Re: [PATCH v8 02/21] acpi: fix acpi_os_ioremap for arm64

[Mark Salter]

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@xxxxxxxxxx>
> > > > 
> > > > 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@xxxxxxxxxxxxx>
> > > > Signed-off-by: Mark Salter <msalter@xxxxxxxxxx>
> > > > Signed-off-by: Hanjun Guo <hanjun.guo@xxxxxxxxxx>
> > > > ---
> > > >  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@xxxxxxxxxx>
> > 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@xxxxxxxxxxxxx>
> > Signed-off-by: Mark Salter <msalter@xxxxxxxxxx>
> > ---
> >  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.


--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/