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From: Alexandre Belloni <alexandre.belloni@bootlin.com>
To: Claudiu.Beznea@microchip.com
Cc: linux-kernel@vger.kernel.org, Ludovic.Desroches@microchip.com,
	linux-arm-kernel@lists.infradead.org, wenyou.yang@atmel.com
Subject: Re: [PATCH v2 2/3] ARM: at91: pm: add per soc validation of pm modes
Date: Tue, 4 Aug 2020 17:08:41 +0200	[thread overview]
Message-ID: <20200804150841.GA10725@piout.net> (raw)
In-Reply-To: <f9e1d923-225e-7a18-ed48-c8c7e7d4d8cf@microchip.com>

On 04/08/2020 15:00:38+0000, Claudiu.Beznea@microchip.com wrote:
> 
> 
> On 04.08.2020 14:42, Alexandre Belloni wrote:
> > EXTERNAL EMAIL: Do not click links or open attachments unless you know the content is safe
> > 
> > Hello,
> > 
> > On 04/08/2020 14:07:37+0300, Claudiu Beznea wrote:
> >>  void __init at91rm9200_pm_init(void)
> >>  {
> >> +     static const int modes[] __initconst = {
> > 
> > You don't need that to be static as it is now local to the function.
> > 
> >> +             AT91_PM_STANDBY, AT91_PM_ULP0
> >> +     };
> >> +
> >>       if (!IS_ENABLED(CONFIG_SOC_AT91RM9200))
> >>               return;
> >>
> >> +     at91_pm_modes_validate(modes, ARRAY_SIZE(modes));
> > 
> > For rm9200 and at91sam9, I would not allow changing the pm_modes and
> > simply enforce standby_mode = AT91_PM_STANDBY and suspend_mode =
> > AT91_PM_ULP0.I don't think you have any user that ever changed that
> > behaviour also that avoids increasing the boot time for those slow SoCs.
> 
> OK, but bootargs is parsed at a moment when there is no information about
> the machine that is running the code. And enforcing this in *_pm_init()
> functions for rm9200 and at91sam9 may change suspend and standby mode that
> user selected. If there is no user up to this moment there is still the
> possibility of being one in the future.
> 

So let's prevent users from doing that. Unused arguments are silently
ignored which is exactly what we want to do. You won't make me believe
there is actually a use case for swapping the standby and suspend
meanings.

-- 
Alexandre Belloni, Bootlin
Embedded Linux and Kernel engineering
https://bootlin.com

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http://lists.infradead.org/mailman/listinfo/linux-arm-kernel

WARNING: multiple messages have this Message-ID (diff)
From: Alexandre Belloni <alexandre.belloni@bootlin.com>
To: Claudiu.Beznea@microchip.com
Cc: Nicolas.Ferre@microchip.com, Ludovic.Desroches@microchip.com,
	wenyou.yang@atmel.com, linux-arm-kernel@lists.infradead.org,
	linux-kernel@vger.kernel.org
Subject: Re: [PATCH v2 2/3] ARM: at91: pm: add per soc validation of pm modes
Date: Tue, 4 Aug 2020 17:08:41 +0200	[thread overview]
Message-ID: <20200804150841.GA10725@piout.net> (raw)
In-Reply-To: <f9e1d923-225e-7a18-ed48-c8c7e7d4d8cf@microchip.com>

On 04/08/2020 15:00:38+0000, Claudiu.Beznea@microchip.com wrote:
> 
> 
> On 04.08.2020 14:42, Alexandre Belloni wrote:
> > EXTERNAL EMAIL: Do not click links or open attachments unless you know the content is safe
> > 
> > Hello,
> > 
> > On 04/08/2020 14:07:37+0300, Claudiu Beznea wrote:
> >>  void __init at91rm9200_pm_init(void)
> >>  {
> >> +     static const int modes[] __initconst = {
> > 
> > You don't need that to be static as it is now local to the function.
> > 
> >> +             AT91_PM_STANDBY, AT91_PM_ULP0
> >> +     };
> >> +
> >>       if (!IS_ENABLED(CONFIG_SOC_AT91RM9200))
> >>               return;
> >>
> >> +     at91_pm_modes_validate(modes, ARRAY_SIZE(modes));
> > 
> > For rm9200 and at91sam9, I would not allow changing the pm_modes and
> > simply enforce standby_mode = AT91_PM_STANDBY and suspend_mode =
> > AT91_PM_ULP0.I don't think you have any user that ever changed that
> > behaviour also that avoids increasing the boot time for those slow SoCs.
> 
> OK, but bootargs is parsed at a moment when there is no information about
> the machine that is running the code. And enforcing this in *_pm_init()
> functions for rm9200 and at91sam9 may change suspend and standby mode that
> user selected. If there is no user up to this moment there is still the
> possibility of being one in the future.
> 

So let's prevent users from doing that. Unused arguments are silently
ignored which is exactly what we want to do. You won't make me believe
there is actually a use case for swapping the standby and suspend
meanings.

-- 
Alexandre Belloni, Bootlin
Embedded Linux and Kernel engineering
https://bootlin.com

  reply	other threads:[~2020-08-04 15:10 UTC|newest]

Thread overview: 18+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-08-04 11:07 [PATCH v2 0/3] AT91 PM improvements Claudiu Beznea
2020-08-04 11:07 ` Claudiu Beznea
2020-08-04 11:07 ` [PATCH v2 1/3] ARM: at91: pm: add support for ULP0 fast wakeup Claudiu Beznea
2020-08-04 11:07   ` Claudiu Beznea
2020-08-04 11:07 ` [PATCH v2 2/3] ARM: at91: pm: add per soc validation of pm modes Claudiu Beznea
2020-08-04 11:07   ` Claudiu Beznea
2020-08-04 11:42   ` Alexandre Belloni
2020-08-04 11:42     ` Alexandre Belloni
2020-08-04 15:00     ` Claudiu.Beznea
2020-08-04 15:00       ` Claudiu.Beznea
2020-08-04 15:08       ` Alexandre Belloni [this message]
2020-08-04 15:08         ` Alexandre Belloni
2020-08-04 15:45         ` Claudiu.Beznea
2020-08-04 15:45           ` Claudiu.Beznea
2020-08-04 15:56           ` Alexandre Belloni
2020-08-04 15:56             ` Alexandre Belloni
2020-08-04 11:07 ` [PATCH v2 3/3] ARM: at91: pm: of_node_put() after its usage Claudiu Beznea
2020-08-04 11:07   ` Claudiu Beznea

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