From: Kai-Heng Feng <kai.heng.feng@canonical.com>
To: "Rafael J. Wysocki" <rjw@rjwysocki.net>
Cc: Linux ACPI <linux-acpi@vger.kernel.org>,
Linux PM <linux-pm@vger.kernel.org>,
Linux PCI <linux-pci@vger.kernel.org>,
LKML <linux-kernel@vger.kernel.org>,
Mika Westerberg <mika.westerberg@linux.intel.com>,
Bjorn Helgaas <helgaas@kernel.org>,
Mario Limonciello <mario.limonciello@dell.com>
Subject: Re: [PATCH] ACPI: PM: Fix regression in acpi_device_set_power()
Date: Thu, 1 Aug 2019 14:11:00 +0800 [thread overview]
Message-ID: <27715F95-E729-4EF5-B2BA-03BA3C87AE29@canonical.com> (raw)
In-Reply-To: <4199592.UtrPOv3ZmA@kreacher>
at 07:31, Rafael J. Wysocki <rjw@rjwysocki.net> wrote:
> From: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
>
> Commit f850a48a0799 ("ACPI: PM: Allow transitions to D0 to occur in
> special cases") overlooked the fact that acpi_power_transition() may
> change the power.state value for the target device and if that
> happens, it may confuse acpi_device_set_power() and cause it to
> omit the _PS0 evaluation which on some systems is necessary to
> change power states of devices from low-power to D0.
>
> Fix that by saving the current value of power.state for the
> target device before passing it to acpi_power_transition() and
> using the saved value in a subsequent check.
>
> Fixes: f850a48a0799 ("ACPI: PM: Allow transitions to D0 to occur in
> special cases")
> Reported-by: Kai-Heng Feng <kai.heng.feng@canonical.com>
> Reported-by: Mario Limonciello <mario.limonciello@dell.com>
> Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Tested-by: Kai-Heng Feng <kai.heng.feng@canonical.com>
> ---
> drivers/acpi/device_pm.c | 4 +++-
> 1 file changed, 3 insertions(+), 1 deletion(-)
>
> Index: linux-pm/drivers/acpi/device_pm.c
> ===================================================================
> --- linux-pm.orig/drivers/acpi/device_pm.c
> +++ linux-pm/drivers/acpi/device_pm.c
> @@ -236,13 +236,15 @@ int acpi_device_set_power(struct acpi_de
> if (device->power.flags.power_resources)
> result = acpi_power_transition(device, target_state);
> } else {
> + int cur_state = device->power.state;
> +
> if (device->power.flags.power_resources) {
> result = acpi_power_transition(device, ACPI_STATE_D0);
> if (result)
> goto end;
> }
>
> - if (device->power.state == ACPI_STATE_D0) {
> + if (cur_state == ACPI_STATE_D0) {
> int psc;
>
> /* Nothing to do here if _PSC is not present. */
next prev parent reply other threads:[~2019-08-01 6:11 UTC|newest]
Thread overview: 3+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-07-31 23:31 [PATCH] ACPI: PM: Fix regression in acpi_device_set_power() Rafael J. Wysocki
2019-08-01 6:11 ` Kai-Heng Feng [this message]
2019-08-01 19:06 ` Mario.Limonciello
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