linux-kernel - Re: [PATCH 2/4] power: reset: at91-poweroff: move shdwc related data to one structure

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Message-ID: <a0db3b8a-3c2b-02fd-64cc-b490a75b8b7c@microchip.com>
Date:   Thu, 6 Dec 2018 09:48:10 +0000
From:   <Claudiu.Beznea@...rochip.com>
To:     <sebastian.reichel@...labora.com>, <alexandre.belloni@...tlin.com>
CC:     <linux-kernel@...r.kernel.org>, <linux-pm@...r.kernel.org>,
        <linux-arm-kernel@...ts.infradead.org>
Subject: Re: [PATCH 2/4] power: reset: at91-poweroff: move shdwc related data
 to one structure

Hi Sebastian,

On 06.12.2018 00:40, Sebastian Reichel wrote:
> Hi,
> 
> On Wed, Nov 07, 2018 at 06:23:40PM +0100, Alexandre Belloni wrote:
>> On 07/11/2018 14:54:17+0000, Claudiu.Beznea@...rochip.com wrote:
>>> Hi Alexandre,
>>>
>>> On 06.11.2018 23:09, Alexandre Belloni wrote:
>>>> Hi Claudiu,
>>>>
>>>> On 05/11/2018 11:14:26+0000, Claudiu.Beznea@...rochip.com wrote:
>>>>>  static int __init at91_poweroff_probe(struct platform_device *pdev)
>>>>> @@ -154,16 +160,22 @@ static int __init at91_poweroff_probe(struct platform_device *pdev)
>>>>>  	u32 ddr_type;
>>>>>  	int ret;
>>>>>  
>>>>> +	at91_shdwc = devm_kzalloc(&pdev->dev, sizeof(*at91_shdwc), GFP_KERNEL);
>>>>> +	if (!at91_shdwc)
>>>>> +		return -ENOMEM;
>>>>> +
>>>>
>>>> Is there any real benefit that will offset the time lost for that
>>>> allocation at boot time?
>>>
>>> No, I haven't run benchmarks on this. I only wanted to have them grouped in
>>> one structure. Please let me know if you have some tests in mind.
>>>
>>
>> Well, it is probably not much but small things adds up. Having it as a
>> global structure is probably good enough.
> 
> I suppose I will get a new patch with this change?

Yes, I will send a new version for this one.

Thank you,
Claudiu Beznea

> 
> -- Sebastian
> 
>>
>>>>
>>>> I understand you are then testing at91_shdwc to know whether the driver
>>>> already probed once. But, the driver will never probe twice as there is
>>>> only one shutdown controller on the SoC and anyway, If it was to probe
>>>> twice, it will still work as expected.
>>>
>>> I had in mind the scenario where the driver would be compiled as module. I
>>> know insmod already does this checking. I'm ok to remove this checking. I
>>> will do it in next version. With this I will also remove devm_kzalloc() of
>>> at91_shdwc.
>>>
>>
>> Thanks,
>>
>> -- 
>> Alexandre Belloni, Bootlin
>> Embedded Linux and Kernel engineering
>> https://bootlin.com