On Wednesday 19 February 2014 11:07:19 Will Deacon wrote: > On Tue, Feb 18, 2014 at 07:10:23PM +0000, Will Deacon wrote: > > On Tue, Feb 18, 2014 at 01:46:44PM +0000, Arnd Bergmann wrote: > > > On Tuesday 18 February 2014 12:20:43 Will Deacon wrote: > > > > + /* Register our I/O and Memory resources */ > > > > + res_valid = 0; > > > > + list_for_each_entry(win, &pci->host.windows, list) { > > > > + struct resource *parent; > > > > + > > > > + if (resource_type(win->res) == IORESOURCE_IO) { > > > > + parent = &ioport_resource; > > > > + err = pci_ioremap_io(win->offset, win->res->start); > > > > > > and consequently pass the pci_addr rather than the offset here. How about > > > moving the pci_ioremap_io() call into gen_pci_alloc_io_offset()? > > I've probably just confused myself, but passing the pci_addr to > pci_ioremap_io doesn't make sense to me. I think the confusion is that there are two different things we call offset here. The calculation of the offset you pass into pci_ioremap_io() is correct AFAICT now, but it's not what you are supposed to pass into pci_add_resource_offset() or what we normally put into pci_host_bridge_window->offset. > My understanding is that: > > cpu = bus + offset Right. This would be the case for mem_offset. > In the case of I/O, the offset is really: > > offset = (PCI_IO_VIRT_BASE - bus) + window I can't seem to make sense of this calculation. PCI_IO_VIRT_BASE is a pointer to the start of the virtual window. You can add offsets to the pointer, but subtracting a number from it is not a well-defined operation. > where window is determined by the simple allocator I wrote. And your allocator calls it offset, which is what confused me. > Now, the __io macro takes care of PCI_IO_VIRT_BASE so we don't actually care > about that when adding the PCI I/O resources, instead we'll just pass: > > offset = window - bus Yes, this would be the io_offset that you pass into pci_add_resource_offset(). > and then pci_ioremap_io will just want the window offset, since that's added > directly on to PCI_IO_VIRT_BASE for the ioremap_page_range. Yes. > If I call pci_ioremap_io(range->pci_addr, ...) then I'm going to trip a BUG_ON > unless the pci_addr is within IO_SPACE_LIMIT. range->pci_addr is what you call 'bus' above. Since you want 'window', you have to pass 'bus'+'offset', or 'range->pci_addr + io_offset'. Normally, one of the two would be zero, while the other is equal to 'window'. 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