linux-kernel - Re: [PATCH V2 3/7] driver/core: cpu: initialize opp table

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Date:	Wed, 21 May 2014 14:45:31 +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>,
	"nm@...com" <nm@...com>,
	"chander.kashyap@...aro.org" <chander.kashyap@...aro.org>,
	"pavel@....cz" <pavel@....cz>,
	"len.brown@...el.com" <len.brown@...el.com>,
	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 V2 3/7] driver/core: cpu: initialize opp table



On 21/05/14 12:10, 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>
> Signed-off-by: Viresh Kumar <viresh.kumar@...aro.org>
> ---
>   drivers/base/cpu.c | 30 ++++++++++++++++++++++++++----
>   1 file changed, 26 insertions(+), 4 deletions(-)
>
> diff --git a/drivers/base/cpu.c b/drivers/base/cpu.c
> index 006b1bc..853e99e 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"
>
> @@ -322,6 +323,25 @@ static int cpu_uevent(struct device *dev, struct kobj_uevent_env *env)
>   }
>   #endif
>
> +#if defined(CONFIG_PM_OPP) && defined(CONFIG_OF)
> +static inline void of_init_cpu_opp_table(struct cpu *cpu)
> +{
> +	int error;
> +
> +	/* Initialize CPU's OPP table */
> +	error = of_init_opp_table(&cpu->dev);
> +	if (!error)
> +		dev_info(&cpu->dev, "%s: created OPP table for cpu: %d\n",
> +			 __func__, cpu->dev.id);

[Nit] Not sure if we need this logging on each cpu, may be dev_dbg if you still
fancy one ? :)

> +	/* Print error only if there is an issue with OPP table */
> +	else if (error != -ENOSYS && error != -ENODEV)
> +		dev_err(&cpu->dev, "%s: failed to init OPP table for cpu%d, err: %d\n",
> +			__func__, cpu->dev.id, error);
> +}
> +#else
> +static inline void of_init_cpu_opp_table(struct cpu *cpu) {}
> +#endif
> +

IMO this could be more generic and applicable for any device if you replace
"struct cpu" with "struct device". I know this is currently used by cpu but
we can extend it's use for any device if needed in future. You can then move
this to pm_opp.h as of_init_dev_opp_table may be.

Regards,
Sudeep

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