From: Arnd Bergmann <arnd@arndb.de>
To: "Russell King - ARM Linux" <linux@arm.linux.org.uk>
Cc: linux-arm-kernel@lists.infradead.org,
linux-kernel@vger.kernel.org, Will Deacon <will.deacon@arm.com>,
Nicolas Pitre <nico@linaro.org>,
"James E.J. Bottomley" <JBottomley@parallels.com>,
linux-scsi@vger.kernel.org
Subject: Re: [PATCH 22/24] scsi: eesox: use __iomem pointers for MMIO
Date: Sat, 15 Sep 2012 10:30:43 +0000 [thread overview]
Message-ID: <201209151030.44105.arnd@arndb.de> (raw)
In-Reply-To: <20120915085734.GG12245@n2100.arm.linux.org.uk>
On Saturday 15 September 2012, Russell King - ARM Linux wrote:
> On Sat, Sep 15, 2012 at 08:00:35AM +0000, Arnd Bergmann wrote:
> > On Friday 14 September 2012, Russell King - ARM Linux wrote:
> > > On Fri, Sep 14, 2012 at 11:34:50PM +0200, Arnd Bergmann wrote:
> > > > ARM is moving to stricter checks on readl/write functions,
> > > > so we need to use the correct types everywhere.
> > >
> > > There's nothing wrong with const iomem pointers. If you think
> > > otherwise, patch x86 not to use const in its accessor implementation
> > > and watch the reaction:
> > >
> > > #define build_mmio_read(name, size, type, reg, barrier) \
> > > static inline type name(const volatile void __iomem *addr) \
> > > { type ret; asm volatile("mov" size " %1,%0":reg (ret) \
> > > :"m" (*(volatile type __force *)addr) barrier); return ret; }
> > >
> > > build_mmio_read(readb, "b", unsigned char, "=q", :"memory")
> > > build_mmio_read(readw, "w", unsigned short, "=r", :"memory")
> > > build_mmio_read(readl, "l", unsigned int, "=r", :"memory")
> >
> > Ok, fair enough. Can you fold the patch below into
> > "ARM: 7500/1: io: avoid writeback addressing modes for __raw_
> > accessors", or apply on top then?
>
> No - const is not appropriate for the write accessors. Again, this puts
> us at odds with x86:
>
> #define build_mmio_write(name, size, type, reg, barrier) \
> static inline void name(type val, volatile void __iomem *addr) \
> { asm volatile("mov" size " %0,%1": :reg (val), \
> "m" (*(volatile type __force *)addr) barrier); }
>
> build_mmio_write(writeb, "b", unsigned char, "q", :"memory")
> build_mmio_write(writew, "w", unsigned short, "r", :"memory")
> build_mmio_write(writel, "l", unsigned int, "r", :"memory")
>
> So, readl etc are all const volatile void __iomem *, but writel etc are
> all volatile void __iomem *.
>
> How they're defined on ARM after 7500/1 copies how they're defined on
> x86.
Well, you have to make up your mind what you want. Right now, we get these
warnings in rpc_defconfig:
Generating include/generated/mach-types.h
/home/arnd/linux-arm/drivers/net/ethernet/seeq/ether3.c: In function 'ether3_outb':
/home/arnd/linux-arm/drivers/net/ethernet/seeq/ether3.c:104:2: error: passing argument 2 of '__raw_writeb' discards 'const' qualifier from pointer target type [-Werror]
/home/arnd/linux-arm/arch/arm/include/asm/io.h:81:91: note: expected 'volatile void *' but argument is of type 'const void *'
/home/arnd/linux-arm/drivers/scsi/arm/eesox.c: In function 'eesoxscsi_buffer_out':
/home/arnd/linux-arm/drivers/scsi/arm/eesox.c:310:4: error: passing argument 2 of '__raw_writel' discards 'const' qualifier from pointer target type [-Werror]
/home/arnd/linux-arm/arch/arm/include/asm/io.h:88:91: note: expected 'volatile void *' but argument is of type 'const void *'
/home/arnd/linux-arm/drivers/scsi/arm/eesox.c:324:4: error: passing argument 2 of '__raw_writel' discards 'const' qualifier from pointer target type [-Werror]
/home/arnd/linux-arm/arch/arm/include/asm/io.h:88:91: note: expected 'volatile void *' but argument is of type 'const void *'
/home/arnd/linux-arm/drivers/scsi/arm/eesox.c:325:4: error: passing argument 2 of '__raw_writel' discards 'const' qualifier from pointer target type [-Werror]
/home/arnd/linux-arm/arch/arm/include/asm/io.h:88:91: note: expected 'volatile void *' but argument is of type 'const void *'
Either we allow drivers to write to const __iomem pointers or we don't. I
don't care which way we do it, but just saying both patches are wrong is
not very helpful.
Arnd
next prev parent reply other threads:[~2012-09-15 10:30 UTC|newest]
Thread overview: 71+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <1347658492-11608-1-git-send-email-arnd@arndb.de>
2012-09-14 21:34 ` [PATCH 01/24] ARM: shmobile: use __iomem pointers for MMIO Arnd Bergmann
2012-09-18 7:11 ` Simon Horman
2012-09-18 8:31 ` Arnd Bergmann
2012-09-18 11:50 ` Simon Horman
2012-09-18 16:04 ` Arnd Bergmann
2012-09-18 23:56 ` Simon Horman
2012-09-18 7:42 ` Paul Mundt
2012-09-14 21:34 ` [PATCH 02/24] ARM: at91: " Arnd Bergmann
2012-09-17 7:56 ` Nicolas Ferre
2012-09-18 8:05 ` Arnd Bergmann
2012-09-14 21:34 ` [PATCH 03/24] ARM: ebsa110: " Arnd Bergmann
2012-09-14 21:34 ` [PATCH 04/24] ARM: ep93xx: " Arnd Bergmann
2012-09-14 22:14 ` Ryan Mallon
2012-09-15 7:55 ` Arnd Bergmann
2012-09-14 21:34 ` [PATCH 05/24] ARM: imx: " Arnd Bergmann
2012-09-14 22:31 ` Fabio Estevam
2012-09-15 17:42 ` Arnd Bergmann
2012-09-16 7:21 ` Sascha Hauer
2012-09-14 21:34 ` [PATCH 06/24] ARM: integrator: " Arnd Bergmann
2012-09-16 22:19 ` Linus Walleij
2012-09-16 22:35 ` Russell King - ARM Linux
2012-09-16 22:46 ` Linus Walleij
2012-09-16 23:43 ` Russell King - ARM Linux
2012-09-14 21:34 ` [PATCH 07/24] ARM: iop13xx: " Arnd Bergmann
2012-09-14 21:34 ` [PATCH 08/24] ARM: iop32x: " Arnd Bergmann
2012-09-14 21:34 ` [PATCH 09/24] ARM: ixp4xx: " Arnd Bergmann
2012-09-18 10:31 ` Krzysztof Halasa
2012-09-18 19:22 ` Krzysztof Halasa
2012-09-19 13:52 ` Arnd Bergmann
2012-09-18 20:12 ` [PATCH 08+09/24] " Krzysztof Halasa
2012-09-18 21:25 ` Arnd Bergmann
2012-09-14 21:34 ` [PATCH 10/24] ARM: ks8695: " Arnd Bergmann
2012-09-14 21:34 ` [PATCH 11/24] ARM: lpc32xx: " Arnd Bergmann
2012-09-14 21:34 ` [PATCH 12/24] ARM: msm: " Arnd Bergmann
2012-09-14 22:38 ` Stephen Boyd
2012-09-15 5:16 ` David Brown
2012-09-14 21:34 ` [PATCH 13/24] ARM: nomadik: " Arnd Bergmann
2012-09-16 22:24 ` Linus Walleij
2012-09-14 21:34 ` [PATCH 14/24] ARM: prima2: " Arnd Bergmann
2012-09-14 21:34 ` [PATCH 15/24] ARM: sa1100: " Arnd Bergmann
2012-09-14 21:34 ` [PATCH 16/24] ARM: spear13xx: " Arnd Bergmann
2012-09-14 21:34 ` [PATCH 17/24] ARM: OMAP: " Arnd Bergmann
2012-09-15 18:10 ` Tony Lindgren
2012-09-15 20:14 ` Arnd Bergmann
2012-09-16 20:38 ` Tony Lindgren
2012-09-17 21:25 ` Tony Lindgren
2012-09-19 13:35 ` Arnd Bergmann
2012-09-19 13:36 ` Felipe Balbi
2012-09-19 16:44 ` Tony Lindgren
2012-09-14 21:34 ` [PATCH 18/24] ARM: samsung: " Arnd Bergmann
2012-09-14 21:34 ` [PATCH 19/24] sh: " Arnd Bergmann
2012-09-18 7:37 ` Paul Mundt
2012-09-18 8:01 ` Arnd Bergmann
2012-09-14 21:34 ` [PATCH 20/24] input: rpcmouse: " Arnd Bergmann
2012-09-19 17:06 ` Dmitry Torokhov
2012-09-14 21:34 ` [PATCH 21/24] serial: ks8695: " Arnd Bergmann
2012-09-14 23:44 ` Greg Kroah-Hartman
2012-09-14 21:34 ` [PATCH 22/24] scsi: eesox: " Arnd Bergmann
2012-09-14 23:27 ` Russell King - ARM Linux
2012-09-15 8:00 ` Arnd Bergmann
2012-09-15 8:57 ` Russell King - ARM Linux
2012-09-15 10:30 ` Arnd Bergmann [this message]
2012-09-17 22:03 ` Russell King - ARM Linux
2012-09-18 8:09 ` Arnd Bergmann
2012-09-14 21:34 ` [PATCH 23/24] video: da8xx-fb: " Arnd Bergmann
2012-09-14 21:34 ` [PATCH 24/24] net: seeq: " Arnd Bergmann
2012-09-14 23:56 ` Russell King - ARM Linux
2012-09-15 4:00 ` David Miller
2012-09-18 8:14 ` Arnd Bergmann
2012-09-15 11:33 ` [PATCH 13/24] ARM: nomadik: " Alessandro Rubini
2012-09-28 20:13 ` Arnd Bergmann
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