Quoting Rajendra Nayak (2021-07-16 03:00:57)
> Some devics within power domains with performance states do not
devices
> 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.
> Also drop/set as part of runtime suspend/resume callbacks.
>
> Signed-off-by: Rajendra Nayak <rnayak@xxxxxxxxxxxxxx>
> ---
> drivers/base/power/domain.c | 37 ++++++++++++++++++++++++++++++++++---
> include/linux/pm_domain.h | 1 +
> 2 files changed, 35 insertions(+), 3 deletions(-)
>
> diff --git a/drivers/base/power/domain.c b/drivers/base/power/domain.c
> index a934c67..dcc0b71 100644
> --- a/drivers/base/power/domain.c
> +++ b/drivers/base/power/domain.c
> @@ -1000,6 +1008,8 @@ static int genpd_runtime_resume(struct device *dev)
> genpd_stop_dev(genpd, dev);
> err_poweroff:
> if (!pm_runtime_is_irq_safe(dev) || genpd_is_irq_safe(genpd)) {
> + if (default_pstate)
> + dev_pm_genpd_set_performance_state(dev, 0);
> genpd_lock(genpd);
> gpd_data->rpm_pstate = genpd_drop_performance_state(dev);
Maybe this should be
prev_state = genpd_drop_performance_state(dev);
if (!default_pstate)
gdp_data->rpm_pstate = prev_state;
so we don't call dev_pm_genpd_set_performance_state() effectively twice?
Also it would make sure we call dev_pm_genpd_set_performance_state()
underneath the genpd_lock() if that is important. Similarly do that on
suspend path.
> genpd_power_off(genpd, true, 0);
> @@ -2598,6 +2608,12 @@ 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)
> @@ -2675,10 +2692,24 @@ 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;
> + if (of_parse_phandle(np, "required-opps", index)) {
> + pstate = of_get_required_opp_performance_state(np, index);
> + if (pstate < 0) {
> + dev_err(dev, "failed to set pstate:%d", pstate);
Missing newline on printk. Also can we spell out pstate as "failed to
set required performance state %d for power-domain %d"?
> + ret = pstate;
> + }
> + dev_pm_genpd_set_performance_state(dev, pstate);
> + dev_gpd_data(dev)->default_pstate = pstate;
> + }
>
> - return ret ? -EPROBE_DEFER : 1;
> + return ret ? ret : 1;
> }
>
> /**
