linux-kernel - Re: [PATCH 00/20] PCI: fix config and I/O Address space memory mappings

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Date:   Thu, 2 Mar 2017 18:00:57 +0000
From:   Lorenzo Pieralisi <lorenzo.pieralisi@....com>
To:     Arnd Bergmann <arnd@...db.de>
Cc:     linux-pci <linux-pci@...r.kernel.org>,
        Linux ARM <linux-arm-kernel@...ts.infradead.org>,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
        linux-arch <linux-arch@...r.kernel.org>,
        Pratyush Anand <pratyush.anand@...il.com>,
        Jonathan Corbet <corbet@....net>,
        Will Deacon <will.deacon@....com>,
        Jingoo Han <jingoohan1@...il.com>,
        Bjorn Helgaas <bhelgaas@...gle.com>,
        Mingkai Hu <mingkai.hu@...escale.com>,
        Tanmay Inamdar <tinamdar@....com>,
        Murali Karicheri <m-karicheri2@...com>,
        Russell King <linux@...linux.org.uk>,
        Bharat Kumar Gogada <bharat.kumar.gogada@...inx.com>,
        Ray Jui <rjui@...adcom.com>,
        Wenrui Li <wenrui.li@...k-chips.com>,
        Shawn Lin <shawn.lin@...k-chips.com>,
        Minghuan Lian <minghuan.Lian@...escale.com>,
        Catalin Marinas <catalin.marinas@....com>,
        Jon Mason <jonmason@...adcom.com>,
        Gabriele Paoloni <gabriele.paoloni@...wei.com>,
        Thomas Petazzoni <thomas.petazzoni@...e-electrons.com>,
        Joao Pinto <Joao.Pinto@...opsys.com>,
        Thierry Reding <thierry.reding@...il.com>,
        Michal Simek <michal.simek@...inx.com>,
        Stanimir Varbanov <svarbanov@...sol.com>,
        Zhou Wang <wangzhou1@...ilicon.com>,
        Roy Zang <tie-fei.zang@...escale.com>,
        John Garry <john.garry@...wei.com>
Subject: Re: [PATCH 00/20] PCI: fix config and I/O Address space memory
 mappings

On Wed, Mar 01, 2017 at 05:18:27PM +0100, Arnd Bergmann wrote:
> On Mon, Feb 27, 2017 at 4:14 PM, Lorenzo Pieralisi
> <lorenzo.pieralisi@....com> wrote:
> 
> > This patch series[1] addresses both issues in one go:
> >
> > - It updates the pci_remap_iospace() function to use a page mapping
> >   that guarantees non-posted write transactions for I/O space addresses
> > - It adds a kernel API to remap PCI config space resources, so that
> >   architecture can override it with a mapping implementation that
> >   guarantees PCI specifications compliancy wrt non-posted write
> >   configuration transactions
> > - It updates all PCI host controller implementations (and the generic
> >   ECAM layer) to use the newly introduced mapping interface
> >
> > Tested on Juno ECAM based interface (DT/ACPI).
> 
> This looks all good to me, nice work!

Thanks a lot Arnd. There is a pending issue to complete the series,
that is related to asm-generic/io.h, which is not included by all
arches, therefore, on top of adding a default inline for
pci_remap_cfg_space() in asm-generic/io.h I will have to patch
all arches that do not include asm-generic/io.h (eg x86) to
make the series completely functional - ie I will have to add a

#define pci_remap_cfgspace ioremap_nocache

in every given asm/io.h that does not include <asm-generic/io.h>

Another option would consist in adding the default inline for
pci_remap_cfg_space() in asm-generic/pci_iomap.h which seems to
be included by all arches.

I think the first option, even if it requires more extensive
patching is more complete but please all let me know how
you want me to fix this niggle, I am not sure I grasp the background
policy behind asm-generic files entirely so I'd better ask.

Thanks !
Lorenzo