linux-kernel - Re: [PATCH 05/18] drivers: firmware: psci: Simplify state node parsing

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Message-ID: <20190607150144.GD15577@e107155-lin>
Date:   Fri, 7 Jun 2019 16:01:44 +0100
From:   Sudeep Holla <sudeep.holla@....com>
To:     Ulf Hansson <ulf.hansson@...aro.org>
Cc:     Lorenzo Pieralisi <Lorenzo.Pieralisi@....com>,
        Mark Rutland <mark.rutland@....com>,
        linux-arm-kernel@...ts.infradead.org,
        "Rafael J . Wysocki" <rjw@...ysocki.net>,
        Daniel Lezcano <daniel.lezcano@...aro.org>,
        "Raju P . L . S . S . S . N" <rplsssn@...eaurora.org>,
        Amit Kucheria <amit.kucheria@...aro.org>,
        Bjorn Andersson <bjorn.andersson@...aro.org>,
        Stephen Boyd <sboyd@...nel.org>,
        Niklas Cassel <niklas.cassel@...aro.org>,
        Tony Lindgren <tony@...mide.com>,
        Kevin Hilman <khilman@...nel.org>,
        Lina Iyer <ilina@...eaurora.org>,
        Viresh Kumar <viresh.kumar@...aro.org>,
        Vincent Guittot <vincent.guittot@...aro.org>,
        Geert Uytterhoeven <geert+renesas@...der.be>,
        Souvik Chakravarty <souvik.chakravarty@....com>,
        Sudeep Holla <sudeep.holla@....com>, linux-pm@...r.kernel.org,
        linux-arm-msm@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH 05/18] drivers: firmware: psci: Simplify state node
 parsing

On Mon, May 13, 2019 at 09:22:47PM +0200, Ulf Hansson wrote:
> Instead of iterating through all the state nodes in DT, to find out how
> many states that needs to be allocated, let's use the number already known
> by the cpuidle driver. In this way we can drop the iteration altogether.
> 
> Signed-off-by: Ulf Hansson <ulf.hansson@...aro.org>
> Acked-by: Daniel Lezcano <daniel.lezcano@...aro.org>
> ---
> 
> Changes:
> 	- None.
> 
> ---
>  drivers/firmware/psci/psci.c | 25 ++++++++++++-------------
>  1 file changed, 12 insertions(+), 13 deletions(-)
> 
> diff --git a/drivers/firmware/psci/psci.c b/drivers/firmware/psci/psci.c
> index 88e90e0f06b9..9c2180bcee4c 100644
> --- a/drivers/firmware/psci/psci.c
> +++ b/drivers/firmware/psci/psci.c
> @@ -306,26 +306,20 @@ static int psci_dt_parse_state_node(struct device_node *np, u32 *state)
>  static int psci_dt_cpu_init_idle(struct cpuidle_driver *drv,
>  			struct device_node *cpu_node, int cpu)
>  {
> -	int i, ret = 0, count = 0;
> +	int i, ret = 0, num_state_nodes = drv->state_count - 1;
>  	u32 *psci_states;
>  	struct device_node *state_node;
>  
> -	/* Count idle states */
> -	while ((state_node = of_parse_phandle(cpu_node, "cpu-idle-states",
> -					      count))) {
> -		count++;
> -		of_node_put(state_node);
> -	}
> -
> -	if (!count)
> -		return -ENODEV;
> -
> -	psci_states = kcalloc(count, sizeof(*psci_states), GFP_KERNEL);
> +	psci_states = kcalloc(num_state_nodes, sizeof(*psci_states),
> +			GFP_KERNEL);
>  	if (!psci_states)
>  		return -ENOMEM;
>  
> -	for (i = 0; i < count; i++) {
> +	for (i = 0; i < num_state_nodes; i++) {
>  		state_node = of_parse_phandle(cpu_node, "cpu-idle-states", i);

Why not start using of_get_cpu_state_node here which was introduced in
earlier patch as part of this simplification ?

--
Regards,
Sudeep