[PATCH 2/3] [ARM] Allow machines to override __delay()
dwalker at codeaurora.org
Tue Oct 5 13:29:38 EDT 2010
On Mon, 2010-09-27 at 20:33 -0700, Stephen Boyd wrote:
> Some machines want to implement their own __delay() routine based
> on fixed timers. Expose functionality to set the __delay()
> routine at runtime. This should allow two machines with different
> __delay() routines to happily co-exist within the same kernel
> with minimal overhead.
Say "This allows developers to implement their own __delay() ..."
> Russell expressed concern that using a timer based __delay()
> would cause problems where an iomapped device isn't mapped in
> before a delay call was made (see
> http://article.gmane.org/gmane.linux.ports.arm.kernel/78543 for
> more info). We can sidestep that issue with this approach since
> the __delay() routine _should_ only be pointed to a timer based
> delay once the timer has been properly mapped. Up until that
> point __delay() and udelay() will use delay_loop() which is
> always safe to call.
> This patch is inspired by x86's delay.c
> Signed-off-by: Stephen Boyd <sboyd at codeaurora.org>
> Reviewed-by: Saravana Kannan <skannan at codeaurora.org>
> arch/arm/include/asm/delay.h | 2 ++
> arch/arm/lib/delay.c | 21 ++++++++++++++++++---
> 2 files changed, 20 insertions(+), 3 deletions(-)
> diff --git a/arch/arm/include/asm/delay.h b/arch/arm/include/asm/delay.h
> index ccc5ed5..7c732b5 100644
> --- a/arch/arm/include/asm/delay.h
> +++ b/arch/arm/include/asm/delay.h
> @@ -40,5 +40,7 @@ extern void __const_udelay(unsigned long);
> __const_udelay((n) * ((2199023U*HZ)>>11))) : \
> +extern void set_delay_fn(void (*fn)(unsigned long));
> #endif /* defined(_ARM_DELAY_H) */
> diff --git a/arch/arm/lib/delay.c b/arch/arm/lib/delay.c
> index 5ee0adc..b307fcc 100644
> --- a/arch/arm/lib/delay.c
> +++ b/arch/arm/lib/delay.c
> @@ -3,6 +3,8 @@
> * Copyright (C) 1995, 1996 Russell King
> * Copyright (c) 2010, Code Aurora Forum. All rights reserved.
> + * Copyright (C) 1993 Linus Torvalds
> + * Copyright (C) 1997 Martin Mares <mj at atrey.karlin.mff.cuni.cz>
Who is Martin Mares? Why are you adding these?
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