linux-kernel - Re: [PATCH] ACPI: evaluate

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Date:	Tue, 24 Apr 2012 11:10:11 +0800
From:	Aaron Lu <aaron.lu@....com>
To:	Lin Ming <ming.m.lin@...el.com>
CC:	"Rafael J. Wysocki" <rjw@...k.pl>, Len Brown <lenb@...nel.org>,
	<linux-acpi@...r.kernel.org>, <linux-pm@...r.kernel.org>,
	<linux-kernel@...r.kernel.org>, Zhang Rui <rui.zhang@...el.com>,
	Andiry Xu <andiry.xu@....com>, Alex He <alex.he@....com>
Subject: Re: [PATCH] ACPI: evaluate _PS3 when entering D3 Cold

On Tue, Apr 24, 2012 at 10:29:36AM +0800, Lin Ming wrote:
> On Tue, 2012-04-24 at 10:07 +0800, Aaron Lu wrote:
> > On Mon, Apr 23, 2012 at 09:50:57PM +0200, Rafael J. Wysocki wrote:
> > > > diff --git a/drivers/acpi/bus.c b/drivers/acpi/bus.c
> > > > index 3263b68..187433f 100644
> > > > --- a/drivers/acpi/bus.c
> > > > +++ b/drivers/acpi/bus.c
> > > > @@ -273,6 +273,9 @@ static int __acpi_bus_set_power(struct acpi_device *device, int state)
> > > >  		}
> > > >  	} else {
> > > >  		if (device->power.states[state].flags.explicit_set) {
> > > > +			/* evaluate _PS3 instead of _PS4 when entering D3Cold */
> > > > +			if (state == ACPI_STATE_D3)
> > > > +				object_name[3] -= 1;
> > > 
> > > Can you just put '3' here directly?  That'll be much cleaner than the
> > > subtraction (that could have been -- as well).
> > > 
> > > >  			status = acpi_evaluate_object(device->handle,
> > > >  						      object_name, NULL, NULL);
> > > >  			if (ACPI_FAILURE(status)) {
> > > > diff --git a/drivers/acpi/scan.c b/drivers/acpi/scan.c
> > > > index 7417267..de2ae10 100644
> > > > --- a/drivers/acpi/scan.c
> > > > +++ b/drivers/acpi/scan.c
> > > > @@ -887,8 +887,12 @@ static int acpi_bus_get_power_flags(struct acpi_device *device)
> > > >  		/* Evaluate "_PSx" to see if we can do explicit sets */
> > > >  		object_name[2] = 'S';
> > > >  		status = acpi_get_handle(device->handle, object_name, &handle);
> > > > -		if (ACPI_SUCCESS(status))
> > > > +		if (ACPI_SUCCESS(status)) {
> > > >  			ps->flags.explicit_set = 1;
> > > > +			/* Also set D3Cold's explicit flag when _PS3 exists */
> > > > +			if (i == ACPI_STATE_D3_HOT)
> > > > +				(ps+1)->flags.explicit_set = 1;
> > > 
> > > Please don't use pointer arithmetics here.  I know it _happens_ to work,
> > > but I don't think it's appropriate in this situation at all.
> > > 
> > 
> > Thanks for the suggestions.
> > 
> > What about this?
> > 
> > diff --git a/drivers/acpi/bus.c b/drivers/acpi/bus.c
> > index 3263b68..3a7860f 100644
> > --- a/drivers/acpi/bus.c
> > +++ b/drivers/acpi/bus.c
> > @@ -273,6 +273,9 @@ static int __acpi_bus_set_power(struct acpi_device *device, int state)
> >  		}
> >  	} else {
> >  		if (device->power.states[state].flags.explicit_set) {
> > +			/* Evaluate _PS3 when entering D3cold */
> > +			if (state == ACPI_STATE_D3)
> > +				object_name[3] = '3';
> >  			status = acpi_evaluate_object(device->handle,
> >  						      object_name, NULL, NULL);
> >  			if (ACPI_FAILURE(status)) {
> > diff --git a/drivers/acpi/scan.c b/drivers/acpi/scan.c
> > index 7417267..734d946 100644
> > --- a/drivers/acpi/scan.c
> > +++ b/drivers/acpi/scan.c
> > @@ -908,6 +908,10 @@ static int acpi_bus_get_power_flags(struct acpi_device *device)
> >  	device->power.states[ACPI_STATE_D3].flags.valid = 1;
> >  	device->power.states[ACPI_STATE_D3].power = 0;
> >  
> > +	/* Also set D3cold's explicit flag when _PS3 exists */
> > +	if (device->power.states[ACPI_STATE_D3_HOT].flags.explicit_set)
> > +		device->power.states[ACPI_STATE_D3].flags.explicit_set = 1;
> 
> We should use ACPI_STATE_D3_COLD instead of ACPI_STATE_D3 to make thing
> clear.
>
Thanks for your suggestion.

Well, considering all those ACPI_STATE_D3 used in tree, I don't think I
should use ACPI_STATE_D3_COLD here, especially the two lines above are
still using ACPI_STATE_D3.

But if that is desired, we should probably change all the existing
ACPI_STATE_D3 macros to ACPI_STATE_D3_COLD to make things clear.

Or we all use ACPI_STATE_D3, since it is defined as 4 and means D3 cold,
and people will learn this, won't they?

What do you think?
 
Thanks,
Aaron

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