On Thu, Oct 10, 2019 at 01:39:34PM +0200, Ulf Hansson wrote:
> Introduce a PSCI DT helper function, psci_dt_attach_cpu(), which takes a
> CPU number as an in-parameter and tries to attach the CPU's struct device
> to its corresponding PM domain.
>
> Let's makes use of dev_pm_domain_attach_by_name(), as it allows us to
> specify "psci" as the "name" of the PM domain to attach to. Additionally,
> let's also prepare the attached device to be power managed via runtime PM.
>
> Signed-off-by: Ulf Hansson <ulf.hansson@xxxxxxxxxx>
> ---
> drivers/cpuidle/cpuidle-psci-domain.c | 21 +++++++++++++++++++++
> drivers/cpuidle/cpuidle-psci.h | 6 ++++++
> 2 files changed, 27 insertions(+)
>
> diff --git a/drivers/cpuidle/cpuidle-psci-domain.c b/drivers/cpuidle/cpuidle-psci-domain.c
> index 3f5143ccc3e0..7429fd7626a1 100644
> --- a/drivers/cpuidle/cpuidle-psci-domain.c
> +++ b/drivers/cpuidle/cpuidle-psci-domain.c
> @@ -9,9 +9,11 @@
>
> #define pr_fmt(fmt) "CPUidle PSCI: " fmt
>
> +#include <linux/cpu.h>
> #include <linux/device.h>
> #include <linux/kernel.h>
> #include <linux/pm_domain.h>
> +#include <linux/pm_runtime.h>
> #include <linux/psci.h>
> #include <linux/slab.h>
> #include <linux/string.h>
> @@ -279,3 +281,22 @@ static int __init psci_idle_init_domains(void)
> return ret;
> }
> subsys_initcall(psci_idle_init_domains);
> +
> +struct device *psci_dt_attach_cpu(int cpu)
> +{
> + struct device *dev;
> +
> + /* Currently limit the hierarchical topology to be used in OSI mode. */
> + if (!psci_has_osi_support())
> + return NULL;
> +
> + dev = dev_pm_domain_attach_by_name(get_cpu_device(cpu), "psci");
This clarifies the need for the fixed name. But why not just go by index 0
as the consumer of these psci power-domains will have only one power domain
entry. Why do we need this name compulsory ? Further, it's specified as
optional in the generic binding, do we make it "required" for this psci
idle states binding anywhere that I missed ?
--
Regards,
Sudeep
