From: "Rafael J. Wysocki" <rjw@rjwysocki.net>
To: Linux PCI <linux-pci@vger.kernel.org>
Cc: Linux PM <linux-pm@vger.kernel.org>,
Linux ACPI <linux-acpi@vger.kernel.org>,
LKML <linux-kernel@vger.kernel.org>,
Bjorn Helgaas <helgaas@kernel.org>,
Mika Westerberg <mika.westerberg@linux.intel.com>,
Keith Busch <kbusch@kernel.org>,
Kai-Heng Feng <kai.heng.feng@canonical.com>
Subject: [PATCH] PCI: PM: Skip devices in D0 for suspend-to-idle
Date: Thu, 13 Jun 2019 00:14:02 +0200 [thread overview]
Message-ID: <2513600.jR9RdVMSR0@kreacher> (raw)
From: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Commit d491f2b75237 ("PCI: PM: Avoid possible suspend-to-idle issue")
attempted to avoid a problem with devices whose drivers want them to
stay in D0 over suspend-to-idle and resume, but it did not go as far
as it should with that.
Namely, first of all, it is questionable to change the power state
of a PCI bridge with a device in D0 under it, but that is not
actively prevented from happening during system-wide PM transitions,
so use the skip_bus_pm flag introduced by commit d491f2b75237 for
that.
Second, the configuration of devices left in D0 (whatever the reason)
during suspend-to-idle need not be changed and attempting to put them
into D0 again by force may confuse some firmware, so explicitly avoid
doing that.
Fixes: d491f2b75237 ("PCI: PM: Avoid possible suspend-to-idle issue")
Reported-by: Kai-Heng Feng <kai.heng.feng@canonical.com>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
---
Tested on Dell XPS13 9360 with no issues.
---
drivers/pci/pci-driver.c | 47 +++++++++++++++++++++++++++++++++++------------
1 file changed, 35 insertions(+), 12 deletions(-)
Index: linux-pm/drivers/pci/pci-driver.c
===================================================================
--- linux-pm.orig/drivers/pci/pci-driver.c
+++ linux-pm/drivers/pci/pci-driver.c
@@ -524,7 +524,6 @@ static void pci_pm_default_resume_early(
pci_power_up(pci_dev);
pci_restore_state(pci_dev);
pci_pme_restore(pci_dev);
- pci_fixup_device(pci_fixup_resume_early, pci_dev);
}
/*
@@ -842,18 +841,16 @@ static int pci_pm_suspend_noirq(struct d
if (pci_dev->skip_bus_pm) {
/*
- * The function is running for the second time in a row without
+ * Either the device is a bridge with a child in D0 below it, or
+ * the function is running for the second time in a row without
* going through full resume, which is possible only during
- * suspend-to-idle in a spurious wakeup case. Moreover, the
- * device was originally left in D0, so its power state should
- * not be changed here and the device register values saved
- * originally should be restored on resume again.
+ * suspend-to-idle in a spurious wakeup case. The device should
+ * be in D0 at this point, but if it is a bridge, it may be
+ * necessary to save its state.
*/
- pci_dev->state_saved = true;
- } else if (pci_dev->state_saved) {
- if (pci_dev->current_state == PCI_D0)
- pci_dev->skip_bus_pm = true;
- } else {
+ if (!pci_dev->state_saved)
+ pci_save_state(pci_dev);
+ } else if (!pci_dev->state_saved) {
pci_save_state(pci_dev);
if (pci_power_manageable(pci_dev))
pci_prepare_to_sleep(pci_dev);
@@ -862,6 +859,22 @@ static int pci_pm_suspend_noirq(struct d
dev_dbg(dev, "PCI PM: Suspend power state: %s\n",
pci_power_name(pci_dev->current_state));
+ if (pci_dev->current_state == PCI_D0) {
+ pci_dev->skip_bus_pm = true;
+ /*
+ * Changing the power state of a PCI bridge with a device in D0
+ * below it is questionable, so avoid doing that by setting the
+ * skip_bus_pm flag for the parent bridge.
+ */
+ if (pci_dev->bus->self)
+ pci_dev->bus->self->skip_bus_pm = true;
+ }
+
+ if (pci_dev->skip_bus_pm && !pm_suspend_via_firmware()) {
+ dev_dbg(dev, "PCI PM: Skipped\n");
+ goto Fixup;
+ }
+
pci_pm_set_unknown_state(pci_dev);
/*
@@ -909,7 +922,16 @@ static int pci_pm_resume_noirq(struct de
if (dev_pm_smart_suspend_and_suspended(dev))
pm_runtime_set_active(dev);
- pci_pm_default_resume_early(pci_dev);
+ /*
+ * In the suspend-to-idle case, devices left in D0 during suspend will
+ * stay in D0, so it is not necessary to restore or update their
+ * configuration here and attempting to put them into D0 again may
+ * confuse some firmware, so avoid doing that.
+ */
+ if (!pci_dev->skip_bus_pm || pm_suspend_via_firmware())
+ pci_pm_default_resume_early(pci_dev);
+
+ pci_fixup_device(pci_fixup_resume_early, pci_dev);
if (pci_has_legacy_pm_support(pci_dev))
return pci_legacy_resume_early(dev);
@@ -1200,6 +1222,7 @@ static int pci_pm_restore_noirq(struct d
}
pci_pm_default_resume_early(pci_dev);
+ pci_fixup_device(pci_fixup_resume_early, pci_dev);
if (pci_has_legacy_pm_support(pci_dev))
return pci_legacy_resume_early(dev);
next reply other threads:[~2019-06-13 17:12 UTC|newest]
Thread overview: 6+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-06-12 22:14 Rafael J. Wysocki [this message]
2019-06-13 6:13 ` [PATCH] PCI: PM: Skip devices in D0 for suspend-to-idle Kai-Heng Feng
2019-06-13 12:57 ` Mika Westerberg
2019-06-13 18:49 ` Rafael J. Wysocki
2019-06-13 21:38 ` Bjorn Helgaas
2019-06-13 21:46 ` Rafael J. Wysocki
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=2513600.jR9RdVMSR0@kreacher \
--to=rjw@rjwysocki.net \
--cc=helgaas@kernel.org \
--cc=kai.heng.feng@canonical.com \
--cc=kbusch@kernel.org \
--cc=linux-acpi@vger.kernel.org \
--cc=linux-kernel@vger.kernel.org \
--cc=linux-pci@vger.kernel.org \
--cc=linux-pm@vger.kernel.org \
--cc=mika.westerberg@linux.intel.com \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).