|
[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index] Re: [Xen-devel] [PATCH v4 6/6] xen: arm: Import of_bus PCI entry from Linux (as a dt_bus entry)
On 03/07/15 11:56, Ian Campbell wrote: > On Fri, 2015-07-03 at 11:47 +0100, Ian Campbell wrote: >> On Fri, 2015-06-26 at 20:08 +0200, Julien Grall wrote: >>> Hi Ian, >>> >>> On 08/05/2015 13:27, Ian Campbell wrote: >>>> This provides specific handlers for the PCI bus relating to matching >>>> and translating. It's mostly similar to the defaults but includes some >>>> additional error checks and other PCI specific bits. >>> >>> I though the previous patch (#5) was enough to handle PCI. May I ask why >>> we need it? >> >> There are some subtle differences in how the generic code vs. the pci >> specific code here will handle buggy DTs (i.e. #*-cells which are not as >> required by the pci bindings). This will mean we tolerate such device >> trees better. >> >> I say "buggy", but actually it's not clear to me from reading "PCI Bus >> Binding to Open Firmware" that when the device_type is "pci" that >> #*-cells shouldn't be assumed to have the values given in that text, >> e.g. the text says "The value of "#address-cells" for PCI Bus Nodes is >> 3." and not "A PCI Bus Node must contain a #address-cells property >> containing 3". Maybe that interpretation is bogus, but with this patch >> we are are able to cope with DTs written by people who do read it like >> that. If the #address-cells and #size-cells are not correct that will likely means that the property "reg" in the PCI node would be misinterpreted by Xen. I think it's here to cope with DT when #*-cells are not specified. The spec doesn't say if the properties should be present or not. >> FWIW it also gets us the ability to parse the flags (cacheability), >> although at the moment we only check them for validity rather than use >> them. Good point. > I've pasted a slightly adjusted version of this into the commit message > for v5. Thank you! Regards, -- Julien Grall _______________________________________________ Xen-devel mailing list Xen-devel@xxxxxxxxxxxxx http://lists.xen.org/xen-devel
|
 |
Lists.xenproject.org is hosted with RackSpace, monitoring our |