linux-kernel - Re: [PATCH Resend] driver/core: cpu: initialize opp table

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Date:	Mon, 19 May 2014 23:13:24 +0200
From:	"Rafael J. Wysocki" <rjw@...ysocki.net>
To:	Viresh Kumar <viresh.kumar@...aro.org>
Cc:	linaro-kernel@...ts.linaro.org, linux-pm@...r.kernel.org,
	linux-kernel@...r.kernel.org, arvind.chauhan@....com,
	inderpal.s@...sung.com, pavel@....cz, nm@...com,
	chander.kashyap@...aro.org,
	Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
	Amit Daniel Kachhap <amit.daniel@...sung.com>,
	Kukjin Kim <kgene.kim@...sung.com>,
	Shawn Guo <shawn.guo@...aro.org>,
	Sudeep Holla <sudeep.holla@....com>
Subject: Re: [PATCH Resend] driver/core: cpu: initialize opp table

On Monday, May 19, 2014 11:59:11 AM Viresh Kumar wrote:
> All drivers expecting CPU's OPPs from device tree initialize OPP table using
> of_init_opp_table() and there is nothing driver specific in that. They all do it
> in the same way adding to code redundancy.
> 
> It would be better if we can get rid of code redundancy by initializing CPU OPPs
> from core code for all CPUs that have a "operating-points" property defined in
> their node.
> 
> This patch initializes OPPs as soon as CPU device is registered in
> register_cpu().
> 
> Cc: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
> Cc: Amit Daniel Kachhap <amit.daniel@...sung.com>
> Cc: Kukjin Kim <kgene.kim@...sung.com>
> Cc: Shawn Guo <shawn.guo@...aro.org>
> Cc: Sudeep Holla <sudeep.holla@....com>
> Signed-off-by: Viresh Kumar <viresh.kumar@...aro.org>
> ---
> V1-V2:
> A colleague spotted some extra debug prints in my first mail :(
> 
> Replace
> + pr_err("****%s: failed to init OPP table for cpu%d, err: %d\n",
> with
> + pr_err("%s: failed to init OPP table for cpu%d, err: %d\n",
> 
>  drivers/base/cpu.c | 14 ++++++++++++--
>  1 file changed, 12 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/base/cpu.c b/drivers/base/cpu.c
> index 006b1bc..74ce944 100644
> --- a/drivers/base/cpu.c
> +++ b/drivers/base/cpu.c
> @@ -16,6 +16,7 @@
>  #include <linux/acpi.h>
>  #include <linux/of.h>
>  #include <linux/cpufeature.h>
> +#include <linux/pm_opp.h>
>  
>  #include "base.h"
>  
> @@ -349,11 +350,20 @@ int register_cpu(struct cpu *cpu, int num)
>  	if (cpu->hotpluggable)
>  		cpu->dev.groups = hotplugable_cpu_attr_groups;
>  	error = device_register(&cpu->dev);
> -	if (!error)

What about

	if (error)
		return error;

and then you'd save an indentation level?

Anyway, I find adding of_node* stuff directly to the driver core this way
kind of disgusting as there still are platforms that don't use it.

Can we have a call to a function that will change into an empty stub on such
platforms here, please?

> +	if (!error) {
>  		per_cpu(cpu_sys_devices, num) = &cpu->dev;
> -	if (!error)
>  		register_cpu_under_node(num, cpu_to_node(num));
>  
> +		/* Initialize CPUs OPP table */
> +		if (of_node_get(cpu->dev.of_node)) {
> +			error = of_init_opp_table(&cpu->dev);
> +			if (error && error != -ENODEV)
> +				pr_err("%s: failed to init OPP table for cpu%d, err: %d\n",
> +					__func__, num, error);
> +			of_node_put(cpu->dev.of_node);
> +		}
> +	}
> +
>  	return error;
>  }
>  
> 

-- 
I speak only for myself.
Rafael J. Wysocki, Intel Open Source Technology Center.
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