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Message-ID: <20150204175734.GI26006@e104818-lin.cambridge.arm.com>
Date: Wed, 4 Feb 2015 17:57:34 +0000
From: Catalin Marinas <catalin.marinas@....com>
To: Mark Salter <msalter@...hat.com>
Cc: "Rafael J. Wysocki" <rjw@...ysocki.net>,
"hanjun.guo@...aro.org" <hanjun.guo@...aro.org>,
Olof Johansson <olof@...om.net>, Arnd Bergmann <arnd@...db.de>,
Mark Rutland <Mark.Rutland@....com>,
"grant.likely@...aro.org" <grant.likely@...aro.org>,
Will Deacon <Will.Deacon@....com>,
Lorenzo Pieralisi <Lorenzo.Pieralisi@....com>,
"graeme.gregory@...aro.org" <graeme.gregory@...aro.org>,
Sudeep Holla <Sudeep.Holla@....com>,
"jcm@...hat.com" <jcm@...hat.com>,
Jason Cooper <jason@...edaemon.net>,
Marc Zyngier <Marc.Zyngier@....com>,
Bjorn Helgaas <bhelgaas@...gle.com>,
Daniel Lezcano <daniel.lezcano@...aro.org>,
Mark Brown <broonie@...nel.org>, Rob Herring <robh@...nel.org>,
Robert Richter <rric@...nel.org>,
Randy Dunlap <rdunlap@...radead.org>,
Charles Garcia-Tobin <Charles.Garcia-Tobin@....com>,
"phoenix.liyi@...wei.com" <phoenix.liyi@...wei.com>,
Timur Tabi <timur@...eaurora.org>,
Ashwin Chaugule <ashwinc@...eaurora.org>,
"suravee.suthikulpanit@....com" <suravee.suthikulpanit@....com>,
Mark Langsdorf <mlangsdo@...hat.com>,
"wangyijing@...wei.com" <wangyijing@...wei.com>,
"linux-acpi@...r.kernel.org" <linux-acpi@...r.kernel.org>,
"linux-arm-kernel@...ts.infradead.org"
<linux-arm-kernel@...ts.infradead.org>,
"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
"linaro-acpi@...ts.linaro.org" <linaro-acpi@...ts.linaro.org>
Subject: Re: [PATCH v8 02/21] acpi: fix acpi_os_ioremap for arm64
On Wed, Feb 04, 2015 at 04:08:27PM +0000, Mark Salter wrote:
> On Wed, 2015-02-04 at 11:25 +0000, Catalin Marinas wrote:
> > On Tue, Feb 03, 2015 at 05:29:36PM +0000, Mark Salter wrote:
> > > On Mon, 2015-02-02 at 23:14 +0100, Rafael J. Wysocki wrote:
> > > > On Monday, February 02, 2015 08:45:30 PM Hanjun Guo wrote:
> > > > > From: Mark Salter <msalter@...hat.com>
> > > > >
> > > > > The acpi_os_ioremap() function may be used to map normal RAM or IO
> > > > > regions. The current implementation simply uses ioremap_cache(). This
> > > > > will work for some architectures, but arm64 ioremap_cache() cannot be
> > > > > used to map IO regions which don't support caching. So for arm64, use
> > > > > ioremap() for non-RAM regions.
> > > > >
> > > > > CC: Rafael J Wysocki <rjw@...ysocki.net>
> > > > > Signed-off-by: Mark Salter <msalter@...hat.com>
> > > > > Signed-off-by: Hanjun Guo <hanjun.guo@...aro.org>
> > > > > ---
> > > > > include/acpi/acpi_io.h | 6 ++++++
> > > > > 1 file changed, 6 insertions(+)
> > > > >
> > > > > diff --git a/include/acpi/acpi_io.h b/include/acpi/acpi_io.h
> > > > > index 444671e..9d573db 100644
> > > > > --- a/include/acpi/acpi_io.h
> > > > > +++ b/include/acpi/acpi_io.h
> > > > > @@ -1,11 +1,17 @@
> > > > > #ifndef _ACPI_IO_H_
> > > > > #define _ACPI_IO_H_
> > > > >
> > > > > +#include <linux/mm.h>
> > > > > #include <linux/io.h>
> > > > >
> > > > > static inline void __iomem *acpi_os_ioremap(acpi_physical_address phys,
> > > > > acpi_size size)
> > > > > {
> > > > > +#ifdef CONFIG_ARM64
> > > > > + if (!page_is_ram(phys >> PAGE_SHIFT))
> > > > > + return ioremap(phys, size);
> > > > > +#endif
> > > >
> > > > I don't want to see #ifdef CONFIG_ARM64 in this file.
> > >
> > > How about something like:
> > >
> > > From: Mark Salter <msalter@...hat.com>
> > > Date: Tue, 3 Feb 2015 10:51:16 -0500
> > > Subject: [PATCH] acpi: fix acpi_os_ioremap for arm64
> > >
> > > The acpi_os_ioremap() function may be used to map normal RAM or IO
> > > regions. The current implementation simply uses ioremap_cache(). This
> > > will work for some architectures, but arm64 ioremap_cache() cannot be
> > > used to map IO regions which don't support caching. So for arm64, use
> > > ioremap() for non-RAM regions.
> > >
> > > CC: Rafael J Wysocki <rjw@...ysocki.net>
> > > Signed-off-by: Mark Salter <msalter@...hat.com>
> > > ---
> > > arch/arm64/include/asm/acpi.h | 14 ++++++++++++++
> > > include/acpi/acpi_io.h | 3 +++
> > > 2 files changed, 17 insertions(+)
> > >
> > > diff --git a/arch/arm64/include/asm/acpi.h b/arch/arm64/include/asm/acpi.h
> > > index ea4d2b3..db82bc3 100644
> > > --- a/arch/arm64/include/asm/acpi.h
> > > +++ b/arch/arm64/include/asm/acpi.h
> > > @@ -14,6 +14,7 @@
> > >
> > > #include <linux/irqchip/arm-gic-acpi.h>
> > >
> > > +#include <linux/mm.h>
> > > #include <asm/smp_plat.h>
> > >
> > > /* Basic configuration for ACPI */
> > > @@ -100,4 +101,17 @@ static inline bool acpi_psci_use_hvc(void) { return false; }
> > > static inline void acpi_init_cpus(void) { }
> > > #endif /* CONFIG_ACPI */
> > >
> > > +/*
> > > + * ACPI table mapping
> > > + */
> > > +static inline void __iomem *acpi_os_ioremap(acpi_physical_address phys,
> > > + acpi_size size)
> > > +{
> > > + if (!page_is_ram(phys >> PAGE_SHIFT))
> > > + return ioremap(phys, size);
> > > +
> > > + return ioremap_cache(phys, size);
> > > +}
> > > +#define acpi_os_ioremap acpi_os_ioremap
> >
> > That's one way of doing this, I'm not too bothered with the approach
> > (define the function name, an ARCH_HAS macro or a Kconfig option, it's
> > up to Rafael).
> >
> > But a question I already asked is what we need ioremap_cache() for? We
> > don't use NVS on arm64 yet, so is there anything else requiring
> > cacheable mapping?
>
> acpi_os_remap() is used to map ACPI tables. These tables may be in ram
> which are already included in the kernel's linear RAM mapping. So we
> need ioremap_cache to avoid two mappings to the same physical page
> having different caching attributes.
What's the call path to acpi_os_ioremap() on such tables already in the
linear mapping? I can see an acpi_map() function which already takes
care of the RAM mapping case but there are other cases where
acpi_os_ioremap() is called directly. For example,
acpi_os_read_memory(), can it be called on both RAM and I/O?
--
Catalin
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