linux-kernel - Re: [PATCH v3] power: reset: use restart

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Date:	Tue, 23 Sep 2014 12:48:42 -0500
From:	Kumar Gala <galak@...eaurora.org>
To:	Pramod Gurav <pramod.gurav@...rtplayin.com>
Cc:	linux-kernel@...r.kernel.org, Guenter Roeck <linux@...ck-us.net>,
	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,
	linux-arm-msm <linux-arm-msm@...r.kernel.org>
Subject: Re: [PATCH v3] power: reset: use restart_notifier mechanism for msm-poweroff


On Sep 23, 2014, at 1:28 AM, Pramod Gurav <pramod.gurav@...rtplayin.com> wrote:

> +linux-arm-msm
> On Tuesday 23 September 2014 11:38 AM, Pramod Gurav wrote:
>> This change replaces use of arm_pm_restart with recently introduced
>> reset mechanism in Linux kernel called restart_notifier.

Can you update the commit message to include details about the priority level we are setting it to.

Probably something like Josh had:

Choose priority 128, as according to documentation, this mechanism "is
sufficient to restart the entire system”.

Hmm, what happens if we have ps_hold restart and msm-poweroff enabled.  Which one should have priority?

>> 
>> Reviewed-by: Guenter Roeck <linux@...ck-us.net>
>> 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>
>> ---
>> Tested on Dragonboard APQ8074
>> 
>> Changes since v2:
>> - Removed unwanted header file and added linux/pm.h
>> 
>> Changes since v1:
>> - Initialized restart_nb with its declaration
>> - Removed return check for register_restart_handler as it always
>>  returns 0 as per Guenter's suggestion to Josh's similar patch.
>>  This takes care of Guenter's comments on error logs and NULL
>>  initialization of restart_nb.notifier_call.
>> ---
>> drivers/power/reset/msm-poweroff.c |   20 ++++++++++++++------
>> 1 file changed, 14 insertions(+), 6 deletions(-)
>> 
>> diff --git a/drivers/power/reset/msm-poweroff.c b/drivers/power/reset/msm-poweroff.c
>> index 774f9a3..4702efd 100644
>> --- a/drivers/power/reset/msm-poweroff.c
>> +++ b/drivers/power/reset/msm-poweroff.c
>> @@ -20,21 +20,27 @@
>> #include <linux/platform_device.h>
>> #include <linux/module.h>
>> #include <linux/reboot.h>
>> -
>> -#include <asm/system_misc.h>
>> +#include <linux/pm.h>
>> 
>> static void __iomem *msm_ps_hold;
>> -
>> -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 struct notifier_block restart_nb = {
>> +	.notifier_call = do_msm_restart,
>> +	.priority = 128,
>> +};
>> +
>> 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 +53,10 @@ static int msm_restart_probe(struct platform_device *pdev)
>> 	if (IS_ERR(msm_ps_hold))
>> 		return PTR_ERR(msm_ps_hold);
>> 
>> +	register_restart_handler(&restart_nb);
>> +
>> 	pm_power_off = do_msm_poweroff;
>> -	arm_pm_restart = do_msm_restart;
>> +
>> 	return 0;
>> }
>> 
>> 
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