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
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=4FE9DC95.30408@gmail.com \
--to=robherring2@gmail.com \
--cc=linux-arm-kernel@lists.infradead.org \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is an external index of several public inboxes,
see mirroring instructions on how to clone and mirror
all data and code used by this external index.