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[217.229.167.59]) by smtp.gmail.com with ESMTPSA id c11sm2120481eds.62.2020.11.02.06.15.34 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Mon, 02 Nov 2020 06:15:35 -0800 (PST) From: Maximilian Luz To: Bjorn Helgaas Cc: Heiner Kallweit , linux-pci@vger.kernel.org, linux-kernel@vger.kernel.org, Maximilian Luz Subject: [PATCH] PCI: Add sysfs attribute for PCI device power state Date: Mon, 2 Nov 2020 15:15:20 +0100 Message-Id: <20201102141520.831630-1-luzmaximilian@gmail.com> X-Mailer: git-send-email 2.29.2 MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: linux-pci@vger.kernel.org While most PCI power-states can be queried from user-space via lspci, this has some limits. Specifically, lspci fails to provide an accurate value when the device is in D3cold as it has to resume the device before it can access its power state via the configuration space, leading to it reporting D0 or another on-state. Thus lspci can, for example, not be used to diagnose power-consumption issues for devices that can enter D3cold or to ensure that devices properly enter D3cold at all. To alleviate this issue, introduce a new sysfs device attribute for the PCI power state, showing the current power state as seen by the kernel. Signed-off-by: Maximilian Luz --- Documentation/ABI/testing/sysfs-bus-pci | 9 +++++++++ drivers/pci/pci-sysfs.c | 12 ++++++++++++ 2 files changed, 21 insertions(+) diff --git a/Documentation/ABI/testing/sysfs-bus-pci b/Documentation/ABI/testing/sysfs-bus-pci index 450296cc7948..881040af2611 100644 --- a/Documentation/ABI/testing/sysfs-bus-pci +++ b/Documentation/ABI/testing/sysfs-bus-pci @@ -360,3 +360,12 @@ Contact: Heiner Kallweit Description: If ASPM is supported for an endpoint, these files can be used to disable or enable the individual power management states. Write y/1/on to enable, n/0/off to disable. + +What: /sys/bus/pci/devices/.../power_state +Date: November 2020 +Contact: Linux PCI developers +Description: + This file contains the current PCI power state of the device. + The value comes from the PCI kernel device state and can be one + of: "unknown", "error", "D0", D1", "D2", "D3hot", "D3cold". + The file is read only. diff --git a/drivers/pci/pci-sysfs.c b/drivers/pci/pci-sysfs.c index d15c881e2e7e..b15f754e6346 100644 --- a/drivers/pci/pci-sysfs.c +++ b/drivers/pci/pci-sysfs.c @@ -124,6 +124,17 @@ static ssize_t cpulistaffinity_show(struct device *dev, } static DEVICE_ATTR_RO(cpulistaffinity); +/* PCI power state */ +static ssize_t power_state_show(struct device *dev, + struct device_attribute *attr, char *buf) +{ + struct pci_dev *pci_dev = to_pci_dev(dev); + pci_power_t state = READ_ONCE(pci_dev->current_state); + + return sprintf(buf, "%s\n", pci_power_name(state)); +} +static DEVICE_ATTR_RO(power_state); + /* show resources */ static ssize_t resource_show(struct device *dev, struct device_attribute *attr, char *buf) @@ -581,6 +592,7 @@ static ssize_t driver_override_show(struct device *dev, static DEVICE_ATTR_RW(driver_override); static struct attribute *pci_dev_attrs[] = { + &dev_attr_power_state.attr, &dev_attr_resource.attr, &dev_attr_vendor.attr, &dev_attr_device.attr, -- 2.29.2