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authorEmil Velikov <emil.velikov@collabora.com>2016-11-21 16:24:49 -0600
committerBjorn Helgaas <bhelgaas@google.com>2016-11-21 16:25:32 -0600
commit702ed3be1b1bf4dea05954168321741c0910c645 (patch)
tree4148dde5865bb993433dbf80be09d7a26b2121ca
parent1001354ca34179f3db924eb66672442a173147dc (diff)
PCI: Create revision file in sysfs
Currently the revision isn't available via sysfs/libudev thus if one wants to know the value one needs to read through the config file, which can be quite time-consuming because it wakes/powers up the device. There are at least two userspace components which could make use the new file: libpciaccess and libdrm. The former wakes up _every_ PCI device, which can be observed via glxinfo when using Mesa 10.0+ drivers. The latter, in association with Mesa 13.0, can lead to 2-3 second delays while starting firefox, thunderbird or chromium. Link: https://bugs.freedesktop.org/show_bug.cgi?id=98502 Tested-by: Mauro Santos <registo.mailling@gmail.com> Signed-off-by: Emil Velikov <emil.velikov@collabora.com> Signed-off-by: Bjorn Helgaas <bhelgaas@google.com> Reviewed-by: Alex Deucher <alexander.deucher@amd.com> Reviewed-by: Daniel Vetter <daniel.vetter@ffwll.ch CC: Greg KH <gregkh@linuxfoundation.org>
-rw-r--r--Documentation/ABI/testing/sysfs-bus-pci7
-rw-r--r--Documentation/filesystems/sysfs-pci.txt2
-rw-r--r--drivers/pci/pci-sysfs.c2
3 files changed, 11 insertions, 0 deletions
diff --git a/Documentation/ABI/testing/sysfs-bus-pci b/Documentation/ABI/testing/sysfs-bus-pci
index b3bc50f..5a1732b 100644
--- a/Documentation/ABI/testing/sysfs-bus-pci
+++ b/Documentation/ABI/testing/sysfs-bus-pci
@@ -294,3 +294,10 @@ Description:
a firmware bug to the system vendor. Writing to this file
taints the kernel with TAINT_FIRMWARE_WORKAROUND, which
reduces the supportability of your system.
+
+What: /sys/bus/pci/devices/.../revision
+Date: November 2016
+Contact: Emil Velikov <emil.l.velikov@gmail.com>
+Description:
+ This file contains the revision field of the the PCI device.
+ The value comes from device config space. The file is read only.
diff --git a/Documentation/filesystems/sysfs-pci.txt b/Documentation/filesystems/sysfs-pci.txt
index 74eaac2..6ea1ced 100644
--- a/Documentation/filesystems/sysfs-pci.txt
+++ b/Documentation/filesystems/sysfs-pci.txt
@@ -17,6 +17,7 @@ that support it. For example, a given bus might look like this:
| |-- resource0
| |-- resource1
| |-- resource2
+ | |-- revision
| |-- rom
| |-- subsystem_device
| |-- subsystem_vendor
@@ -41,6 +42,7 @@ files, each with their own function.
resource PCI resource host addresses (ascii, ro)
resource0..N PCI resource N, if present (binary, mmap, rw[1])
resource0_wc..N_wc PCI WC map resource N, if prefetchable (binary, mmap)
+ revision PCI revision (ascii, ro)
rom PCI ROM resource, if present (binary, ro)
subsystem_device PCI subsystem device (ascii, ro)
subsystem_vendor PCI subsystem vendor (ascii, ro)
diff --git a/drivers/pci/pci-sysfs.c b/drivers/pci/pci-sysfs.c
index bcd10c7..0666287 100644
--- a/drivers/pci/pci-sysfs.c
+++ b/drivers/pci/pci-sysfs.c
@@ -50,6 +50,7 @@ pci_config_attr(vendor, "0x%04x\n");
pci_config_attr(device, "0x%04x\n");
pci_config_attr(subsystem_vendor, "0x%04x\n");
pci_config_attr(subsystem_device, "0x%04x\n");
+pci_config_attr(revision, "0x%02x\n");
pci_config_attr(class, "0x%06x\n");
pci_config_attr(irq, "%u\n");
@@ -568,6 +569,7 @@ static struct attribute *pci_dev_attrs[] = {
&dev_attr_device.attr,
&dev_attr_subsystem_vendor.attr,
&dev_attr_subsystem_device.attr,
+ &dev_attr_revision.attr,
&dev_attr_class.attr,
&dev_attr_irq.attr,
&dev_attr_local_cpus.attr,