diff options
Diffstat (limited to 'doc/driver-model')
| -rw-r--r-- | doc/driver-model/pci-info.txt | 14 |
1 files changed, 9 insertions, 5 deletions
diff --git a/doc/driver-model/pci-info.txt b/doc/driver-model/pci-info.txt index e1701d1fbc..14364c5c75 100644 --- a/doc/driver-model/pci-info.txt +++ b/doc/driver-model/pci-info.txt @@ -34,11 +34,15 @@ under that bus. Note that this is all done on a lazy basis, as needed, so until something is touched on PCI (eg: a call to pci_find_devices()) it will not be probed. -PCI devices can appear in the flattened device tree. If they do this serves to -specify the driver to use for the device. In this case they will be bound at -first. Each PCI device node must have a compatible string list as well as a -<reg> property, as defined by the IEEE Std 1275-1994 PCI bus binding document -v2.1. Note we must describe PCI devices with the same bus hierarchy as the +PCI devices can appear in the flattened device tree. If they do, their node +often contains extra information which cannot be derived from the PCI IDs or +PCI class of the device. Each PCI device node must have a <reg> property, as +defined by the IEEE Std 1275-1994 PCI bus binding document v2.1. Compatible +string list is optional and generally not needed, since PCI is discoverable +bus, albeit there are justified exceptions. If the compatible string is +present, matching on it takes precedence over PCI IDs and PCI classes. + +Note we must describe PCI devices with the same bus hierarchy as the hardware, otherwise driver model cannot detect the correct parent/children relationship during PCI bus enumeration thus PCI devices won't be bound to their drivers accordingly. A working example like below: |