linux-kernel - Re: [PATCH 2/3] ACPI / PM: Make messages in acpi_device_set

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Message-ID: <1858303.iaJrUSpF87@vostro.rjw.lan>
Date:	Wed, 31 Jul 2013 12:27:53 +0200
From:	"Rafael J. Wysocki" <rjw@...k.pl>
To:	Aaron Lu <aaron.lu@...el.com>
Cc:	ACPI Devel Maling List <linux-acpi@...r.kernel.org>,
	LKML <linux-kernel@...r.kernel.org>,
	Linux PM list <linux-pm@...r.kernel.org>,
	Yinghai Lu <yinghai@...nel.org>,
	Bjorn Helgaas <bhelgaas@...gle.com>, Tejun Heo <tj@...nel.org>,
	linux-ide@...r.kernel.org
Subject: Re: [PATCH 2/3] ACPI / PM: Make messages in acpi_device_set_power() print device names

On Wednesday, July 31, 2013 02:52:53 PM Aaron Lu wrote:
> On 07/29/2013 08:20 PM, Rafael J. Wysocki wrote:
> > On Monday, July 29, 2013 10:29:36 AM Aaron Lu wrote:
> >> On 07/27/2013 09:11 PM, Rafael J. Wysocki wrote:
> >>> From: Rafael J. Wysocki <rafael.j.wysocki@...el.com>
> >>>
> >>> Modify acpi_device_set_power() so that diagnostic messages printed by
> >>> it to the kernel log always contain the name of the device concerned
> >>> to make it possible to identify the device that triggered the message
> >>> if need be.
> >>>
> >>> Also replace printk(KERN_WARNING ) with dev_warn() everywhere in that
> >>> function.
> >>>
> >>> Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@...el.com>
> >>> ---
> >>>  drivers/acpi/device_pm.c |   22 ++++++++++------------
> >>>  1 file changed, 10 insertions(+), 12 deletions(-)
> >>>
> >>> Index: linux-pm/drivers/acpi/device_pm.c
> >>> ===================================================================
> >>> --- linux-pm.orig/drivers/acpi/device_pm.c
> >>> +++ linux-pm/drivers/acpi/device_pm.c
> >>> @@ -166,20 +166,20 @@ int acpi_device_set_power(struct acpi_de
> >>>  	/* Make sure this is a valid target state */
> >>>  
> >>>  	if (state == device->power.state) {
> >>> -		ACPI_DEBUG_PRINT((ACPI_DB_INFO, "Device is already at %s\n",
> >>> +		ACPI_DEBUG_PRINT((ACPI_DB_INFO, "Device [%s] already in %s\n",
> >>> +				  device->pnp.bus_id,
> >>>  				  acpi_power_state_string(state)));
> >>>  		return 0;
> >>>  	}
> >>>  
> >>>  	if (!device->power.states[state].flags.valid) {
> >>> -		printk(KERN_WARNING PREFIX "Device does not support %s\n",
> >>> -		       acpi_power_state_string(state));
> >>> +		dev_warn(&device->dev, "Power state %s not supported\n",
> >>> +			 acpi_power_state_string(state));
> >>>  		return -ENODEV;
> >>>  	}
> >>>  	if (device->parent && (state < device->parent->power.state)) {
> >>> -		printk(KERN_WARNING PREFIX
> >>> -			      "Cannot set device to a higher-powered"
> >>> -			      " state than parent\n");
> >>> +		dev_warn(&device->dev, "Cannot transition to a higher-powered "
> >>> +			 "state than parent\n");
> >>
> >> I think the state information would also be useful here:
> >>
> >> 		dev_warn(&device->dev, "Cannot transition to a higher-powereed "
> >> 		         "state %d than paeren's state %d\n", state,
> >> 			 device->parent->power.state);
> > 
> > This is not the scope of this patch, please send another one on top of it.
> > 
> 
> Patch to add state information in error message, apply on top of this
> one.
> 
> From: Aaron Lu <aaron.lu@...el.com>
> Subject: [PATCH] ACPI / PM: Add state information in error message for
>  acpi_device_set_power
> 
> The state information can be useful to know what the problem is when it
> appeared in an error message about a device can not being set to a higher
> power state than its parent, so this patch adds such state information
> for both the target state of the device failed to be set and the current
> parent's state.
> 
> Signed-off-by: Aaron Lu <aaron.lu@...el.com>
> ---
>  drivers/acpi/device_pm.c | 3 ++-
>  1 file changed, 2 insertions(+), 1 deletion(-)
> 
> diff --git a/drivers/acpi/device_pm.c b/drivers/acpi/device_pm.c
> index beb9625..707258b 100644
> --- a/drivers/acpi/device_pm.c
> +++ b/drivers/acpi/device_pm.c
> @@ -179,7 +179,8 @@ int acpi_device_set_power(struct acpi_device *device, int state)
>  	}
>  	if (device->parent && (state < device->parent->power.state)) {
>  		dev_warn(&device->dev,
> -			 "Cannot transition to a higher-powered state than parent\n");
> +			 "Cannot transition to a higher-powered state %d than parent's state %d\n",

This message will look a little odd I think ->

> +			 state, device->parent->power.state);

-> and please don't use raw numbers in such messages.

What about

	"Cannot transition to power state %s for parent in %s\n",
	acpi_power_state_string(state),
	acpi_power_state_string(device->parent->power.state)

>  		return -ENODEV;
>  	}

Thanks,
Rafael


-- 
I speak only for myself.
Rafael J. Wysocki, Intel Open Source Technology Center.
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