linux-kernel - Re: [PATCH v8 02/21] acpi: fix acpi_os

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Message-ID: <20150204104832.GF8656@n2100.arm.linux.org.uk>
Date:	Wed, 4 Feb 2015 10:48:32 +0000
From:	Russell King - ARM Linux <linux@....linux.org.uk>
To:	"Rafael J. Wysocki" <rjw@...ysocki.net>
Cc:	Mark Salter <msalter@...hat.com>,
	Mark Rutland <mark.rutland@....com>,
	Mark Langsdorf <mlangsdo@...hat.com>,
	linaro-acpi@...ts.linaro.org,
	Catalin Marinas <catalin.marinas@....com>,
	Will Deacon <will.deacon@....com>, wangyijing@...wei.com,
	Rob Herring <robh@...nel.org>,
	Lorenzo Pieralisi <Lorenzo.Pieralisi@....com>,
	Timur Tabi <timur@...eaurora.org>,
	Daniel Lezcano <daniel.lezcano@...aro.org>,
	linux-acpi@...r.kernel.org, Grant Likely <grant.likely@...aro.org>,
	Charles.Garcia-Tobin@....com, phoenix.liyi@...wei.com,
	Robert Richter <rric@...nel.org>,
	Jason Cooper <jason@...edaemon.net>,
	Arnd Bergmann <arnd@...db.de>,
	Marc Zyngier <marc.zyngier@....com>,
	Jon Masters <jcm@...hat.com>, Mark Brown <broonie@...nel.org>,
	Bjorn Helgaas <bhelgaas@...gle.com>,
	linux-arm-kernel@...ts.infradead.org,
	Ashwin Chaugule <ashwinc@...eaurora.org>,
	Graeme Gregory <graeme.gregory@...aro.org>,
	Randy Dunlap <rdunlap@...radead.org>,
	linux-kernel@...r.kernel.org, Hanjun Guo <hanjun.guo@...aro.org>,
	suravee.suthikulpanit@....com, Sudeep Holla <Sudeep.Holla@....com>,
	Olof Johansson <olof@...om.net>
Subject: Re: [PATCH v8 02/21] acpi: fix acpi_os_ioremap for arm64

On Tue, Feb 03, 2015 at 11:04:27PM +0100, Rafael J. Wysocki wrote:
> On Tuesday, February 03, 2015 12:29:36 PM 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
> 
> If you want to do it this way, use __weak.  You won't need the #define then.
> Otherwise, please use a proper CONFIG_ARCH_ symbol.

How does __weak work with inline functions?  I don't believe it does.

Moreover, __weak is positively harmful when you consider it adds bloat
and dead code - the overriden __weak function is left behind in the
resulting final image.

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