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

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Message-ID: <20181107172340.GF21694@piout.net>
Date:   Wed, 7 Nov 2018 18:23:40 +0100
From:   Alexandre Belloni <alexandre.belloni@...tlin.com>
To:     Claudiu.Beznea@...rochip.com
Cc:     linux-kernel@...r.kernel.org, linux-pm@...r.kernel.org,
        sre@...nel.org, linux-arm-kernel@...ts.infradead.org
Subject: Re: [PATCH 2/4] power: reset: at91-poweroff: move shdwc related data
 to one structure

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. Havinf it as a
global structure is probably good enough.

> > 
> > 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