linux-kernel - Re: [PATCH] power: reset: use restart_notifier mechanism for msm poweroff

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Date:	Fri, 19 Sep 2014 06:53:09 -0700
From:	Guenter Roeck <linux@...ck-us.net>
To:	Pramod Gurav <pramod.gurav@...rtplayin.com>,
	linux-kernel@...r.kernel.org, linux-arm-msm@...r.kernel.org
CC:	Josh Cartwright <joshc@...eaurora.org>,
	Sebastian Reichel <sre@...nel.org>,
	Dmitry Eremin-Solenikov <dbaryshkov@...il.com>,
	David Woodhouse <dwmw2@...radead.org>,
	Stephen Boyd <sboyd@...eaurora.org>, linux-pm@...r.kernel.org
Subject: Re: [PATCH] power: reset: use restart_notifier mechanism for msm
 poweroff

On 09/19/2014 05:06 AM, Pramod Gurav wrote:
> This change uses replaces use of arm_pm_restart with recently introduced
> reset mechanism in Linux kernel called restart_notifier.
>
> Cc: Guenter Roeck <linux@...ck-us.net>
> Cc: Josh Cartwright <joshc@...eaurora.org>
> Cc: Sebastian Reichel <sre@...nel.org>
> Cc: Dmitry Eremin-Solenikov <dbaryshkov@...il.com>
> Cc: David Woodhouse <dwmw2@...radead.org>
> Cc: Stephen Boyd <sboyd@...eaurora.org>
> Cc: linux-pm@...r.kernel.org
>
> Signed-off-by: Pramod Gurav <pramod.gurav@...rtplayin.com>
>
> ---
>
> This patch is tested on DB8074 Target and are based on patchset [1]
> by Guenter Roeck.
>
> [1]: https://patchwork.kernel.org/patch/4746721/
>
>   drivers/power/reset/msm-poweroff.c |   18 +++++++++++++++---
>   1 file changed, 15 insertions(+), 3 deletions(-)
>
> diff --git a/drivers/power/reset/msm-poweroff.c b/drivers/power/reset/msm-poweroff.c
> index 774f9a3..59b368c 100644
> --- a/drivers/power/reset/msm-poweroff.c
> +++ b/drivers/power/reset/msm-poweroff.c
> @@ -24,17 +24,21 @@
>   #include <asm/system_misc.h>
>
>   static void __iomem *msm_ps_hold;
> +static struct notifier_block restart_nb;
>
> -static void do_msm_restart(enum reboot_mode reboot_mode, const char *cmd)
> +static int do_msm_restart(struct notifier_block *nb, unsigned long action,
> +			   void *data)
>   {
>   	writel(0, msm_ps_hold);
>   	mdelay(10000);
> +
> +	return NOTIFY_DONE;
>   }
>
>   static void do_msm_poweroff(void)
>   {
>   	/* TODO: Add poweroff capability */
> -	do_msm_restart(REBOOT_HARD, NULL);
> +	do_msm_restart(&restart_nb, 0, NULL);
>   }
>
>   static int msm_restart_probe(struct platform_device *pdev)
> @@ -47,8 +51,16 @@ static int msm_restart_probe(struct platform_device *pdev)
>   	if (IS_ERR(msm_ps_hold))
>   		return PTR_ERR(msm_ps_hold);
>
> +	restart_nb.notifier_call = do_msm_restart;
> +	restart_nb.priority = 128;

Since the structure is static, you might as well initialize it there
and save a few bytes of code.

> +	if (register_restart_handler(&restart_nb)) {
> +		dev_err(&pdev->dev,
> +			"failed to setup restart handler.\n");

'failed to register ...' might be a bit better wording.

> +			restart_nb.notifier_call = NULL;

No need to set notifier_call to NULL.

> +	}
> +
>   	pm_power_off = do_msm_poweroff;
> -	arm_pm_restart = do_msm_restart;
> +
>   	return 0;
>   }
>
>

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