From: robherring2@gmail.com (Rob Herring)
To: linux-arm-kernel@lists.infradead.org
Subject: [PATCH 2/2] ARM: delay: allow timer-based delay implementation to be selected
Date: Tue, 26 Jun 2012 11:00:21 -0500 [thread overview]
Message-ID: <4FE9DC95.30408@gmail.com> (raw)
In-Reply-To: <20120626155448.GQ27996@mudshark.cambridge.arm.com>
On 06/26/2012 10:54 AM, Will Deacon wrote:
> On Tue, Jun 26, 2012 at 11:49:44AM +0100, Will Deacon wrote:
>> On Mon, Jun 25, 2012 at 10:39:10PM +0100, Stephen Boyd wrote:
>>>
>>> It's unfortunate that we have to duplicate the same code and constants
>>> in both C and assembly. With my approach we convert delay.S into C and
>>> avoid the duplication.
>>
>> It's probably easy enough to have a #define for the multiplier, I can do
>> that for v2.
>
> Looks like I spoke too soon :)
>
> The reason this is slightly problematic is due to gas's inability to
> represent unsigned constants -- namely that the 'U' suffix causes it to
> barf. I can fix it with the diff below, but please let me know what you
> think.
[snip]
> +#ifndef __ASSEMBLY__
> +
> +#define UDELAY_MULT_HZ 2199023U
> +#else
> +#define UDELAY_MULT_HZ 2199023
Doesn't UL() macro do what you need?
Rob
> +#endif /* __ASSEMBLY__ */
> +
> #endif /* defined(_ARM_DELAY_H) */
>
> diff --git a/arch/arm/lib/delay-loop.S b/arch/arm/lib/delay-loop.S
> index 1428a8f..36b668d 100644
> --- a/arch/arm/lib/delay-loop.S
> +++ b/arch/arm/lib/delay-loop.S
> @@ -9,11 +9,11 @@
> */
> #include <linux/linkage.h>
> #include <asm/assembler.h>
> -#include <asm/param.h>
> +#include <asm/delay.h>
> .text
>
> .LC0: .word loops_per_jiffy
> -.LC1: .word (2199023*HZ)>>11
> +.LC1: .word UDELAY_MULT
>
> /*
> * r0 <= 2000
> diff --git a/arch/arm/lib/delay.c b/arch/arm/lib/delay.c
> index 2b590c3..e1030e1 100644
> --- a/arch/arm/lib/delay.c
> +++ b/arch/arm/lib/delay.c
> @@ -47,12 +47,12 @@ static void __timer_const_udelay(unsigned long xloops)
> {
> unsigned long long loops = xloops;
> loops *= loops_per_jiffy;
> - __timer_delay(loops >> 30);
> + __timer_delay(loops >> UDELAY_SHIFT);
> }
>
> static void __timer_udelay(unsigned long usecs)
> {
> - __timer_const_udelay(usecs * ((2199023U * HZ) >> 11));
> + __timer_const_udelay(usecs * UDELAY_MULT);
> }
>
> void __init init_current_timer_delay(unsigned long freq)
>
> _______________________________________________
> linux-arm-kernel mailing list
> linux-arm-kernel at lists.infradead.org
> http://lists.infradead.org/mailman/listinfo/linux-arm-kernel
next prev parent reply other threads:[~2012-06-26 16:00 UTC|newest]
Thread overview: 18+ messages / expand[flat|nested] mbox.gz Atom feed top
2012-06-22 15:09 [PATCH 0/2] Use architected timers for delay loop Will Deacon
2012-06-22 15:09 ` [PATCH 1/2] ARM: arch timer: implement read_current_timer and get_cycles Will Deacon
2012-06-25 21:39 ` Stephen Boyd
2012-06-26 10:37 ` Will Deacon
2012-06-26 17:44 ` Stephen Boyd
2012-06-22 15:09 ` [PATCH 2/2] ARM: delay: allow timer-based delay implementation to be selected Will Deacon
2012-06-25 21:39 ` Stephen Boyd
2012-06-26 10:49 ` Will Deacon
2012-06-26 15:54 ` Will Deacon
2012-06-26 16:00 ` Rob Herring [this message]
2012-06-26 16:28 ` Will Deacon
2012-06-27 2:07 ` Stephen Boyd
2012-06-27 9:41 ` Will Deacon
2012-06-22 22:26 ` [PATCH 0/2] Use architected timers for delay loop Russell King - ARM Linux
2012-06-25 10:03 ` Will Deacon
2012-06-25 21:38 ` Stephen Boyd
2012-06-26 10:35 ` Will Deacon
2012-06-26 17:42 ` Stephen Boyd
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