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From: thierry.reding@gmail•com (Thierry Reding)
To: linux-arm-kernel@lists•infradead.org
Subject: [PATCHv7 1/4] pwm: Add Freescale FTM PWM driver support
Date: Tue, 17 Dec 2013 14:22:48 +0100	[thread overview]
Message-ID: <20131217132247.GB2329@ulmo.nvidia.com> (raw)
In-Reply-To: <20131217130435.GV4360@n2100.arm.linux.org.uk>

On Tue, Dec 17, 2013 at 01:04:35PM +0000, Russell King - ARM Linux wrote:
> On Tue, Dec 17, 2013 at 01:54:35PM +0100, Tomasz Figa wrote:
> > On Tuesday 17 of December 2013 13:45:06 Thierry Reding wrote:
> > > I fail to see how that would eliminate the problem with the types. That
> > > said I don't actually see sparse complaining about any type mismatches.
> > > That's probably because the various macros implicitly cast to u32.
> > 
> > Well, in BE variant you would read the register using __raw_readl() into
> > a __be32 and then get an u32 from be32_to_cpu() and return it. Similarly
> > for writes
> 
> __raw_readl() returns a u32, so you'll get a warning trying to assign a
> u32 to a __be32.

If sparse doesn't complain about the original code here, does that mean
we have a bug that should be fixed?

> We do have ioread32() and ioread32be() which do the appropriate conversion,
> as well as the write versions too.  They both include the barrier if you're
> overly concerned about that.

A few years ago GregKH commented in response to a patch that ioread*()
weren't supposed to be used for memory-mapped only devices. The original
purpose apparently was to allow drivers to work with both I/O and
memory-mapped devices.

Thierry
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  parent reply	other threads:[~2013-12-17 13:22 UTC|newest]

Thread overview: 19+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2013-12-13  8:57 [PATCHv7 0/4] Add Freescale FTM PWM driver Xiubo Li
2013-12-13  8:57 ` [PATCHv7 1/4] pwm: Add Freescale FTM PWM driver support Xiubo Li
2013-12-17 11:10   ` Thierry Reding
2013-12-17 11:51     ` Russell King - ARM Linux
2013-12-17 12:00       ` Tomasz Figa
2013-12-17 12:45         ` Thierry Reding
2013-12-17 12:54           ` Tomasz Figa
2013-12-17 13:04             ` Russell King - ARM Linux
2013-12-17 13:08               ` Tomasz Figa
2013-12-17 13:22               ` Thierry Reding [this message]
2013-12-18  9:43               ` Li.Xiubo at freescale.com
2013-12-18  6:28           ` Li.Xiubo at freescale.com
2013-12-17 12:24       ` Thierry Reding
2013-12-17 12:58         ` Russell King - ARM Linux
2013-12-17 13:19           ` Thierry Reding
2013-12-18  3:34     ` Li.Xiubo at freescale.com
2013-12-13  8:57 ` [PATCHv7 2/4] ARM: dts: Add Freescale FTM PWM node for VF610 Xiubo Li
2013-12-13  8:57 ` [PATCHv7 3/4] ARM: dts: Enables FTM PWM device for Vybrid VF610 TOWER board Xiubo Li
2013-12-13  8:57 ` [PATCHv7 4/4] Documentation: Add device tree bindings for Freescale FTM PWM Xiubo Li

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