Hi Marex, On 11 September 2018 at 14:58, Marek Vasut <marek.va...@gmail.com> wrote: > Reword the documentation to make it clear the compatible string is now > optional, yet still matching on it takes precedence over PCI IDs and > PCI classes. > > Signed-off-by: Marek Vasut <marek.vasut+rene...@gmail.com> > Cc: Simon Glass <s...@chromium.org> > Cc: Tom Rini <tr...@konsulko.com> > --- > V3: No change > V2: New patch > --- > doc/driver-model/pci-info.txt | 14 +++++++++----- > 1 file 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
I really don't like 'generally not needed'. How about 'generally not essential'? Or that you can usually avoid it if desired. I'd like to say that it is optional since U_BOOT_PCI_DEVICE() can be used to specific the driver based on conditions like the PCI vendor/, PCI class, etc. If U-Boot does not find a compatible string then it will search these U_BOOT_PCI_DEVICE() records to find a driver; assuming it finds one it will then search for the device-tree node whose reg property matches the bus/device/function of the device, and attached that node to the device so that it is accessible to the driver. > +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: > -- > 2.18.0 > Regards, Simon _______________________________________________ U-Boot mailing list U-Boot@lists.denx.de https://lists.denx.de/listinfo/u-boot
