On Friday 28 March 2014 16:21:38 Liviu Dudau wrote: > On Fri, Mar 28, 2014 at 03:20:20PM +0000, Rob Herring wrote: > > On Fri, Mar 28, 2014 at 9:57 AM, Liviu Dudau <Liviu.Dudau@xxxxxxx> wrote: > > > PCI core? It knows nothing of the Versatile registers. Versatile core code? Maybe. > > > > These are all standard config space registers based on the offsets and > > documentation. The only thing that I think might make this Versatile > > specific is a host bridge having its own config space at all is > > optional. > > Sorry, got confused by your CSR_OFFSET macro into thinking it's Versatile specific (I > still cannot get hold of the SP810 manual, sigh). Why don't you use PCI_COMMAND ? While it's not uncommon to have PCI host controllers use a similar layout for their own registers as the normal config space, I believe this is not standardized anywhere. It may be better not to pretend that this is a standard register. > For PCIe the spec is a bit more forgiving is you use ECAM, although it doesn't > explicitly allow writes to the config space of the host bridge. From PCI Express > Base spec, rev 3.0: > > 7.2.2.1. Host Bridge Requirements > For those systems that implement the ECAM, the PCI Express Host Bridge is > required to translate the memory-mapped PCI Express Configuration Space > accesses from the host processor to PCI Express configuration transactions. > The use of Host Bridge PCI class code is Reserved for backwards compatibility; > host Bridge Configuration Space is opaque to standard PCI Express software > and may be implemented in an implementation specific manner that is compatible > with PCI Host Bridge Type 0 Configuration Space. A PCI Express Host Bridge is > not required to signal errors through a Root Complex Event Collector. This > support is optional for PCI Express Host Bridges. > > So it looks like you need to do those in the host bridge probe function, rather than > in a generic way. Right. FWIW, the reason why these have a normal register layout seems to be that the same hardware is used for host controller and endpoint devices. Arnd -- To unsubscribe from this list: send the line "unsubscribe linux-pci" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
