Re: [PATCH v5 1/2] PM / Domains: Add support for 'required-opps' to set default perf state
From: Ulf Hansson <hidden>
Date: 2021-08-02 13:00:10
Also in:
linux-arm-msm, linux-pm, lkml
On Tue, 20 Jul 2021 at 09:12, Rajendra Nayak [off-list ref] wrote:
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Some devices within power domains with performance states do not support DVFS, but still need to vote on a default/static state while they are active. They can express this using the 'required-opps' property in device tree, which points to the phandle of the OPP supported by the corresponding power-domains. Add support to parse this information from DT and then set the specified performance state during attach and drop it on detach. runtime suspend/resume callbacks already have logic to drop/set the vote as needed and should take care of dropping the default perf state vote on runtime suspend and restore it back on runtime resume. Signed-off-by: Rajendra Nayak <redacted> --- drivers/base/power/domain.c | 28 +++++++++++++++++++++++++--- include/linux/pm_domain.h | 1 + 2 files changed, 26 insertions(+), 3 deletions(-)diff --git a/drivers/base/power/domain.c b/drivers/base/power/domain.c index a934c67..f454031 100644 --- a/drivers/base/power/domain.c +++ b/drivers/base/power/domain.c@@ -2598,6 +2598,12 @@ static void genpd_dev_pm_detach(struct device *dev, bool power_off) dev_dbg(dev, "removing from PM domain %s\n", pd->name); + /* Drop the default performance state */ + if (dev_gpd_data(dev)->default_pstate) { + dev_pm_genpd_set_performance_state(dev, 0); + dev_gpd_data(dev)->default_pstate = 0; + } + for (i = 1; i < GENPD_RETRY_MAX_MS; i <<= 1) { ret = genpd_remove_device(pd, dev); if (ret != -EAGAIN)@@ -2635,9 +2641,10 @@ static void genpd_dev_pm_sync(struct device *dev) static int __genpd_dev_pm_attach(struct device *dev, struct device *base_dev, unsigned int index, bool power_on) { + struct device_node *np; struct of_phandle_args pd_args; struct generic_pm_domain *pd; - int ret; + int ret, pstate; ret = of_parse_phandle_with_args(dev->of_node, "power-domains", "#power-domain-cells", index, &pd_args);@@ -2675,10 +2682,25 @@ static int __genpd_dev_pm_attach(struct device *dev, struct device *base_dev, genpd_unlock(pd); } - if (ret) + if (ret) { genpd_remove_device(pd, dev); + return -EPROBE_DEFER; + } + + /* Set the default performance state */ + np = base_dev->of_node;
Please use dev->of_node instead (it is set to the same of_node as base_dev by the callers of __genpd_dev_pm_attach) as it's more consistent with existing code.
+ if (of_parse_phandle(np, "required-opps", index)) {
+ pstate = of_get_required_opp_performance_state(np, index);
+ if (pstate < 0) {
+ ret = pstate;
+ dev_err(dev, "failed to set required performance state for power-domain %s: %d\n",
+ pd->name, ret);
+ }
+ dev_pm_genpd_set_performance_state(dev, pstate);
+ dev_gpd_data(dev)->default_pstate = pstate;This doesn't look entirely correct to me. If we fail to translate a required opp to a performance state, we shouldn't try to set it. Perhaps it's also easier to call of_get_required_opp_performance_state() unconditionally of whether a "required-opps" specifier exists. If it fails with the translation, then we just skip setting a default state and continue with returning 1. Would that work?
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+ } - return ret ? -EPROBE_DEFER : 1; + return ret ? ret : 1; } /**diff --git a/include/linux/pm_domain.h b/include/linux/pm_domain.h index 21a0577..67017c9 100644 --- a/include/linux/pm_domain.h +++ b/include/linux/pm_domain.h@@ -198,6 +198,7 @@ struct generic_pm_domain_data { struct notifier_block *power_nb; int cpu; unsigned int performance_state; + unsigned int default_pstate; unsigned int rpm_pstate; ktime_t next_wakeup; void *data; --QUALCOMM INDIA, on behalf of Qualcomm Innovation Center, Inc. is a member of Code Aurora Forum, hosted by The Linux Foundation
Kind regards Uffe