linux-kernel - Re: [PATCH 2/6] ARM: cpuidle: Add a cpuidle ops structure to be used for DT

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <550809A7.3020600@linaro.org>
Date:	Tue, 17 Mar 2015 12:01:59 +0100
From:	Daniel Lezcano <daniel.lezcano@...aro.org>
To:	Lorenzo Pieralisi <lorenzo.pieralisi@....com>
CC:	"rjw@...ysocki.net" <rjw@...ysocki.net>,
	"linux-pm@...r.kernel.org" <linux-pm@...r.kernel.org>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	Catalin Marinas <Catalin.Marinas@....com>,
	"robherring2@...il.com" <robherring2@...il.com>,
	"arnd@...db.de" <arnd@...db.de>,
	"devicetree@...r.kernel.org" <devicetree@...r.kernel.org>,
	"linux-arm-kernel@...ts.infradead.org" 
	<linux-arm-kernel@...ts.infradead.org>,
	"lina.iyer@...aro.org" <lina.iyer@...aro.org>
Subject: Re: [PATCH 2/6] ARM: cpuidle: Add a cpuidle ops structure to be used
 for DT

On 03/16/2015 07:16 PM, Lorenzo Pieralisi wrote:
> On Tue, Mar 03, 2015 at 12:29:33PM +0000, Daniel Lezcano wrote:
>> The current state of the different cpuidle drivers is the different PM
>
> Nit: "The current state of cpuidle drivers is such that different ..."

Ok.

>> operations are passed via the platform_data using the platform driver
>> paradigm.
>>
>> This approach allowed to split the low level PM code from the arch specific
>> and the generic cpuidle code.
>>
>> Unfortunately there are complains about this approach as, in the context of the
>
> Nit: s/complains/complaints

Ok.

[ ... ]

>> @@ -27,4 +27,14 @@ static inline int arm_cpuidle_simple_enter(struct cpuidle_device *dev,
>>    */
>>   #define ARM_CPUIDLE_WFI_STATE ARM_CPUIDLE_WFI_STATE_PWR(UINT_MAX)
>>
>> +struct cpuidle_ops {
>> +	const char *name;
>> +	int (*suspend)(int cpu, unsigned long arg);
>> +	int (*init)(struct device_node *, int cpu);
>> +};
>> +
>> +extern int arm_cpuidle_suspend(int index);
>> +
>> +extern int arm_cpuidle_init(int cpu);
>
> idle_cpu_suspend()
> idle_cpu_init()
>
> ?
>
> I am really not fussed about the naming.
>
> To make this and x86 driver name compliant (well, function signatures
> are a bit different) we could use:
>
> arm_idle()
> arm_idle_cpu_init()
>
> even though I think the arch prefix is useless.
>
> Side note: why is the x86 driver in drivers/idle ? To have another dir :) ?

I believe it is there for historical reasons.

[ ... ]

>> +static struct cpuidle_ops cpuidle_ops[NR_CPUS];
>
> That's because you want platform cpuidle_ops to be __initdata ?

Yes.

> It should not be a big overhead on arm32 to have a number of
> structs equal to NR_CPUS, on arm64 it is the other way around
> there are few cpu_ops, but number of CPUs can be high so it
> is an array of pointers.
>
> I think it is ok to leave it as it is (or probably make cpuidle_ops
> a single struct, I expect enable-method to be common across cpus).

I prefer to keep per cpu because I am not sure of this assumption.

[ ... ]

>> +	cpuidle_ops[cpu] = *ops; /* structure copy */
>
> See above.
>
>> +
>> +	pr_notice("cpuidle: enable-method property '%s'"
>> +		  " found operations\n", ops->name);
>> +
>> +	return 0;
>> +}
>> +
>> +int __init arm_cpuidle_init(int cpu)
>> +{
>> +	int ret = -EOPNOTSUPP;
>
> Nit: You always assign ret, so there is no point in initializing it.

Ok, I will fix it.

Thanks for reviewing.

   -- Daniel



-- 
  <http://www.linaro.org/> Linaro.org │ Open source software for ARM SoCs

Follow Linaro:  <http://www.facebook.com/pages/Linaro> Facebook |
<http://twitter.com/#!/linaroorg> Twitter |
<http://www.linaro.org/linaro-blog/> Blog

--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/