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

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Message-ID: <537C7348.7060202@arm.com>
Date:	Wed, 21 May 2014 10:35:04 +0100
From:	Sudeep Holla <sudeep.holla@....com>
To:	Viresh Kumar <viresh.kumar@...aro.org>,
	"rjw@...ysocki.net" <rjw@...ysocki.net>
CC:	Sudeep Holla <sudeep.holla@....com>,
	"linaro-kernel@...ts.linaro.org" <linaro-kernel@...ts.linaro.org>,
	"linux-pm@...r.kernel.org" <linux-pm@...r.kernel.org>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	Arvind Chauhan <Arvind.Chauhan@....com>,
	"inderpal.s@...sung.com" <inderpal.s@...sung.com>,
	"pavel@....cz" <pavel@....cz>, "nm@...com" <nm@...com>,
	"chander.kashyap@...aro.org" <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>
Subject: Re: [PATCH Resend] driver/core: cpu: initialize opp table



On 19/05/14 07:29, 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().
>

This is really nice getting rid of all duplicate code.

> 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)
> +	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)

As Rafael mentioned it's better to have a wrapper function to hide these
details. You should consider the fact that of_init_opp_table returns -EINVAL if
CONFIG_PM_OPP not defined as well as when the list is invalid in the DT.
IMO we can return -ENOSYS if not implemented(i.e. !CONFIG_PM_OPP)

> +				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;
>   }
>

Regards,
Sudeep


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