linux-kernel - Re: [PATCH v4 3/5] drivers: psci: refactor psci_cpu_init

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Message-ID: <20160609132408.GA16831@red-moon>
Date:	Thu, 9 Jun 2016 14:24:08 +0100
From:	Lorenzo Pieralisi <lorenzo.pieralisi@....com>
To:	Sudeep Holla <sudeep.holla@....com>
Cc:	"Rafael J. Wysocki" <rjw@...ysocki.net>,
	linux-acpi@...r.kernel.org, linux-kernel@...r.kernel.org,
	linux-arm-kernel@...ts.infradead.org,
	Al Stone <al.stone@...aro.org>,
	Prashanth Prakash <pprakash@...eaurora.org>,
	Ashwin Chaugule <ashwin.chaugule@...aro.org>,
	Mark Rutland <mark.rutland@....com>
Subject: Re: [PATCH v4 3/5] drivers: psci: refactor psci_cpu_init_idle in
 preparation for ACPI LPI support

On Tue, Apr 19, 2016 at 01:30:11PM +0100, Sudeep Holla wrote:
> Inorder to accomodate bot DT and ACPI LPI support in psci_cpu_init_idle,
> move the device tree specific into psci_dt_cpu_init_idle.
> 
> Cc: Mark Rutland <mark.rutland@....com>
> Cc: Lorenzo Pieralisi <lorenzo.pieralisi@....com>
> Cc: linux-arm-kernel@...ts.infradead.org
> Signed-off-by: Sudeep Holla <sudeep.holla@....com>
> ---
>  drivers/firmware/psci.c | 23 +++++++++--------------
>  1 file changed, 9 insertions(+), 14 deletions(-)
> 
> diff --git a/drivers/firmware/psci.c b/drivers/firmware/psci.c
> index 11bfee8b79a9..af6c5c839568 100644
> --- a/drivers/firmware/psci.c
> +++ b/drivers/firmware/psci.c
> @@ -250,11 +250,11 @@ static int __init psci_features(u32 psci_func_id)
>  #ifdef CONFIG_CPU_IDLE
>  static DEFINE_PER_CPU_READ_MOSTLY(u32 *, psci_power_state);
>  
> -static int psci_dt_cpu_init_idle(struct device_node *cpu_node, int cpu)
> +static int psci_dt_cpu_init_idle(unsigned int cpu)

Unfortunately you would break ARM 32-bit if you did that.

>  {
>  	int i, ret, count = 0;
>  	u32 *psci_states;
> -	struct device_node *state_node;
> +	struct device_node *state_node, *cpu_node;
>  
>  	/*
>  	 * If the PSCI cpu_suspend function hook has not been initialized
> @@ -263,6 +263,10 @@ static int psci_dt_cpu_init_idle(struct device_node *cpu_node, int cpu)
>  	if (!psci_ops.cpu_suspend)
>  		return -EOPNOTSUPP;
>  
> +	cpu_node = of_get_cpu_node(cpu, NULL);
> +	if (!cpu_node)
> +		return -ENODEV;
> +
>  	/* Count idle states */
>  	while ((state_node = of_parse_phandle(cpu_node, "cpu-idle-states",
>  					      count))) {
> @@ -303,27 +307,18 @@ static int psci_dt_cpu_init_idle(struct device_node *cpu_node, int cpu)
>  	}
>  	/* Idle states parsed correctly, initialize per-cpu pointer */
>  	per_cpu(psci_power_state, cpu) = psci_states;
> +	of_node_put(cpu_node);
>  	return 0;
>  
>  free_mem:
> +	of_node_put(cpu_node);
>  	kfree(psci_states);
>  	return ret;
>  }
>  
>  int psci_cpu_init_idle(unsigned int cpu)
>  {
> -	struct device_node *cpu_node;
> -	int ret;
> -
> -	cpu_node = of_get_cpu_node(cpu, NULL);
> -	if (!cpu_node)
> -		return -ENODEV;
> -
> -	ret = psci_dt_cpu_init_idle(cpu_node, cpu);
> -
> -	of_node_put(cpu_node);
> -
> -	return ret;
> +	return psci_dt_cpu_init_idle(cpu);

How about leaving code as is and you wrap the cpu_node retrieval:

if (!acpi_disabled) {
	acpi_idle_init();
} else {
	cpu_node = of_get_cpu_node(cpu, NULL);
	if (!cpu_node)
		return -ENODEV;

	ret = psci_dt_cpu_init_idle(cpu_node, cpu);

	of_node_put(cpu_node);
}

?

Alternatively, you could create an intermediate stub
__psci_dt_cpu_init_idle(), that will be used for CONFIG_ARM
cpuidle_ops.init and psci_dt_cpu_init_idle() after retrieving
the cpu_node, which I think is slightly cleaner.

Lorenzo