Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752441AbbGNREN (ORCPT ); Tue, 14 Jul 2015 13:04:13 -0400 Received: from foss.arm.com ([217.140.101.70]:35137 "EHLO foss.arm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751968AbbGNREM (ORCPT ); Tue, 14 Jul 2015 13:04:12 -0400 Date: Tue, 14 Jul 2015 18:04:08 +0100 From: Will Deacon To: David Daney Cc: David Daney , "linux-arm-kernel@lists.infradead.org" , Catalin Marinas , "linux-kernel@vger.kernel.org" , Robert Richter , David Daney Subject: Re: [PATCH] arm64: Define HAVE_ARCH_PIO_SIZE and related symbols. Message-ID: <20150714170408.GS16213@arm.com> References: <1436823096-24059-1-git-send-email-ddaney.cavm@gmail.com> <20150714110039.GC16213@arm.com> <55A53509.4060202@caviumnetworks.com> <20150714162955.GR16213@arm.com> <55A53FAC.30103@caviumnetworks.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <55A53FAC.30103@caviumnetworks.com> User-Agent: Mutt/1.5.23 (2014-03-12) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1958 Lines: 55 Hi David, On Tue, Jul 14, 2015 at 05:58:20PM +0100, David Daney wrote: > On 07/14/2015 09:29 AM, Will Deacon wrote: > > On Tue, Jul 14, 2015 at 05:12:57PM +0100, David Daney wrote: > >> Systems based on the Cavium ThunderX processor may have up to 8 > >> independent PCIe root complexes. The I/O space on each bus occupies an > >> independent physical address window. > > > > Hmm, so do you have 64k of I/O space per-bus? That gives 8x256x64k = 128M > > IIUC, so not sure what your 32MB is for. > > I don't understand where your 256 came from there. Sorry, sounds like we're mixing up buses and root complexes. Which is it? > Actually, my current implementation has 1M per bus(which is overkill). > For 8 buses I need 8M, which fits within the PCI_IO_SIZE... So there's no problem? > >> So, in order to be able to map all of these (semi) contiguously, we need > >> a lot more virtual address space than is supplied by the default values > >> for all these constants. > >> > >> The option I chose here was to unconditionally expand the I/O ranges for > >> all arm64 systems. If you think this breaks existing systems/drivers, I > >> will have to look for other options. > > > > Hmm, but pci_iomap winds up calling __pci_ioport_map, which expands to > > ioport_map which just does: > > > > return PCI_IOBASE + (port & IO_SPACE_LIMIT); > > > > so I'm struggling to see what your patch achieves. > > Here is ioport_map (from lib/iomap.c): > > > void __iomem *ioport_map(unsigned long port, unsigned int nr) > { > if (port > PIO_MASK) > return NULL; > return (void __iomem *) (unsigned long) (port + PIO_OFFSET); > } We only get this definition if CONFIG_GENERIC_IOMAP=y. Why is that selected? Will -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/