From: Bjorn Helgaas <helgaas@kernel.org>
To: linux-pci@vger.kernel.org
Cc: Lorenzo Pieralisi <lorenzo.pieralisi@arm.com>,
Keith Busch <keith.busch@intel.com>,
Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
"Rafael J . Wysocki" <rjw@rjwysocki.net>,
Mika Westerberg <mika.westerberg@linux.intel.com>,
linux-pm@vger.kernel.org, linux-kernel@vger.kernel.org,
Bjorn Helgaas <bhelgaas@google.com>
Subject: [PATCH 3/3] PCI / PM: Return error when changing power state from D3cold
Date: Thu, 22 Aug 2019 15:05:51 -0500 [thread overview]
Message-ID: <20190822200551.129039-4-helgaas@kernel.org> (raw)
In-Reply-To: <20190822200551.129039-1-helgaas@kernel.org>
From: Bjorn Helgaas <bhelgaas@google.com>
pci_raw_set_power_state() uses the Power Management capability to change a
device's power state. The capability is in config space, which is
accessible in D0, D1, D2, and D3hot, but not in D3cold.
If we call pci_raw_set_power_state() on a device that's in D3cold, config
reads fail and return ~0 data, which we erroneously interpreted as "the
device is in D3hot", leading to messages like this:
pcieport 0000:03:00.0: Refused to change power state, currently in D3
The PCI_PM_CTRL has several RsvdP fields, so ~0 is never a valid register
value. Notice if we get that data, print a more informative message, and
return an error.
Changing the power state of a device from D3cold must be done by a platform
power management method or some other non-config space mechanism.
Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>
---
drivers/pci/pci.c | 11 +++++++++--
1 file changed, 9 insertions(+), 2 deletions(-)
diff --git a/drivers/pci/pci.c b/drivers/pci/pci.c
index 5f0a3145c3f2..41112af189a8 100644
--- a/drivers/pci/pci.c
+++ b/drivers/pci/pci.c
@@ -853,6 +853,12 @@ static int pci_raw_set_power_state(struct pci_dev *dev, pci_power_t state)
return -EIO;
pci_read_config_word(dev, dev->pm_cap + PCI_PM_CTRL, &pmcsr);
+ if (pmcsr == (u16) PCI_ERROR_RESPONSE) {
+ pci_err(dev, "can't access config space to change power state from %s to %s\n",
+ pci_power_name(dev->current_state),
+ pci_power_name(state));
+ return -EIO;
+ }
/*
* If we're (effectively) in D3, force entire word to 0.
@@ -893,8 +899,9 @@ static int pci_raw_set_power_state(struct pci_dev *dev, pci_power_t state)
pci_read_config_word(dev, dev->pm_cap + PCI_PM_CTRL, &pmcsr);
dev->current_state = (pmcsr & PCI_PM_CTRL_STATE_MASK);
if (dev->current_state != state && printk_ratelimit())
- pci_info(dev, "refused to change power state (currently %s)\n",
- pci_power_name(dev->current_state));
+ pci_info(dev, "refused to change power state from %s to %s\n",
+ pci_power_name(dev->current_state),
+ pci_power_name(state));
/*
* According to section 5.4.1 of the "PCI BUS POWER MANAGEMENT
--
2.23.0.187.g17f5b7556c-goog
next prev parent reply other threads:[~2019-08-22 20:06 UTC|newest]
Thread overview: 10+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-08-22 20:05 [PATCH v2 0/3] PCI: Add PCI_ERROR_RESPONSE, check for errors Bjorn Helgaas
2019-08-22 20:05 ` [PATCH 1/3] PCI: Add PCI_ERROR_RESPONSE definition Bjorn Helgaas
2019-08-23 10:44 ` Andrew Murray
2019-08-23 19:29 ` Bjorn Helgaas
2019-08-22 20:05 ` [PATCH 2/3] PCI / PM: Decode D3cold power state correctly Bjorn Helgaas
2019-08-22 20:05 ` Bjorn Helgaas [this message]
2019-08-22 21:10 ` [PATCH 3/3] PCI / PM: Return error when changing power state from D3cold Rafael J. Wysocki
2019-08-23 7:22 ` [PATCH v2 0/3] PCI: Add PCI_ERROR_RESPONSE, check for errors Mika Westerberg
2019-08-23 15:04 ` Keith Busch
2019-11-14 20:19 ` Bjorn Helgaas
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