linux-kernel - RE: [PATCH v2 2/2] ACPI / Sleep: Check low power idle constraints for debug only

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Date:   Fri, 11 Aug 2017 14:43:25 +0000
From:   <Mario.Limonciello@...l.com>
To:     <srinivas.pandruvada@...ux.intel.com>, <rjw@...ysocki.net>,
        <lenb@...nel.org>
CC:     <linux-pm@...r.kernel.org>, <linux-kernel@...r.kernel.org>,
        <linux-acpi@...r.kernel.org>, <lukas@...ner.de>
Subject: RE: [PATCH v2 2/2] ACPI / Sleep: Check low power idle constraints for
 debug only

> -----Original Message-----
> From: Srinivas Pandruvada [mailto:srinivas.pandruvada@...ux.intel.com]
> Sent: Thursday, August 10, 2017 5:54 PM
> To: Limonciello, Mario <Mario_Limonciello@...l.com>; rjw@...ysocki.net;
> lenb@...nel.org
> Cc: linux-pm@...r.kernel.org; linux-kernel@...r.kernel.org; linux-
> acpi@...r.kernel.org; lukas@...ner.de
> Subject: Re: [PATCH v2 2/2] ACPI / Sleep: Check low power idle constraints for
> debug only
> 
> On Thu, 2017-08-10 at 22:07 +0000, Mario.Limonciello@...l.com wrote:
> >
> > >
> > >
> [...]
> 
> > > +
> > > +		ret = acpi_device_get_power(adev, &state);
> > > +		if (!ret)
> > > +			pr_debug("LPI: %s required min power state
> > > %d, current
> > > power state %d, real power state %d\n",
> > > +				 lpi_constraints_table[i].name,
> > > +				 lpi_constraints_table[i].min_dsta
> > > te,
> > > +				 adev->power.state, state);
> > Isn't this superfluous to be showing the state returned from
> > acpi_device_get_power and
> > also probing directly at the state? You can't just rely on the
> > information you got
> > back from apci_device_get_power?
> They can be different as one is real power state and the other is what
> was set.
> For example on Dell 9365 it shows
> 
> [ 1924.393653] LPI: \_SB.PCI0.XHC required min power state 3, current
> power state 3, real power state 255
> 

Isn't 255 ACPI_STATE_UNKNOWN?  That makes it seem like it
is a logic problem in acpi_device_get_power (or somewhere down the chain)
doesn't it?

> >
> > >
> > > +
> > > +		if (adev->flags.power_manageable && adev-
> > > >power.state <
> > > +					lpi_constraints_table[i].m
> > > in_dstate)
> > > +			pr_info("LPI: Constraint [%s] not
> > > matched\n",
> > > +				 lpi_constraints_table[i].name);
> > Similarly here, can't you just compare against &state instead?
> >
> The problem then the check will fail for XHCI on Dell 9365. So not
> using "state".
> 
> Thanks,
> Srinivas
> > >
> > > +	}
> > > +}
> > > +
> > >  static void acpi_sleep_run_lps0_dsm(unsigned int func)
> > >  {
> > >  	union acpi_object *out_obj;
> > > @@ -729,6 +886,9 @@ static int lps0_device_attach(struct
> > > acpi_device *adev,
> > >  				  "_DSM function 0 evaluation
> > > failed\n");
> > >  	}
> > >  	ACPI_FREE(out_obj);
> > > +
> > > +	lpi_device_get_constraints();
> > > +
> > >  	return 0;
> > >  }
> > >
> > > @@ -773,6 +933,8 @@ static void acpi_freeze_wake(void)
> > >  	 */
> > >  	if (acpi_sci_irq_valid() &&
> > >  	    !irqd_is_wakeup_armed(irq_get_irq_data(acpi_sci_irq)))
> > > {
> > > +		if (pm_debug_messages_enabled())
> > > +			lpi_check_constraints();
> > >  		pm_system_cancel_wakeup();
> > >  		s2idle_wakeup = true;
> > >  	}
> > > --
> > > 2.7.5