[PATCH v2 1/5] ARM: omap4: Correct definition of do_wfi() forCONFIG_THUMB2_KERNEL

-----Original Message-----
From: Dave Martin [mailto:dave.martin at linaro.org]
Sent: Friday, February 04, 2011 4:28 PM
To: Santosh Shilimkar
Cc: Russell King - ARM Linux; linux-arm-kernel at lists.infradead.org;
Tony Lindgren; Nicolas Pitre; linux-omap at vger.kernel.org; Jean
Pihet-XID
Subject: Re: [PATCH v2 1/5] ARM: omap4: Correct definition of
do_wfi() forCONFIG_THUMB2_KERNEL

On Thu, Feb 3, 2011 at 7:30 PM, Santosh Shilimkar
[off-list ref] wrote:

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-----Original Message-----

[....]

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We actually have this:

#if __LINUX_ARM_ARCH__ >= 7 || ? ? ? ? ?\
? ? ? ? (__LINUX_ARM_ARCH__ == 6 && defined(CONFIG_CPU_32v6K))
#define sev() ? __asm__ __volatile__ ("sev" : : : "memory")
#define wfe() ? __asm__ __volatile__ ("wfe" : : : "memory")
#define wfi() ? __asm__ __volatile__ ("wfi" : : : "memory")
#endif

in asm/system.h, so maybe it should be using wfe() from

asm/system.h

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?

I assume you mean wfi here.
The problem is, omap2plus build breaks because it builds
CPU_32v6 and CPU_32v7 as well which doesn't support the wfi
instruction. Hence I used opcode directly to keep build
working.

I guess that's right, OMAP2 is ARM1136 and doesn't have the K
extensions.

Would it make sense to have the v6 MCR equivalent as an altetnative?
Something like:

#elseif __LINUX_ARM_ARCH__ >= 6
#define wfi()   __asm__ __volatile__ ( \
    "mov     r0, #0\n\t" \
    "mcr     p15, 0, r0, c7, c0, 4\n\t" \
    ::: "r0"
)
#endif

This MCR is a mandatory part of the architecture for v6, but it's
not
mandatory for older processors.

That should do as well.

Regards,
Santosh