[PATCH 3/8] PM / Domains: Allow domain power states to be read from DT
Ulf Hansson
ulf.hansson at linaro.org
Thu Oct 6 02:47:03 PDT 2016
On 5 October 2016 at 22:31, Lina Iyer <lina.iyer at linaro.org> wrote:
> This patch allows domains to define idle states in the DT. SoC's can
> define domain idle states in DT using the "domain-idle-states" property
> of the domain provider. Calling of_pm_genpd_init() will read the idle
> states and initialize the genpd for the domain.
>
> In addition to the entry and exit latency for idle state, also add
> residency_ns, param and of_node property to each state. A domain idling
> in a state is only power effecient if it stays idle for a certain period
> in that state. The residency provides this minimum time for the idle
> state to provide power benefits. The param is a state specific u32 value
> that the platform may use for that idle state.
>
> This patch is based on the original patch by Marc Titinger.
>
> Signed-off-by: Marc Titinger <mtitinger+renesas at baylibre.com>
> Signed-off-by: Ulf Hansson <ulf.hansson at linaro.org>
> Signed-off-by: Lina Iyer <lina.iyer at linaro.org>
> ---
> drivers/base/power/domain.c | 103 ++++++++++++++++++++++++++++++++++++++++++++
> include/linux/pm_domain.h | 8 ++++
> 2 files changed, 111 insertions(+)
>
> diff --git a/drivers/base/power/domain.c b/drivers/base/power/domain.c
> index 740afa9..368a5b8 100644
> --- a/drivers/base/power/domain.c
> +++ b/drivers/base/power/domain.c
> @@ -1895,6 +1895,109 @@ out:
> return ret ? -EPROBE_DEFER : 0;
> }
> EXPORT_SYMBOL_GPL(genpd_dev_pm_attach);
> +
> +static const struct of_device_id idle_state_match[] = {
> + { .compatible = "arm,idle-state", },
> + { }
> +};
> +
> +static int read_genpd_state(struct genpd_power_state *genpd_state,
/s/read_genpd_state/genpd_parse_state
> + struct device_node *state_node)
> +{
> + int err = 0;
No need to assign err to 0.
> + u32 latency;
> + u32 residency;
> + u32 entry_latency, exit_latency;
> + const struct of_device_id *match_id;
> +
> + match_id = of_match_node(idle_state_match, state_node);
> + if (!match_id)
> + return -EINVAL;
> +
> + err = of_property_read_u32(state_node, "entry-latency-us",
> + &entry_latency);
> + if (err) {
> + pr_debug(" * %s missing entry-latency-us property\n",
> + state_node->full_name);
> + return -EINVAL;
> + }
> +
> + err = of_property_read_u32(state_node, "exit-latency-us",
> + &exit_latency);
> + if (err) {
> + pr_debug(" * %s missing exit-latency-us property\n",
> + state_node->full_name);
> + return -EINVAL;
> + }
> +
> + err = of_property_read_u32(state_node, "min-residency-us", &residency);
> + if (!err)
> + genpd_state->residency_ns = 1000 * residency;
> +
> + latency = entry_latency + exit_latency;
Hmm, this is probably not what you want.
The genpd governor, via __default_power_down_ok(), already adds the
->power_on_latency_ns and the ->power_off_latency_ns, when it
validates which idle state you are allowed to enter.
> + genpd_state->power_on_latency_ns = 1000 * latency;
> + genpd_state->power_off_latency_ns = 1000 * entry_latency;
> +
> + return 0;
> +}
> +
> +/**
> + * of_genpd_parse_idle_states: Return array of idle states for the genpd.
> + *
> + * @dn: The genpd device node
> + * @states: The pointer to which the state array will be saved.
> + * @n: The count of elements in the array returned from this function.
> + *
> + * Returns the device states parsed from the OF node. The memory for the states
> + * is allocated by this function and is the responsibility of the caller to
> + * free the memory after use.
> + */
> +int of_genpd_parse_idle_states(struct device_node *dn,
> + struct genpd_power_state **states, int *n)
> +{
> + struct genpd_power_state *st;
> + struct device_node *np;
> + int i, ret = 0;
> + int count;
> +
> + for (count = 0; ; count++)
> + if (!of_parse_phandle(dn, "domain-idle-states", count))
> + break;
I think it's better to use of_count_phandle_with_args() to find out
the number of phandles.
> +
> + st = kcalloc(count, sizeof(*st), GFP_KERNEL);
> + if (!st)
> + return -ENOMEM;
> +
> + for (i = 0; i < count; i++) {
> + np = of_parse_phandle(dn, "domain-idle-states", i);
Isn't this a case of when it would be convenient to use the
of_phandle_iterator*() APIs?
> + if (!np) {
> + ret = -EFAULT;
> + break;
> + }
> +
> + ret = read_genpd_state(&st[i], np);
> + if (ret) {
> + pr_err
> + ("Parsing idle state node %s failed with err %d\n",
> + np->full_name, ret);
> + of_node_put(np);
> + break;
> + }
> + of_node_put(np);
> + }
> +
> + if (ret) {
> + kfree(st);
> + return ret;
> + }
> +
> + *n = count;
> + *states = st;
> +
> + return 0;
> +}
> +EXPORT_SYMBOL(of_genpd_parse_idle_states);
> +
> #endif /* CONFIG_PM_GENERIC_DOMAINS_OF */
>
>
> diff --git a/include/linux/pm_domain.h b/include/linux/pm_domain.h
> index c113713..4c9152d 100644
> --- a/include/linux/pm_domain.h
> +++ b/include/linux/pm_domain.h
> @@ -204,6 +204,8 @@ extern int of_genpd_add_device(struct of_phandle_args *args,
> extern int of_genpd_add_subdomain(struct of_phandle_args *parent,
> struct of_phandle_args *new_subdomain);
> extern struct generic_pm_domain *of_genpd_remove_last(struct device_node *np);
> +extern int of_genpd_parse_idle_states(struct device_node *dn,
> + struct genpd_power_state **states, int *n);
>
> int genpd_dev_pm_attach(struct device *dev);
> #else /* !CONFIG_PM_GENERIC_DOMAINS_OF */
> @@ -233,6 +235,12 @@ static inline int of_genpd_add_subdomain(struct of_phandle_args *parent,
> return -ENODEV;
> }
>
> +static inline int of_genpd_parse_idle_states(struct device_node *dn,
> + struct genpd_power_state **states, int *n)
> +{
> + return -ENODEV;
> +}
> +
> static inline int genpd_dev_pm_attach(struct device *dev)
> {
> return -ENODEV;
> --
> 2.7.4
>
Kind regards
Uffe
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