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 09:18:50 -0700
From:   Srinivas Pandruvada <srinivas.pandruvada@...ux.intel.com>
To:     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 Fri, 2017-08-11 at 14:43 +0000, Mario.Limonciello@...l.com wrote:
> > 
> > -----Original Message-----
> > From: Srinivas Pandruvada [mailto:srinivas.pandruvada@...ux.intel.c
> > om]
> > 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?
There is no _PSC for XHC device. So it will return unknown. This is an
optional object, so I think that dumping the status is fine, but
matching with output of acpi_device_get_power() as it relies on _PSC is
not correct for the constraint.

Thanks,
Srinivas

> 
> > 
> > > 
> > > 
> > > > 
> > > > 
> > > > +
> > > > +		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_ir
> > > > q)))
> > > > {
> > > > +		if (pm_debug_messages_enabled())
> > > > +			lpi_check_constraints();
> > > >  		pm_system_cancel_wakeup();
> > > >  		s2idle_wakeup = true;
> > > >  	}
> > > > --
> > > > 2.7.5