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Fri, 09 Jul 2021 15:10:34 -0700 (PDT) Subject: Re: [PATCH v3 4/7] clk: qcom: gdsc: call runtime PM functions for the provider device To: Bjorn Andersson Cc: Andy Gross , Rob Herring , Stephen Boyd , Taniya Das , Jonathan Marek , Michael Turquette , linux-arm-msm@vger.kernel.org, devicetree@vger.kernel.org, linux-clk@vger.kernel.org, Bryan O'Donoghue , Mark Brown , Ulf Hansson , linux-kernel@vger.kernel.org References: <20210709173202.667820-1-dmitry.baryshkov@linaro.org> <20210709173202.667820-5-dmitry.baryshkov@linaro.org> From: Dmitry Baryshkov Message-ID: <613b2f07-ffea-9c65-ebd0-6ad3b4fe10b8@linaro.org> Date: Sat, 10 Jul 2021 01:10:34 +0300 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:78.0) Gecko/20100101 Thunderbird/78.11.0 MIME-Version: 1.0 In-Reply-To: Content-Type: text/plain; charset=utf-8; format=flowed Content-Language: en-GB Content-Transfer-Encoding: 7bit Precedence: bulk List-ID: X-Mailing-List: linux-arm-msm@vger.kernel.org On 09/07/2021 21:54, Bjorn Andersson wrote: > On Fri 09 Jul 12:31 CDT 2021, Dmitry Baryshkov wrote: > >> In order to properly handle runtime PM status of the provider device, >> call pm_runtime_get/pm_runtime_put on the clock controller device. >> >> Signed-off-by: Dmitry Baryshkov >> --- >> drivers/clk/qcom/gdsc.c | 66 ++++++++++++++++++++++++++++++++++++++--- >> drivers/clk/qcom/gdsc.h | 2 ++ >> 2 files changed, 64 insertions(+), 4 deletions(-) >> >> diff --git a/drivers/clk/qcom/gdsc.c b/drivers/clk/qcom/gdsc.c >> index ccd36617d067..6bec31fccb09 100644 >> --- a/drivers/clk/qcom/gdsc.c >> +++ b/drivers/clk/qcom/gdsc.c >> @@ -11,6 +11,7 @@ >> #include >> #include >> #include >> +#include >> #include >> #include >> #include >> @@ -50,6 +51,30 @@ enum gdsc_status { >> GDSC_ON >> }; >> >> +static int gdsc_pm_runtime_get(struct gdsc *sc) >> +{ >> + int ret; >> + >> + if (!sc->rpm_dev) >> + return 0; >> + >> + ret = pm_runtime_get_sync(sc->rpm_dev); >> + if (ret < 0) { >> + pm_runtime_put_noidle(sc->rpm_dev); >> + return ret; >> + } >> + >> + return 0; >> +} >> + >> +static int gdsc_pm_runtime_put(struct gdsc *sc) >> +{ >> + if (!sc->rpm_dev) >> + return 0; >> + >> + return pm_runtime_put_sync(sc->rpm_dev); >> +} >> + >> /* Returns 1 if GDSC status is status, 0 if not, and < 0 on error */ >> static int gdsc_check_status(struct gdsc *sc, enum gdsc_status status) >> { >> @@ -232,9 +257,8 @@ static void gdsc_retain_ff_on(struct gdsc *sc) >> regmap_update_bits(sc->regmap, sc->gdscr, mask, mask); >> } >> >> -static int gdsc_enable(struct generic_pm_domain *domain) >> +static int _gdsc_enable(struct gdsc *sc) >> { >> - struct gdsc *sc = domain_to_gdsc(domain); >> int ret; >> >> if (sc->pwrsts == PWRSTS_ON) >> @@ -290,11 +314,28 @@ static int gdsc_enable(struct generic_pm_domain *domain) >> return 0; >> } >> >> -static int gdsc_disable(struct generic_pm_domain *domain) >> +static int gdsc_enable(struct generic_pm_domain *domain) >> { >> struct gdsc *sc = domain_to_gdsc(domain); >> int ret; >> >> + ret = gdsc_pm_runtime_get(sc); >> + if (ret) >> + return ret; >> + >> + ret = _gdsc_enable(sc); >> + if (ret) { >> + gdsc_pm_runtime_put(sc); > > I presume what you do here is to leave the pm_runtime state of dispcc > active if we succeeded in enabling the gdsc. But the gdsc is a subdomain > of the parent domain, so the framework should take case of its > dependency. > > So the reason for gdsc_pm_runtime_get()/put() in this code path is so > that you can access the dispcc registers, i.e. I think you should > get()/put() regardless of the return value. pm domain code will handle enabling MMCX, so this code is not required strictly speaking. Ulf suggested adding it back, so I followed the suggestion. Maybe I misunderstood his suggestion. putting pm_runtime after gdsc_enable does not sound like a logical case. However it would simplify code a bit. Let me try... > >> + return ret; >> + } >> + >> + return 0; >> +} >> + >> +static int _gdsc_disable(struct gdsc *sc) >> +{ >> + int ret; >> + >> if (sc->pwrsts == PWRSTS_ON) >> return gdsc_assert_reset(sc); >> >> @@ -329,6 +370,18 @@ static int gdsc_disable(struct generic_pm_domain *domain) >> return 0; >> } >> >> +static int gdsc_disable(struct generic_pm_domain *domain) >> +{ >> + struct gdsc *sc = domain_to_gdsc(domain); >> + int ret; >> + > > If the gdsc is found to be on at initialization, the next operation that > will happen is gdsc_disable() and as you didn't activate the pm_runtime > state in gdsc_init() you would in theory get here with registers > unaccessible. > > In practice though, the active gdsc should through the being a subdomain > of the parent domain keep power on for you, so you won't notice this > issue. Nice catch. > > But as above, I think you should wrap _gdsc_disable() in a get()/put() > pair. > >> + ret = _gdsc_disable(sc); >> + if (ret) >> + return ret; >> + >> + return gdsc_pm_runtime_put(sc); >> +} >> + >> static int gdsc_init(struct gdsc *sc) >> { >> u32 mask, val; >> @@ -425,6 +478,8 @@ int gdsc_register(struct gdsc_desc *desc, >> for (i = 0; i < num; i++) { >> if (!scs[i]) >> continue; >> + if (pm_runtime_enabled(dev)) >> + scs[i]->rpm_dev = dev; >> scs[i]->regmap = regmap; >> scs[i]->rcdev = rcdev; >> ret = gdsc_init(scs[i]); >> @@ -486,7 +541,10 @@ void gdsc_unregister(struct gdsc_desc *desc) >> */ >> int gdsc_gx_do_nothing_enable(struct generic_pm_domain *domain) >> { >> + struct gdsc *sc = domain_to_gdsc(domain); >> + >> /* Do nothing but give genpd the impression that we were successful */ >> - return 0; >> + /* Get the runtime PM device only */ >> + return gdsc_pm_runtime_get(sc); > > Per above, if you let the framework deal with the gdsc's dependencies on > the parent domain and you only get()/put() for the sake of dispcc then > you don't need you don't need to do this to keep the subsequent > gdsc_disable() in balance. > >> } >> EXPORT_SYMBOL_GPL(gdsc_gx_do_nothing_enable); >> diff --git a/drivers/clk/qcom/gdsc.h b/drivers/clk/qcom/gdsc.h >> index 5bb396b344d1..a82982df0a55 100644 >> --- a/drivers/clk/qcom/gdsc.h >> +++ b/drivers/clk/qcom/gdsc.h >> @@ -25,6 +25,7 @@ struct reset_controller_dev; >> * @resets: ids of resets associated with this gdsc >> * @reset_count: number of @resets >> * @rcdev: reset controller >> + * @rpm_dev: runtime PM device >> */ >> struct gdsc { >> struct generic_pm_domain pd; >> @@ -58,6 +59,7 @@ struct gdsc { >> >> const char *supply; >> struct regulator *rsupply; >> + struct device *rpm_dev; > > This isn't just the "runtime pm device", it's the device this gdsc is > associated with. So "dev" sounds sufficient to me, but that requires > that you have a separate bool rpm_enabled to remember if > pm_runtime_enabled() was true during probe. > > So unless we need "dev" for something else this might be sufficient. > > Regards, > Bjorn > >> }; >> >> struct gdsc_desc { >> -- >> 2.30.2 >> -- With best wishes Dmitry