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From: Will Newton <will.newton@gmail.com>
To: Russell King - ARM Linux <linux@arm.linux.org.uk>
Cc: Chris Ball <cjb@laptop.org>,
	Matt Fleming <matt@console-pimps.org>,
	linux-mmc@vger.kernel.org,
	Linux Kernel list <linux-kernel@vger.kernel.org>,
	linux-arm-kernel@lists.infradead.org
Subject: Re: [PATCH] dw_mmc: Add Synopsys DesignWare mmc host driver.
Date: Sun, 12 Dec 2010 15:17:20 +0000	[thread overview]
Message-ID: <AANLkTinr_D8GvUON5PqHSiZCAS8tQy-0YChnYD4N+zY2@mail.gmail.com> (raw)
In-Reply-To: <20101212144750.GH8665@n2100.arm.linux.org.uk>

On Sun, Dec 12, 2010 at 2:47 PM, Russell King - ARM Linux
<linux@arm.linux.org.uk> wrote:
> On Sun, Dec 12, 2010 at 02:31:40PM +0000, Will Newton wrote:
>> On Sun, Dec 12, 2010 at 2:11 PM, Russell King - ARM Linux
>> <linux@arm.linux.org.uk> wrote:
>> > Maybe invent CONFIG_HAVE_MMIO_64BIT which architectures can select as
>> > appropriate?
>>
>> Wouldn't it be simpler to have a fallback readq/writeq implementation
>> like the below?
>>
>> static inline u64 __raw_readq(const volatile void __iomem *addr)
>> {
>>         return *(const volatile u64 __force *) addr;
>> }
>>
>> It won't break any existing hardware (if your SoC bus does not support
>> 64bit accesses you are unlikely to have peripherals that require it)
>> and would avoid a number of #ifdefs and/or Kconfig dependencies.
>
> Firstly, why, then, are we discussing fixing dw_mmc.c so it builds on ARM?

It's a configurable IP block, so one would assume that if it was
configured with a 64bit FIFO width on ARM then your SoC integration
engineers dropped the ball.

Even on architectures that can do 64bit MMIO, I would expect there to
be systems where that is not safe in practice (e.g. 32bit bus fabric
that will translate a 64bit access into 2 32bit accesses) so I don't
know if it's ideal to make this an architecture level config symbol.

  reply	other threads:[~2010-12-12 15:17 UTC|newest]

Thread overview: 29+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2010-12-06 15:53 [RESEND PATCH] " Will Newton
2010-12-08 11:55 ` Matt Fleming
2010-12-08 13:14   ` Will Newton
2010-12-08 14:21     ` [PATCH] " Will Newton
2010-12-08 16:07       ` Matt Fleming
2010-12-09  6:47       ` Chris Ball
2010-12-09 12:11         ` Will Newton
2010-12-09 16:01           ` Chris Ball
2010-12-09 17:24             ` Will Newton
     [not found]               ` <20101211192320.GA24430@void.printf.net>
2010-12-12  8:41                 ` Russell King - ARM Linux
2010-12-12 11:15                   ` Russell King - ARM Linux
2010-12-12 10:57                 ` Will Newton
2010-12-12 13:52                   ` Chris Ball
2010-12-12 14:03                     ` Will Newton
2010-12-12 14:11                       ` Russell King - ARM Linux
2010-12-12 14:31                         ` Will Newton
2010-12-12 14:47                           ` Russell King - ARM Linux
2010-12-12 15:17                             ` Will Newton [this message]
2010-12-16 17:04                 ` [PATCH v4] " Will Newton
2011-01-02  6:20                   ` Chris Ball
2011-01-18  7:54                   ` Jaehoon Chung
2011-01-18 10:21                     ` Will Newton
2011-02-08  6:38                       ` Jaehoon Chung
2011-02-08 10:29                         ` Will Newton
2011-02-08 10:49                           ` Jaehoon Chung
2011-02-08 12:06                             ` Will Newton
2010-12-09 17:35             ` [PATCH] " Chris Ball
2010-12-09 17:46               ` Will Newton
  -- strict thread matches above, loose matches on Subject: below --
2010-11-29 17:35 Will Newton

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