> > > + return ret;
> > > +
> > > + return clk_bulk_prepare_enable(ARRAY_SIZE(edp->clks), edp->clks);
> >
> > Missing error handling
> >
>
> Yep, will fix.
>
> > > +}
> > > +
> > > static int qcom_edp_phy_probe(struct platform_device *pdev)
> > > {
> > > struct phy_provider *phy_provider;
> > > @@ -1091,20 +1097,57 @@ static int qcom_edp_phy_probe(struct platform_device *pdev)
> > > return ret;
> > > }
> > >
> > > - ret = qcom_edp_clks_register(edp, pdev->dev.of_node);
> > > - if (ret)
> > > + ret = regulator_bulk_enable(ARRAY_SIZE(edp->supplies), edp->supplies);
> > > + if (ret) {
> > > + dev_err(dev, "failed to enable regulators, err=%d\n", ret);
> > > return ret;
> > > + }
> > > +
> > > + ret = clk_bulk_prepare_enable(ARRAY_SIZE(edp->clks), edp->clks);
> > > + if (ret) {
> > > + dev_err(dev, "failed to enable clocks, err=%d\n", ret);
> > > + goto err_disable_regulators;
> > > + }
> >
> > Please use pm_runtime_get_sync() instead().
> >
>
> So let me explain how I thought this through first. This DP PHY is
> usually used on platforms where display is left enabled by the
> bootloader. So doing pm_runtime_get_sync would mean we increment the
> device's usage counter while it is known to be already enabled, even if
> genpd doesn't consider it so. So doing set_active instead would be more
> accurate. Now, for the regulator and clock generic frameworks, that
> seemed OK to do at the time. Now I can see that the same argument can be
> made for those as well. So I'm thinking maybe I just drop the enable
> here and don't do _get_sync, but rather rely on the resume being done
> on power on instead.

Please don't rely on the bootloader. The device should be in the
resumed state when registering clocks. Also devm_pm_runtime_enable()
should also be called before, so that the CCF makes note of PM being
enabled.

>
> > > +
> > > + ret = qcom_edp_clks_register(edp, pdev->dev.of_node);
> > > + if (ret) {
> > > + dev_err(dev, "failed to register PHY clocks, err=%d\n", ret);
> > > + goto err_disable_clocks;
> > > + }
> > >
> > > edp->phy = devm_phy_create(dev, pdev->dev.of_node, &qcom_edp_ops);
> > > if (IS_ERR(edp->phy)) {
> > > dev_err(dev, "failed to register phy\n");
> > > - return PTR_ERR(edp->phy);
> > > + ret = PTR_ERR(edp->phy);
> > > + goto err_disable_clocks;
> > > }
> > >
> > > + pm_runtime_set_active(dev);
> > > + ret = devm_pm_runtime_enable(dev);
> >
> > If this handles earlier, you don't need to call pm_runtime_set_active() manually
> >
>
> Enable and set_active are two separate things. Maybe I'm
> misunderstanding your comment.

Yeah, I wrote something strange here. I meant that if enable is called
earlier and then if the device is resumed, there is no need to call
set_active.

>
> > > + if (ret)
> > > + goto err_disable_clocks;
> > > + /*
> > > + * Prevent runtime pm from being ON by default. Users can enable
> > > + * it using power/control in sysfs.
> >
> > why?
> >
>
> OK, so this is a tricky one. If there is any platform out there that
> makes use of this PHY but the resources are not properly described, we
> might get in trouble. So I was thinking that maybe we don't risk that
> but let the user enable it via sysfs. That way, this patch will not
> break by default such platforms.

If the platform doesn't describe resources, it is broken, there is no
need to support it.
>
> Also, this would be in line with the rest of the other Qcom PHYs.

I think it's a bit of a cargo cult. Such code was added in 2018 and
then it was c&p'ed since that time.

>
> > > + */
> > > + pm_runtime_forbid(dev);
> > > +
> > > + dev_set_drvdata(dev, edp);
> > > phy_set_drvdata(edp->phy, edp);
> > >
> > > phy_provider = devm_of_phy_provider_register(dev, of_phy_simple_xlate);
> > > - return PTR_ERR_OR_ZERO(phy_provider);
> > > + if (IS_ERR(phy_provider))
> > > + goto err_disable_clocks;
> > > +
> > > + return 0;
> > > +
> > > +err_disable_clocks:
> > > + clk_bulk_disable_unprepare(ARRAY_SIZE(edp->clks), edp->clks);
> > > +
> > > +err_disable_regulators:
> > > + regulator_bulk_disable(ARRAY_SIZE(edp->supplies), edp->supplies);
> >
> > Ideally this should be handled by pm_runtime. Or at least by pm_runtime_put().
>
> Will drop entirely. Again, lets not enable anything on probe for now.

NAK.

>
> >
> > > +
> > > + return ret;
> > > }
> > >
> > > static const struct of_device_id qcom_edp_phy_match_table[] = {
> > > @@ -1117,10 +1160,16 @@ static const struct of_device_id qcom_edp_phy_match_table[] = {
> > > };
> > > MODULE_DEVICE_TABLE(of, qcom_edp_phy_match_table);
> > >
> > > +static const struct dev_pm_ops qcom_edp_pm_ops = {
> > > + SET_RUNTIME_PM_OPS(qcom_edp_runtime_suspend,
> > > + qcom_edp_runtime_resume, NULL)
> > > +};
> > > +
> > > static struct platform_driver qcom_edp_phy_driver = {
> > > .probe = qcom_edp_phy_probe,
> > > .driver = {
> > > .name = "qcom-edp-phy",
> > > + .pm = &qcom_edp_pm_ops,
> > > .of_match_table = qcom_edp_phy_match_table,
> > > },
> > > };
> > >
> > > ---
> > > base-commit: 9aaeb87ce1e966169a57f53a02ba05b30880ffb8
> > > change-id: 20240907-phy-qcom-edp-enable-runtime-pm-6fad07af8947
> > >
> > > Best regards,
> > > --
> > > Abel Vesa <abel.vesa@xxxxxxxxxx>
> > >
> >
> >
> > --
> > With best wishes
> > Dmitry

--
With best wishes
Dmitry

Next message: Sam James: "[PATCH] tools: drop nonsensical -O6"
Previous message: Dennis Lam: "[PATCH] docs:filesystem: fix mispelled words on autofs page"
In reply to: Abel Vesa: "Re: [PATCH] phy: qcom: edp: Add runtime PM support"
Next in thread: Abel Vesa: "Re: [PATCH] phy: qcom: edp: Add runtime PM support"
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