| Message ID | 20210708120656.663851-4-thara.gopinath@linaro.org |
|---|---|
| State | New |
| Headers | show |
| Series | Introduce LMh driver for Qualcomm SoCs | expand |
On 08-07-21, 08:06, Thara Gopinath wrote: > static int qcom_cpufreq_hw_cpu_init(struct cpufreq_policy *policy) > { > struct platform_device *pdev = cpufreq_get_driver_data(); > @@ -370,6 +480,10 @@ static int qcom_cpufreq_hw_cpu_init(struct cpufreq_policy *policy) > dev_warn(cpu_dev, "failed to enable boost: %d\n", ret); > } > > + ret = qcom_cpufreq_hw_lmh_init(policy, index); You missed unregistering EM here (which is also missing from exit, which you need to fix first in a separate patch). > + if (ret) > + goto error; > + > return 0; > error: > kfree(data); > @@ -389,6 +503,10 @@ static int qcom_cpufreq_hw_cpu_exit(struct cpufreq_policy *policy) > > dev_pm_opp_remove_all_dynamic(cpu_dev); > dev_pm_opp_of_cpumask_remove_table(policy->related_cpus); > + if (data->lmh_dcvs_irq > 0) { > + devm_free_irq(cpu_dev, data->lmh_dcvs_irq, data); Why using devm variants here and while requesting the irq ? > + cancel_delayed_work_sync(&data->lmh_dcvs_poll_work); > + } Please move this to qcom_cpufreq_hw_lmh_exit() or something. Now with sequence of disabling interrupt, etc, I see a potential problem. CPU0 CPU1 qcom_cpufreq_hw_cpu_exit() -> devm_free_irq(); qcom_lmh_dcvs_poll() -> qcom_lmh_dcvs_notify() -> enable_irq() -> cancel_delayed_work_sync(); What will happen if enable_irq() gets called after freeing the irq ? Not sure, but it looks like you will hit this then from manage.c: WARN(!desc->irq_data.chip, KERN_ERR "enable_irq before setup/request_irq: irq %u\n", irq)) ? You got a chicken n egg problem :) -- viresh
On 7/9/21 2:46 AM, Viresh Kumar wrote: > On 08-07-21, 08:06, Thara Gopinath wrote: >> static int qcom_cpufreq_hw_cpu_init(struct cpufreq_policy *policy) >> { >> struct platform_device *pdev = cpufreq_get_driver_data(); >> @@ -370,6 +480,10 @@ static int qcom_cpufreq_hw_cpu_init(struct cpufreq_policy *policy) >> dev_warn(cpu_dev, "failed to enable boost: %d\n", ret); >> } >> >> + ret = qcom_cpufreq_hw_lmh_init(policy, index); > > You missed unregistering EM here (which is also missing from exit, > which you need to fix first in a separate patch). Hi! So how exactly do you do this? I checked other users of the api and I do not see any free. I would say if needed, it should be a separate patch and outside of this series. > >> + if (ret) >> + goto error; >> + >> return 0; >> error: >> kfree(data); >> @@ -389,6 +503,10 @@ static int qcom_cpufreq_hw_cpu_exit(struct cpufreq_policy *policy) >> >> dev_pm_opp_remove_all_dynamic(cpu_dev); >> dev_pm_opp_of_cpumask_remove_table(policy->related_cpus); >> + if (data->lmh_dcvs_irq > 0) { >> + devm_free_irq(cpu_dev, data->lmh_dcvs_irq, data); > > Why using devm variants here and while requesting the irq ? > >> + cancel_delayed_work_sync(&data->lmh_dcvs_poll_work); >> + } > > Please move this to qcom_cpufreq_hw_lmh_exit() or something. Ok. > > Now with sequence of disabling interrupt, etc, I see a potential > problem. > > CPU0 CPU1 > > qcom_cpufreq_hw_cpu_exit() > -> devm_free_irq(); > qcom_lmh_dcvs_poll() > -> qcom_lmh_dcvs_notify() > -> enable_irq() > > -> cancel_delayed_work_sync(); > > > What will happen if enable_irq() gets called after freeing the irq ? > Not sure, but it looks like you will hit this then from manage.c: > > WARN(!desc->irq_data.chip, KERN_ERR "enable_irq before > setup/request_irq: irq %u\n", irq)) > > ? > > You got a chicken n egg problem :) Yes indeed! But also it is a very rare chicken and egg problem. The scenario here is that the cpus are busy and running load causing a thermal overrun and lmh is engaged. At the same time for this issue to be hit the cpu is trying to exit/disable cpufreq. Calling cancel_delayed_work_sync first could solve this issue, right ? cancel_delayed_work_sync guarantees the work not to be pending even if it requeues itself on return. So once the delayed work is cancelled, the interrupts can be safely disabled. Thoughts ? >
On Thu 08 Jul 07:06 CDT 2021, Thara Gopinath wrote: > Add interrupt support to notify the kernel of h/w initiated frequency > throttling by LMh. Convey this to scheduler via thermal presssure > interface. > > Signed-off-by: Thara Gopinath <thara.gopinath@linaro.org> > --- > > v2->v3: > - Cosmetic fixes from review comments on the list. > - Moved all LMh initializations to qcom_cpufreq_hw_lmh_init. > - Added freeing of LMh interrupt and cancelling the polling worker to > qcom_cpufreq_hw_cpu_exit as per Viresh's suggestion. > - LMh interrupts are now tied to cpu dev and not cpufreq dev. This will be > useful for further generation of SoCs where the same interrupt signals > multiple cpu clusters. > > v1->v2: > - Introduced qcom_cpufreq_hw_lmh_init to consolidate LMh related initializations > as per Viresh's review comment. > - Moved the piece of code restarting polling/re-enabling LMh interrupt to > qcom_lmh_dcvs_notify therby simplifying isr and timer callback as per Viresh's > suggestion. > - Droped cpus from qcom_cpufreq_data and instead using cpus from cpufreq_policy in > qcom_lmh_dcvs_notify as per Viresh's review comment. > - Dropped dt property qcom,support-lmh as per Bjorn's suggestion. > - Other minor/cosmetic fixes > > drivers/cpufreq/qcom-cpufreq-hw.c | 118 ++++++++++++++++++++++++++++++ > 1 file changed, 118 insertions(+) > > diff --git a/drivers/cpufreq/qcom-cpufreq-hw.c b/drivers/cpufreq/qcom-cpufreq-hw.c > index f86859bf76f1..bb5fc700d913 100644 > --- a/drivers/cpufreq/qcom-cpufreq-hw.c > +++ b/drivers/cpufreq/qcom-cpufreq-hw.c > @@ -7,6 +7,7 @@ > #include <linux/cpufreq.h> > #include <linux/init.h> > #include <linux/interconnect.h> > +#include <linux/interrupt.h> > #include <linux/kernel.h> > #include <linux/module.h> > #include <linux/of_address.h> > @@ -22,10 +23,13 @@ > #define CLK_HW_DIV 2 > #define LUT_TURBO_IND 1 > > +#define HZ_PER_KHZ 1000 > + > struct qcom_cpufreq_soc_data { > u32 reg_enable; > u32 reg_freq_lut; > u32 reg_volt_lut; > + u32 reg_current_vote; > u32 reg_perf_state; > u8 lut_row_size; > }; > @@ -33,7 +37,10 @@ struct qcom_cpufreq_soc_data { > struct qcom_cpufreq_data { > void __iomem *base; > struct resource *res; > + struct delayed_work lmh_dcvs_poll_work; How about dropping "lmh" from this variable name? Perhaps "throttle_work" or something like that? > const struct qcom_cpufreq_soc_data *soc_data; > + struct cpufreq_policy *policy; > + int lmh_dcvs_irq; throttle_irq ? > }; > > static unsigned long cpu_hw_rate, xo_rate; > @@ -251,10 +258,84 @@ static void qcom_get_related_cpus(int index, struct cpumask *m) > } > } > > +static inline unsigned long qcom_lmh_vote_to_freq(u32 val) > +{ > + return (val & 0x3FF) * 19200; > +} > + > +static void qcom_lmh_dcvs_notify(struct qcom_cpufreq_data *data) > +{ > + struct cpufreq_policy *policy = data->policy; > + struct dev_pm_opp *opp; > + struct device *dev; > + unsigned long max_capacity, capacity, freq_hz, throttled_freq; > + unsigned int val, freq; > + > + /* > + * Get the h/w throttled frequency, normalize it using the > + * registered opp table and use it to calculate thermal pressure. > + */ > + val = readl_relaxed(data->base + data->soc_data->reg_current_vote); I would find it cleaner to move the readl() into the helper function, as you don't care about the register value, only the resulting frequency. > + freq = qcom_lmh_vote_to_freq(val); > + freq_hz = freq * HZ_PER_KHZ; > + > + dev = get_cpu_device(cpumask_first(policy->cpus)); > + opp = dev_pm_opp_find_freq_floor(dev, &freq_hz); > + if (IS_ERR(opp) && PTR_ERR(opp) == -ERANGE) > + opp = dev_pm_opp_find_freq_ceil(dev, &freq_hz); > + > + throttled_freq = freq_hz / HZ_PER_KHZ; > + > + /* Update thermal pressure */ > + > + max_capacity = arch_scale_cpu_capacity(cpumask_first(policy->cpus)); > + capacity = throttled_freq * max_capacity; > + capacity /= policy->cpuinfo.max_freq; Perhaps, to avoid overflows if this is ever used on a 32-bit platform use: mult_frac(max_capacity, throttled_freq, policy->cpuinfo.max_freq) > + > + /* Don't pass boost capacity to scheduler */ > + if (capacity > max_capacity) > + capacity = max_capacity; > + > + arch_set_thermal_pressure(policy->cpus, max_capacity - capacity); > + > + /* > + * If h/w throttled frequency is higher than what cpufreq has requested for, stop > + * polling and switch back to interrupt mechanism > + */ > + > + if (throttled_freq >= qcom_cpufreq_hw_get(cpumask_first(policy->cpus))) > + /* Clear the existing interrupts and enable it back */ > + enable_irq(data->lmh_dcvs_irq); > + else > + mod_delayed_work(system_highpri_wq, &data->lmh_dcvs_poll_work, > + msecs_to_jiffies(10)); > +} > + > +static void qcom_lmh_dcvs_poll(struct work_struct *work) > +{ > + struct qcom_cpufreq_data *data; > + > + data = container_of(work, struct qcom_cpufreq_data, lmh_dcvs_poll_work.work); > + > + qcom_lmh_dcvs_notify(data); > +} > + > +static irqreturn_t qcom_lmh_dcvs_handle_irq(int irq, void *data) > +{ > + struct qcom_cpufreq_data *c_data = data; > + > + /* Disable interrupt and enable polling */ > + disable_irq_nosync(c_data->lmh_dcvs_irq); > + qcom_lmh_dcvs_notify(c_data); > + > + return 0; > +} > + > static const struct qcom_cpufreq_soc_data qcom_soc_data = { > .reg_enable = 0x0, > .reg_freq_lut = 0x110, > .reg_volt_lut = 0x114, > + .reg_current_vote = 0x704, > .reg_perf_state = 0x920, > .lut_row_size = 32, > }; > @@ -274,6 +355,35 @@ static const struct of_device_id qcom_cpufreq_hw_match[] = { > }; > MODULE_DEVICE_TABLE(of, qcom_cpufreq_hw_match); > > +static int qcom_cpufreq_hw_lmh_init(struct cpufreq_policy *policy, int index) > +{ > + struct qcom_cpufreq_data *data = policy->driver_data; > + struct platform_device *pdev = cpufreq_get_driver_data(); > + struct device *cpu_dev = get_cpu_device(policy->cpu); > + char irq_name[15]; > + int ret; > + > + /* > + * Look for LMh interrupt. If no interrupt line is specified / > + * if there is an error, allow cpufreq to be enabled as usual. > + */ > + data->lmh_dcvs_irq = platform_get_irq(pdev, index); > + if (data->lmh_dcvs_irq <= 0) > + return data->lmh_dcvs_irq == -EPROBE_DEFER ? -EPROBE_DEFER : 0; > + > + snprintf(irq_name, sizeof(irq_name), "dcvsh-irq-%u", policy->cpu); > + ret = devm_request_irq(cpu_dev, data->lmh_dcvs_irq, qcom_lmh_dcvs_handle_irq, > + 0, irq_name, data); > + if (ret) { > + dev_err(&pdev->dev, "Error %d registering irq %x\n", ret, data->lmh_dcvs_irq); The irq number here won't have any meaning, and %x wouldn't be suitable. How about ..."Error registering %s: %d\n", irq_name, ret); ? > + return 0; This sounds like a problem, wouldn't it be suitable to treat it as a problem? > + } > + data->policy = policy; Afaict, no one is going to access data->policy unless devm_request_irq() succeeds and if it does and the interrupt fires immediately it would be too late to set it here. So better move it earlier. > + INIT_DEFERRABLE_WORK(&data->lmh_dcvs_poll_work, qcom_lmh_dcvs_poll); What if the interrupt fires before you initialize the work? Better move this higher up. > + > + return 0; > +} > + > static int qcom_cpufreq_hw_cpu_init(struct cpufreq_policy *policy) > { > struct platform_device *pdev = cpufreq_get_driver_data(); > @@ -370,6 +480,10 @@ static int qcom_cpufreq_hw_cpu_init(struct cpufreq_policy *policy) > dev_warn(cpu_dev, "failed to enable boost: %d\n", ret); > } > > + ret = qcom_cpufreq_hw_lmh_init(policy, index); > + if (ret) > + goto error; > + > return 0; > error: > kfree(data); > @@ -389,6 +503,10 @@ static int qcom_cpufreq_hw_cpu_exit(struct cpufreq_policy *policy) > > dev_pm_opp_remove_all_dynamic(cpu_dev); > dev_pm_opp_of_cpumask_remove_table(policy->related_cpus); > + if (data->lmh_dcvs_irq > 0) { > + devm_free_irq(cpu_dev, data->lmh_dcvs_irq, data); As init/exit are called multiple times you should avoid the devm variants. Regards, Bjorn > + cancel_delayed_work_sync(&data->lmh_dcvs_poll_work); > + } > kfree(policy->freq_table); > kfree(data); > iounmap(base); > -- > 2.25.1 >
On 7/10/21 12:57 AM, Bjorn Andersson wrote: > On Thu 08 Jul 07:06 CDT 2021, Thara Gopinath wrote: > >> Add interrupt support to notify the kernel of h/w initiated frequency >> throttling by LMh. Convey this to scheduler via thermal presssure >> interface. >> >> Signed-off-by: Thara Gopinath <thara.gopinath@linaro.org> >> --- >> >> v2->v3: >> - Cosmetic fixes from review comments on the list. >> - Moved all LMh initializations to qcom_cpufreq_hw_lmh_init. >> - Added freeing of LMh interrupt and cancelling the polling worker to >> qcom_cpufreq_hw_cpu_exit as per Viresh's suggestion. >> - LMh interrupts are now tied to cpu dev and not cpufreq dev. This will be >> useful for further generation of SoCs where the same interrupt signals >> multiple cpu clusters. >> >> v1->v2: >> - Introduced qcom_cpufreq_hw_lmh_init to consolidate LMh related initializations >> as per Viresh's review comment. >> - Moved the piece of code restarting polling/re-enabling LMh interrupt to >> qcom_lmh_dcvs_notify therby simplifying isr and timer callback as per Viresh's >> suggestion. >> - Droped cpus from qcom_cpufreq_data and instead using cpus from cpufreq_policy in >> qcom_lmh_dcvs_notify as per Viresh's review comment. >> - Dropped dt property qcom,support-lmh as per Bjorn's suggestion. >> - Other minor/cosmetic fixes >> >> drivers/cpufreq/qcom-cpufreq-hw.c | 118 ++++++++++++++++++++++++++++++ >> 1 file changed, 118 insertions(+) >> >> diff --git a/drivers/cpufreq/qcom-cpufreq-hw.c b/drivers/cpufreq/qcom-cpufreq-hw.c >> index f86859bf76f1..bb5fc700d913 100644 >> --- a/drivers/cpufreq/qcom-cpufreq-hw.c >> +++ b/drivers/cpufreq/qcom-cpufreq-hw.c >> @@ -7,6 +7,7 @@ >> #include <linux/cpufreq.h> >> #include <linux/init.h> >> #include <linux/interconnect.h> >> +#include <linux/interrupt.h> >> #include <linux/kernel.h> >> #include <linux/module.h> >> #include <linux/of_address.h> >> @@ -22,10 +23,13 @@ >> #define CLK_HW_DIV 2 >> #define LUT_TURBO_IND 1 >> >> +#define HZ_PER_KHZ 1000 >> + >> struct qcom_cpufreq_soc_data { >> u32 reg_enable; >> u32 reg_freq_lut; >> u32 reg_volt_lut; >> + u32 reg_current_vote; >> u32 reg_perf_state; >> u8 lut_row_size; >> }; >> @@ -33,7 +37,10 @@ struct qcom_cpufreq_soc_data { >> struct qcom_cpufreq_data { >> void __iomem *base; >> struct resource *res; >> + struct delayed_work lmh_dcvs_poll_work; > > How about dropping "lmh" from this variable name? > > Perhaps "throttle_work" or something like that? > >> const struct qcom_cpufreq_soc_data *soc_data; >> + struct cpufreq_policy *policy; >> + int lmh_dcvs_irq; > > throttle_irq ? sounds good! > >> }; >> >> static unsigned long cpu_hw_rate, xo_rate; >> @@ -251,10 +258,84 @@ static void qcom_get_related_cpus(int index, struct cpumask *m) >> } >> } >> >> +static inline unsigned long qcom_lmh_vote_to_freq(u32 val) >> +{ >> + return (val & 0x3FF) * 19200; >> +} >> + >> +static void qcom_lmh_dcvs_notify(struct qcom_cpufreq_data *data) >> +{ >> + struct cpufreq_policy *policy = data->policy; >> + struct dev_pm_opp *opp; >> + struct device *dev; >> + unsigned long max_capacity, capacity, freq_hz, throttled_freq; >> + unsigned int val, freq; >> + >> + /* >> + * Get the h/w throttled frequency, normalize it using the >> + * registered opp table and use it to calculate thermal pressure. >> + */ >> + val = readl_relaxed(data->base + data->soc_data->reg_current_vote); > > I would find it cleaner to move the readl() into the helper function, as > you don't care about the register value, only the resulting frequency. Ok.. > >> + freq = qcom_lmh_vote_to_freq(val); >> + freq_hz = freq * HZ_PER_KHZ; >> + >> + dev = get_cpu_device(cpumask_first(policy->cpus)); >> + opp = dev_pm_opp_find_freq_floor(dev, &freq_hz); >> + if (IS_ERR(opp) && PTR_ERR(opp) == -ERANGE) >> + opp = dev_pm_opp_find_freq_ceil(dev, &freq_hz); >> + >> + throttled_freq = freq_hz / HZ_PER_KHZ; >> + >> + /* Update thermal pressure */ >> + >> + max_capacity = arch_scale_cpu_capacity(cpumask_first(policy->cpus)); >> + capacity = throttled_freq * max_capacity; >> + capacity /= policy->cpuinfo.max_freq; > > Perhaps, to avoid overflows if this is ever used on a 32-bit platform > use: > > mult_frac(max_capacity, throttled_freq, policy->cpuinfo.max_freq) yep. sounds good. > >> + >> + /* Don't pass boost capacity to scheduler */ >> + if (capacity > max_capacity) >> + capacity = max_capacity; >> + >> + arch_set_thermal_pressure(policy->cpus, max_capacity - capacity); >> + >> + /* >> + * If h/w throttled frequency is higher than what cpufreq has requested for, stop >> + * polling and switch back to interrupt mechanism >> + */ >> + >> + if (throttled_freq >= qcom_cpufreq_hw_get(cpumask_first(policy->cpus))) >> + /* Clear the existing interrupts and enable it back */ >> + enable_irq(data->lmh_dcvs_irq); >> + else >> + mod_delayed_work(system_highpri_wq, &data->lmh_dcvs_poll_work, >> + msecs_to_jiffies(10)); >> +} >> + >> +static void qcom_lmh_dcvs_poll(struct work_struct *work) >> +{ >> + struct qcom_cpufreq_data *data; >> + >> + data = container_of(work, struct qcom_cpufreq_data, lmh_dcvs_poll_work.work); >> + >> + qcom_lmh_dcvs_notify(data); >> +} >> + >> +static irqreturn_t qcom_lmh_dcvs_handle_irq(int irq, void *data) >> +{ >> + struct qcom_cpufreq_data *c_data = data; >> + >> + /* Disable interrupt and enable polling */ >> + disable_irq_nosync(c_data->lmh_dcvs_irq); >> + qcom_lmh_dcvs_notify(c_data); >> + >> + return 0; >> +} >> + >> static const struct qcom_cpufreq_soc_data qcom_soc_data = { >> .reg_enable = 0x0, >> .reg_freq_lut = 0x110, >> .reg_volt_lut = 0x114, >> + .reg_current_vote = 0x704, >> .reg_perf_state = 0x920, >> .lut_row_size = 32, >> }; >> @@ -274,6 +355,35 @@ static const struct of_device_id qcom_cpufreq_hw_match[] = { >> }; >> MODULE_DEVICE_TABLE(of, qcom_cpufreq_hw_match); >> >> +static int qcom_cpufreq_hw_lmh_init(struct cpufreq_policy *policy, int index) >> +{ >> + struct qcom_cpufreq_data *data = policy->driver_data; >> + struct platform_device *pdev = cpufreq_get_driver_data(); >> + struct device *cpu_dev = get_cpu_device(policy->cpu); >> + char irq_name[15]; >> + int ret; >> + >> + /* >> + * Look for LMh interrupt. If no interrupt line is specified / >> + * if there is an error, allow cpufreq to be enabled as usual. >> + */ >> + data->lmh_dcvs_irq = platform_get_irq(pdev, index); >> + if (data->lmh_dcvs_irq <= 0) >> + return data->lmh_dcvs_irq == -EPROBE_DEFER ? -EPROBE_DEFER : 0; >> + >> + snprintf(irq_name, sizeof(irq_name), "dcvsh-irq-%u", policy->cpu); >> + ret = devm_request_irq(cpu_dev, data->lmh_dcvs_irq, qcom_lmh_dcvs_handle_irq, >> + 0, irq_name, data); >> + if (ret) { >> + dev_err(&pdev->dev, "Error %d registering irq %x\n", ret, data->lmh_dcvs_irq); > > The irq number here won't have any meaning, and %x wouldn't be suitable. > > How about ..."Error registering %s: %d\n", irq_name, ret); ? ok. > >> + return 0; > > This sounds like a problem, wouldn't it be suitable to treat it as a > problem? I thought a lot about this. My point is even if LMh does not get enabled due to some reason, cpufreq should be enabled. If I return an error back from here, cpufreq will be disabled. > >> + } >> + data->policy = policy; > > Afaict, no one is going to access data->policy unless devm_request_irq() > succeeds and if it does and the interrupt fires immediately it would be > too late to set it here. So better move it earlier. > >> + INIT_DEFERRABLE_WORK(&data->lmh_dcvs_poll_work, qcom_lmh_dcvs_poll); > > What if the interrupt fires before you initialize the work? Better move > this higher up. I will move this and the data->policy = policy above before requesting the interrupt. > >> + >> + return 0; >> +} >> + >> static int qcom_cpufreq_hw_cpu_init(struct cpufreq_policy *policy) >> { >> struct platform_device *pdev = cpufreq_get_driver_data(); >> @@ -370,6 +480,10 @@ static int qcom_cpufreq_hw_cpu_init(struct cpufreq_policy *policy) >> dev_warn(cpu_dev, "failed to enable boost: %d\n", ret); >> } >> >> + ret = qcom_cpufreq_hw_lmh_init(policy, index); >> + if (ret) >> + goto error; >> + >> return 0; >> error: >> kfree(data); >> @@ -389,6 +503,10 @@ static int qcom_cpufreq_hw_cpu_exit(struct cpufreq_policy *policy) >> >> dev_pm_opp_remove_all_dynamic(cpu_dev); >> dev_pm_opp_of_cpumask_remove_table(policy->related_cpus); >> + if (data->lmh_dcvs_irq > 0) { >> + devm_free_irq(cpu_dev, data->lmh_dcvs_irq, data); > > As init/exit are called multiple times you should avoid the devm > variants. Yes. I think Viresh was also mentioning this. I will move to non devm version. > > Regards, > Bjorn > >> + cancel_delayed_work_sync(&data->lmh_dcvs_poll_work); >> + } >> kfree(policy->freq_table); >> kfree(data); >> iounmap(base); >> -- >> 2.25.1 >>
On 7/12/21 12:41 AM, Viresh Kumar wrote: > On 09-07-21, 11:37, Thara Gopinath wrote: >> On 7/9/21 2:46 AM, Viresh Kumar wrote: >>>> @@ -389,6 +503,10 @@ static int qcom_cpufreq_hw_cpu_exit(struct cpufreq_policy *policy) >>>> dev_pm_opp_remove_all_dynamic(cpu_dev); >>>> dev_pm_opp_of_cpumask_remove_table(policy->related_cpus); >>>> + if (data->lmh_dcvs_irq > 0) { >>>> + devm_free_irq(cpu_dev, data->lmh_dcvs_irq, data); >>> >>> Why using devm variants here and while requesting the irq ? > > Missed this one ? Yep. I just replied to Bjorn's email on this. I will move to non devm version. > >>> >>>> + cancel_delayed_work_sync(&data->lmh_dcvs_poll_work); >>>> + } >>> >>> Please move this to qcom_cpufreq_hw_lmh_exit() or something. >> >> Ok. >> >>> >>> Now with sequence of disabling interrupt, etc, I see a potential >>> problem. >>> >>> CPU0 CPU1 >>> >>> qcom_cpufreq_hw_cpu_exit() >>> -> devm_free_irq(); >>> qcom_lmh_dcvs_poll() >>> -> qcom_lmh_dcvs_notify() >>> -> enable_irq() >>> >>> -> cancel_delayed_work_sync(); >>> >>> >>> What will happen if enable_irq() gets called after freeing the irq ? >>> Not sure, but it looks like you will hit this then from manage.c: >>> >>> WARN(!desc->irq_data.chip, KERN_ERR "enable_irq before >>> setup/request_irq: irq %u\n", irq)) >>> >>> ? >>> >>> You got a chicken n egg problem :) >> >> Yes indeed! But also it is a very rare chicken and egg problem. >> The scenario here is that the cpus are busy and running load causing a >> thermal overrun and lmh is engaged. At the same time for this issue to be >> hit the cpu is trying to exit/disable cpufreq. > > Yes, it is a very specific case but it needs to be resolved anyway. You don't > want to get this ever :) > >> Calling >> cancel_delayed_work_sync first could solve this issue, right ? >> cancel_delayed_work_sync guarantees the work not to be pending even if >> it requeues itself on return. So once the delayed work is cancelled, the >> interrupts can be safely disabled. Thoughts ? > > I don't think even that would provide such guarantees to you here, as there is > a chance the work gets queued again because of an interrupt that triggers right > after you cancel the work. > > The basic way of solving such issues is that once you cancel something, you need > to guarantee that it doesn't get triggered again, no matter what. > > The problem here I see is with your design itself, both delayed work and irq can > enable each other, so no matter which one you disable first, won't be > sufficient. You need to fix that design somehow. So I really need the interrupt to fire and then the timer to kick in and take up the monitoring. I can think of introducing a variable is_disabled which is updated and read under a spinlock. qcom_cpufreq_hw_cpu_exit can hold the spinlock and set is_disabled to true prior to cancelling the work queue or disabling the interrupt. Before re-enabling the interrupt or re-queuing the work in qcom_lmh_dcvs_notify, is_disabled can be read and checked. But does this problem not exist in target_index , fast_switch etc also ? One cpu can be disabling and the other one can be updating the target right? >
On 12-07-21, 21:18, Thara Gopinath wrote: > So I really need the interrupt to fire and then the timer to kick in and > take up the monitoring. I can think of introducing a variable is_disabled > which is updated and read under a spinlock. qcom_cpufreq_hw_cpu_exit can > hold the spinlock and set is_disabled to true prior to cancelling the work > queue or disabling the interrupt. Before re-enabling the interrupt or > re-queuing the work in qcom_lmh_dcvs_notify, is_disabled can be read and > checked. Or you can make the lmh_dcvs_poll_work item a pointer and mark it NULL in exit, with proper locking etc. > But does this problem not exist in target_index , fast_switch etc also ? One > cpu can be disabling and the other one can be updating the target right? The race doesn't happen there as cpufreq_unregister_driver() takes care of stopping everything before removing the policy. To be more precise, governor's ->stop() function is responsible for making sure that frequency won't be updated any further.
On 7/12/21 11:18 PM, Viresh Kumar wrote: > On 12-07-21, 21:18, Thara Gopinath wrote: >> So I really need the interrupt to fire and then the timer to kick in and >> take up the monitoring. I can think of introducing a variable is_disabled >> which is updated and read under a spinlock. qcom_cpufreq_hw_cpu_exit can >> hold the spinlock and set is_disabled to true prior to cancelling the work >> queue or disabling the interrupt. Before re-enabling the interrupt or >> re-queuing the work in qcom_lmh_dcvs_notify, is_disabled can be read and >> checked. > > Or you can make the lmh_dcvs_poll_work item a pointer and mark it NULL in exit, > with proper locking etc. Yes it could work. I will spin the next version with either this or introducing a new variable with locking. > >> But does this problem not exist in target_index , fast_switch etc also ? One >> cpu can be disabling and the other one can be updating the target right? > > The race doesn't happen there as cpufreq_unregister_driver() takes care of > stopping everything before removing the policy. To be more precise, governor's > ->stop() function is responsible for making sure that frequency won't be updated > any further. >
diff --git a/drivers/cpufreq/qcom-cpufreq-hw.c b/drivers/cpufreq/qcom-cpufreq-hw.c index f86859bf76f1..bb5fc700d913 100644 --- a/drivers/cpufreq/qcom-cpufreq-hw.c +++ b/drivers/cpufreq/qcom-cpufreq-hw.c @@ -7,6 +7,7 @@ #include <linux/cpufreq.h> #include <linux/init.h> #include <linux/interconnect.h> +#include <linux/interrupt.h> #include <linux/kernel.h> #include <linux/module.h> #include <linux/of_address.h> @@ -22,10 +23,13 @@ #define CLK_HW_DIV 2 #define LUT_TURBO_IND 1 +#define HZ_PER_KHZ 1000 + struct qcom_cpufreq_soc_data { u32 reg_enable; u32 reg_freq_lut; u32 reg_volt_lut; + u32 reg_current_vote; u32 reg_perf_state; u8 lut_row_size; }; @@ -33,7 +37,10 @@ struct qcom_cpufreq_soc_data { struct qcom_cpufreq_data { void __iomem *base; struct resource *res; + struct delayed_work lmh_dcvs_poll_work; const struct qcom_cpufreq_soc_data *soc_data; + struct cpufreq_policy *policy; + int lmh_dcvs_irq; }; static unsigned long cpu_hw_rate, xo_rate; @@ -251,10 +258,84 @@ static void qcom_get_related_cpus(int index, struct cpumask *m) } } +static inline unsigned long qcom_lmh_vote_to_freq(u32 val) +{ + return (val & 0x3FF) * 19200; +} + +static void qcom_lmh_dcvs_notify(struct qcom_cpufreq_data *data) +{ + struct cpufreq_policy *policy = data->policy; + struct dev_pm_opp *opp; + struct device *dev; + unsigned long max_capacity, capacity, freq_hz, throttled_freq; + unsigned int val, freq; + + /* + * Get the h/w throttled frequency, normalize it using the + * registered opp table and use it to calculate thermal pressure. + */ + val = readl_relaxed(data->base + data->soc_data->reg_current_vote); + freq = qcom_lmh_vote_to_freq(val); + freq_hz = freq * HZ_PER_KHZ; + + dev = get_cpu_device(cpumask_first(policy->cpus)); + opp = dev_pm_opp_find_freq_floor(dev, &freq_hz); + if (IS_ERR(opp) && PTR_ERR(opp) == -ERANGE) + opp = dev_pm_opp_find_freq_ceil(dev, &freq_hz); + + throttled_freq = freq_hz / HZ_PER_KHZ; + + /* Update thermal pressure */ + + max_capacity = arch_scale_cpu_capacity(cpumask_first(policy->cpus)); + capacity = throttled_freq * max_capacity; + capacity /= policy->cpuinfo.max_freq; + + /* Don't pass boost capacity to scheduler */ + if (capacity > max_capacity) + capacity = max_capacity; + + arch_set_thermal_pressure(policy->cpus, max_capacity - capacity); + + /* + * If h/w throttled frequency is higher than what cpufreq has requested for, stop + * polling and switch back to interrupt mechanism + */ + + if (throttled_freq >= qcom_cpufreq_hw_get(cpumask_first(policy->cpus))) + /* Clear the existing interrupts and enable it back */ + enable_irq(data->lmh_dcvs_irq); + else + mod_delayed_work(system_highpri_wq, &data->lmh_dcvs_poll_work, + msecs_to_jiffies(10)); +} + +static void qcom_lmh_dcvs_poll(struct work_struct *work) +{ + struct qcom_cpufreq_data *data; + + data = container_of(work, struct qcom_cpufreq_data, lmh_dcvs_poll_work.work); + + qcom_lmh_dcvs_notify(data); +} + +static irqreturn_t qcom_lmh_dcvs_handle_irq(int irq, void *data) +{ + struct qcom_cpufreq_data *c_data = data; + + /* Disable interrupt and enable polling */ + disable_irq_nosync(c_data->lmh_dcvs_irq); + qcom_lmh_dcvs_notify(c_data); + + return 0; +} + static const struct qcom_cpufreq_soc_data qcom_soc_data = { .reg_enable = 0x0, .reg_freq_lut = 0x110, .reg_volt_lut = 0x114, + .reg_current_vote = 0x704, .reg_perf_state = 0x920, .lut_row_size = 32, }; @@ -274,6 +355,35 @@ static const struct of_device_id qcom_cpufreq_hw_match[] = { }; MODULE_DEVICE_TABLE(of, qcom_cpufreq_hw_match); +static int qcom_cpufreq_hw_lmh_init(struct cpufreq_policy *policy, int index) +{ + struct qcom_cpufreq_data *data = policy->driver_data; + struct platform_device *pdev = cpufreq_get_driver_data(); + struct device *cpu_dev = get_cpu_device(policy->cpu); + char irq_name[15]; + int ret; + + /* + * Look for LMh interrupt. If no interrupt line is specified / + * if there is an error, allow cpufreq to be enabled as usual. + */ + data->lmh_dcvs_irq = platform_get_irq(pdev, index); + if (data->lmh_dcvs_irq <= 0) + return data->lmh_dcvs_irq == -EPROBE_DEFER ? -EPROBE_DEFER : 0; + + snprintf(irq_name, sizeof(irq_name), "dcvsh-irq-%u", policy->cpu); + ret = devm_request_irq(cpu_dev, data->lmh_dcvs_irq, qcom_lmh_dcvs_handle_irq, + 0, irq_name, data); + if (ret) { + dev_err(&pdev->dev, "Error %d registering irq %x\n", ret, data->lmh_dcvs_irq); + return 0; + } + data->policy = policy; + INIT_DEFERRABLE_WORK(&data->lmh_dcvs_poll_work, qcom_lmh_dcvs_poll); + + return 0; +} + static int qcom_cpufreq_hw_cpu_init(struct cpufreq_policy *policy) { struct platform_device *pdev = cpufreq_get_driver_data(); @@ -370,6 +480,10 @@ static int qcom_cpufreq_hw_cpu_init(struct cpufreq_policy *policy) dev_warn(cpu_dev, "failed to enable boost: %d\n", ret); } + ret = qcom_cpufreq_hw_lmh_init(policy, index); + if (ret) + goto error; + return 0; error: kfree(data); @@ -389,6 +503,10 @@ static int qcom_cpufreq_hw_cpu_exit(struct cpufreq_policy *policy) dev_pm_opp_remove_all_dynamic(cpu_dev); dev_pm_opp_of_cpumask_remove_table(policy->related_cpus); + if (data->lmh_dcvs_irq > 0) { + devm_free_irq(cpu_dev, data->lmh_dcvs_irq, data); + cancel_delayed_work_sync(&data->lmh_dcvs_poll_work); + } kfree(policy->freq_table); kfree(data); iounmap(base);
Add interrupt support to notify the kernel of h/w initiated frequency throttling by LMh. Convey this to scheduler via thermal presssure interface. Signed-off-by: Thara Gopinath <thara.gopinath@linaro.org> --- v2->v3: - Cosmetic fixes from review comments on the list. - Moved all LMh initializations to qcom_cpufreq_hw_lmh_init. - Added freeing of LMh interrupt and cancelling the polling worker to qcom_cpufreq_hw_cpu_exit as per Viresh's suggestion. - LMh interrupts are now tied to cpu dev and not cpufreq dev. This will be useful for further generation of SoCs where the same interrupt signals multiple cpu clusters. v1->v2: - Introduced qcom_cpufreq_hw_lmh_init to consolidate LMh related initializations as per Viresh's review comment. - Moved the piece of code restarting polling/re-enabling LMh interrupt to qcom_lmh_dcvs_notify therby simplifying isr and timer callback as per Viresh's suggestion. - Droped cpus from qcom_cpufreq_data and instead using cpus from cpufreq_policy in qcom_lmh_dcvs_notify as per Viresh's review comment. - Dropped dt property qcom,support-lmh as per Bjorn's suggestion. - Other minor/cosmetic fixes drivers/cpufreq/qcom-cpufreq-hw.c | 118 ++++++++++++++++++++++++++++++ 1 file changed, 118 insertions(+) -- 2.25.1