linux-kernel - Re: [PATCH] ACPI / PCI / PM: Fix device PM regression related to D3hot/D3cold

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Date:	Fri, 18 May 2012 01:56:30 -0400
From:	Cristian Rodríguez <crrodriguez@...nsuse.org>
To:	"Rafael J. Wysocki" <rjw@...k.pl>
CC:	Linus Torvalds <torvalds@...ux-foundation.org>,
	Len Brown <lenb@...nel.org>, Lekensteyn <lekensteyn@...il.com>,
	LKML <linux-kernel@...r.kernel.org>,
	Linux PM list <linux-pm@...r.kernel.org>,
	ACPI Devel Mailing List <linux-acpi@...r.kernel.org>,
	Lin Ming <ming.m.lin@...el.com>,
	rocko <rockorequin@...mail.com>
Subject: Re: [PATCH] ACPI / PCI / PM: Fix device PM regression related to
 D3hot/D3cold

On 17/05/12 18:39, Rafael J. Wysocki wrote:
> From: Rafael J. Wysocki<rjw@...k.pl>
>
> Commit 1cc0c998fdf2cb665d625fb565a0d6db5c81c639 (ACPI: Fix D3hot
> v D3cold confusion) introduced a bug in __acpi_bus_set_power() and
> changed the behavior of acpi_pci_set_power_state() in such a way that
> it generally doesn't work as expected if PCI_D3hot is passed to it
> as the second argument.
>
> First off, if ACPI_STATE_D3 (equal to ACPI_STATE_D3_COLD) is passed
> to __acpi_bus_set_power() and the explicit_set flag is set for the
> D3cold state, the function will try to execute AML method called
> "_PS4", which doesn't exist.
>
> Fix this by adding a check to ensure that the name of the AML method
> to execute for transitions to ACPI_STATE_D3_COLD is correct in
> __acpi_bus_set_power().  Also make sure that the explicit_set flag
> for ACPI_STATE_D3_COLD will be set if _PS3 is present and modify
> acpi_power_transition() to avoid accessing power resources for
> ACPI_STATE_D3_COLD, because they don't exist.
>
> Second, if PCI_D3hot is passed to acpi_pci_set_power_state() as the
> target state, the function will request a transition to
> ACPI_STATE_D3_HOT instead of ACPI_STATE_D3.  However,
> ACPI_STATE_D3_HOT is now only marked as supported if the _PR3 AML
> method is defined for the given device, which is rare.  This causes
> problems to happen on systems where devices were successfully put
> into ACPI D3 by pci_set_power_state(PCI_D3hot) which doesn't work
> now.  In particular, some unused graphics adapters are not turned
> off as a result.
>
> To fix this issue restore the old behavior of
> acpi_pci_set_power_state(), which is to request a transition to
> ACPI_STATE_D3 (equal to ACPI_STATE_D3_COLD) if either PCI_D3hot or
> PCI_D3cold is passed to it as the argument.
>
> This approach is not ideal, because generally power should not
> be removed from devices if PCI_D3hot is the target power state,
> but since this behavior is relied on, we have no choice but to
> restore it at the moment and spend more time on designing a
> better solution in the future.
>
> References: https://bugzilla.kernel.org/show_bug.cgi?id=43228
> Reported-by: rocko<rockorequin@...mail.com>
> Reported-by: Cristian Rodríguez<crrodriguez@...nsuse.org>
> Reported-and-tested-by: Peter<lekensteyn@...il.com>
> Signed-off-by: Rafael J. Wysocki<rjw@...k.pl>
> ---

Ok, tested this one in the affected box, it works.

echo OFF > /sys/kernel/debug/vgaswitcheroo/switch
[   77.436767] VGA switcheroo: switched nouveau off
[   77.437004] [drm] nouveau 0000:01:00.0: Disabling display...
[   77.437110] [drm] nouveau 0000:01:00.0: Disabling fbcon...
[   77.437113] [drm] nouveau 0000:01:00.0: Unpinning framebuffer(s)...
[   77.437157] [drm] nouveau 0000:01:00.0: Evicting buffers...
[   77.439175] [drm] nouveau 0000:01:00.0: Idling channels...
[   77.439316] [drm] nouveau 0000:01:00.0: Suspending GPU objects...
[   77.771133] [drm] nouveau 0000:01:00.0: And we're gone!
[   78.082258] nouveau 0000:01:00.0: power state changed by ACPI to D3

laptop's fan is silent again :-) , thanks for fixing it !



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