linux-kernel - Re: [PATCH v5 02/15] clk: at91: pmc: execute suspend/resume only for backup mode

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Message-ID: <ae6e6277-8ca0-100d-56e5-cd7591deee95@microchip.com>
Date:   Fri, 15 Oct 2021 09:51:44 +0200
From:   Nicolas Ferre <nicolas.ferre@...rochip.com>
To:     Claudiu Beznea <claudiu.beznea@...rochip.com>,
        <mturquette@...libre.com>, <sboyd@...nel.org>,
        <alexandre.belloni@...tlin.com>, <ludovic.desroches@...rochip.com>
CC:     <linux-clk@...r.kernel.org>,
        <linux-arm-kernel@...ts.infradead.org>,
        <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH v5 02/15] clk: at91: pmc: execute suspend/resume only for
 backup mode

On 11/10/2021 at 13:27, Claudiu Beznea wrote:
> Before going to backup mode architecture specific PM code sets the first
> word in securam (file arch/arm/mach-at91/pm.c, function at91_pm_begin()).
> Thus take this into account when suspending/resuming clocks. This will
> avoid executing unnecessary instructions when suspending to non backup
> modes.
> 
> Signed-off-by: Claudiu Beznea <claudiu.beznea@...rochip.com>

Ok to do it like this:
Acked-by: Nicolas Ferre <nicolas.ferre@...rochip.com>


> ---
>   drivers/clk/at91/pmc.c | 39 +++++++++++++++++++++++++++++++++++++++
>   1 file changed, 39 insertions(+)
> 
> diff --git a/drivers/clk/at91/pmc.c b/drivers/clk/at91/pmc.c
> index b2806946a77a..517973062719 100644
> --- a/drivers/clk/at91/pmc.c
> +++ b/drivers/clk/at91/pmc.c
> @@ -8,6 +8,7 @@
>   #include <linux/clkdev.h>
>   #include <linux/clk/at91_pmc.h>
>   #include <linux/of.h>
> +#include <linux/of_address.h>
>   #include <linux/mfd/syscon.h>
>   #include <linux/platform_device.h>
>   #include <linux/regmap.h>
> @@ -110,13 +111,35 @@ struct pmc_data *pmc_data_allocate(unsigned int ncore, unsigned int nsystem,
>   }
>   
>   #ifdef CONFIG_PM
> +
> +/* Address in SECURAM that say if we suspend to backup mode. */
> +static void __iomem *at91_pmc_backup_suspend;
> +
>   static int at91_pmc_suspend(void)
>   {
> +	unsigned int backup;
> +
> +	if (!at91_pmc_backup_suspend)
> +		return 0;
> +
> +	backup = readl_relaxed(at91_pmc_backup_suspend);
> +	if (!backup)
> +		return 0;
> +
>   	return clk_save_context();
>   }
>   
>   static void at91_pmc_resume(void)
>   {
> +	unsigned int backup;
> +
> +	if (!at91_pmc_backup_suspend)
> +		return;
> +
> +	backup = readl_relaxed(at91_pmc_backup_suspend);
> +	if (!backup)
> +		return;
> +
>   	clk_restore_context();
>   }
>   
> @@ -144,6 +167,22 @@ static int __init pmc_register_ops(void)
>   	}
>   	of_node_put(np);
>   
> +	np = of_find_compatible_node(NULL, NULL, "atmel,sama5d2-securam");
> +	if (!np)
> +		return -ENODEV;
> +
> +	if (!of_device_is_available(np)) {
> +		of_node_put(np);
> +		return -ENODEV;
> +	}
> +	of_node_put(np);
> +
> +	at91_pmc_backup_suspend = of_iomap(np, 0);
> +	if (!at91_pmc_backup_suspend) {
> +		pr_warn("%s(): unable to map securam\n", __func__);
> +		return -ENOMEM;
> +	}
> +
>   	register_syscore_ops(&pmc_syscore_ops);
>   
>   	return 0;
> 


-- 
Nicolas Ferre