Messages in this thread | | | Subject | Re: [PATCH v3 3/7] clk: qcom: gdsc: enable optional power domain support | From | Dmitry Baryshkov <> | Date | Sat, 10 Jul 2021 00:28:54 +0300 |
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On 09/07/2021 21:38, Bjorn Andersson wrote: > On Fri 09 Jul 12:31 CDT 2021, Dmitry Baryshkov wrote: > >> On sm8250 dispcc and videocc registers are powered up by the MMCX power >> domain. Currently we use a regulator to enable this domain on demand, >> however this has some consequences, as genpd code is not reentrant. >> >> Teach Qualcomm clock controller code about setting up runtime PM and >> using specified for gdsc powerup. >> >> Signed-off-by: Dmitry Baryshkov <dmitry.baryshkov@linaro.org> >> --- >> drivers/clk/qcom/common.c | 37 +++++++++++++++++++++++++++++++------ >> drivers/clk/qcom/gdsc.c | 4 ++++ >> 2 files changed, 35 insertions(+), 6 deletions(-) >> >> diff --git a/drivers/clk/qcom/common.c b/drivers/clk/qcom/common.c >> index 60d2a78d1395..43d8f8feeb3c 100644 >> --- a/drivers/clk/qcom/common.c >> +++ b/drivers/clk/qcom/common.c >> @@ -10,6 +10,7 @@ >> #include <linux/clk-provider.h> >> #include <linux/reset-controller.h> >> #include <linux/of.h> >> +#include <linux/pm_runtime.h> >> >> #include "common.h" >> #include "clk-rcg.h" >> @@ -224,6 +225,11 @@ static struct clk_hw *qcom_cc_clk_hw_get(struct of_phandle_args *clkspec, >> return cc->rclks[idx] ? &cc->rclks[idx]->hw : NULL; >> } >> >> +static void qcom_cc_pm_runtime_disable(void *data) >> +{ >> + pm_runtime_disable(data); >> +} >> + >> int qcom_cc_really_probe(struct platform_device *pdev, >> const struct qcom_cc_desc *desc, struct regmap *regmap) >> { >> @@ -241,6 +247,18 @@ int qcom_cc_really_probe(struct platform_device *pdev, >> if (!cc) >> return -ENOMEM; >> >> + pm_runtime_enable(dev); > > In turingcc-qcs404.c I'm using pm_runtime to have the clock framework > ensure that the iface clock is enabled during clock operations, so this > will result in a "unbalanced enable" warning.
And later I register the disabler:
ret = devm_add_action_or_reset(dev, qcom_cc_pm_runtime_disable, dev);
You might want to add this to qcs404 code.
> >> + ret = pm_runtime_get_sync(dev); > > I don't think you should wrap the entire initialization in a > pm_runtime_get_sync()/put() region. Instead follow the clock framework > and wrap gdsc initialization that needs to touch the hardware in:
Init should be wrapped in the pm_runtime_get/put calls, so that the MMCX domain is on through the fall init sequence. Otherwise it can get turned off during it, boom, failed register access and reboot.
> > if (pm_runtime_enabled()) > pm_runtime_get_sync();
I don't think it's worth doing that. Having single lock for the whole init sequence is safer (and cleaner).
If you check other pm-enabled drivers, they would either call pm_runtime_enable at the end of the probe or get_sync in the beginning of the probe and put_FOO in the end. In this driver calling pm_runtime_enable() at the end of the probe function will not work, since this way clk subsystem will not pick up the device for runtime power management (as pm_runtime_enabled() would return false).
> > I do however think that as of this patch, when probe returns MMCX might > very well be turned off, as the only user (this driver) has pm_runtime > enabled and it's idle. So I think you should introduce the > pm_runtime_get()/put() in the gdsc functions before this patch.
Maybe I'd just squash them together.
> > > To summarize, I think you should rely on the individual clock drivers to > pm_runtime_enable()/disable(). > >> + if (ret < 0) { >> + pm_runtime_put(dev); >> + pm_runtime_disable(dev); >> + return ret; >> + } >> + >> + ret = devm_add_action_or_reset(dev, qcom_cc_pm_runtime_disable, dev); >> + if (ret) >> + goto err; >> + >> reset = &cc->reset; >> reset->rcdev.of_node = dev->of_node; >> reset->rcdev.ops = &qcom_reset_ops; >> @@ -251,7 +269,7 @@ int qcom_cc_really_probe(struct platform_device *pdev, >> >> ret = devm_reset_controller_register(dev, &reset->rcdev); >> if (ret) >> - return ret; >> + goto err; >> >> if (desc->gdscs && desc->num_gdscs) { >> scd = devm_kzalloc(dev, sizeof(*scd), GFP_KERNEL); >> @@ -262,11 +280,11 @@ int qcom_cc_really_probe(struct platform_device *pdev, >> scd->num = desc->num_gdscs; >> ret = gdsc_register(scd, &reset->rcdev, regmap); >> if (ret) >> - return ret; >> + goto err; >> ret = devm_add_action_or_reset(dev, qcom_cc_gdsc_unregister, >> scd); >> if (ret) >> - return ret; >> + goto err; >> } >> >> cc->rclks = rclks; >> @@ -277,7 +295,7 @@ int qcom_cc_really_probe(struct platform_device *pdev, >> for (i = 0; i < num_clk_hws; i++) { >> ret = devm_clk_hw_register(dev, clk_hws[i]); >> if (ret) >> - return ret; >> + goto err; >> } >> >> for (i = 0; i < num_clks; i++) { >> @@ -286,14 +304,21 @@ int qcom_cc_really_probe(struct platform_device *pdev, >> >> ret = devm_clk_register_regmap(dev, rclks[i]); >> if (ret) >> - return ret; >> + goto err; >> } >> >> ret = devm_of_clk_add_hw_provider(dev, qcom_cc_clk_hw_get, cc); >> if (ret) >> - return ret; >> + goto err; >> + >> + pm_runtime_put(dev); >> >> return 0; >> + >> +err: >> + pm_runtime_put(dev); >> + >> + return ret; >> } >> EXPORT_SYMBOL_GPL(qcom_cc_really_probe); >> >> diff --git a/drivers/clk/qcom/gdsc.c b/drivers/clk/qcom/gdsc.c >> index 51ed640e527b..ccd36617d067 100644 >> --- a/drivers/clk/qcom/gdsc.c >> +++ b/drivers/clk/qcom/gdsc.c >> @@ -439,6 +439,8 @@ int gdsc_register(struct gdsc_desc *desc, >> continue; >> if (scs[i]->parent) >> pm_genpd_add_subdomain(scs[i]->parent, &scs[i]->pd); >> + else if (!IS_ERR_OR_NULL(dev->pm_domain)) >> + pm_genpd_add_subdomain(pd_to_genpd(dev->pm_domain), &scs[i]->pd); > > Nice, I didn't know that we could fish it out of the dev. > > Regards, > Bjorn > >> } >> >> return of_genpd_add_provider_onecell(dev->of_node, data); >> @@ -457,6 +459,8 @@ void gdsc_unregister(struct gdsc_desc *desc) >> continue; >> if (scs[i]->parent) >> pm_genpd_remove_subdomain(scs[i]->parent, &scs[i]->pd); >> + else if (!IS_ERR_OR_NULL(dev->pm_domain)) >> + pm_genpd_remove_subdomain(pd_to_genpd(dev->pm_domain), &scs[i]->pd); >> } >> of_genpd_del_provider(dev->of_node); >> } >> -- >> 2.30.2 >>
-- With best wishes Dmitry
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