From: shinya.kuribayashi.px@renesas.com (Shinya Kuribayashi)
To: linux-arm-kernel@lists.infradead.org
Subject: [PATCH v2 2/2] ARM: delay: allow timer-based delay implementation to be selected
Date: Fri, 13 Jul 2012 11:16:41 +0900 [thread overview]
Message-ID: <4FFF8509.2050302@renesas.com> (raw)
In-Reply-To: <4FFEFDE3.5000403@codeaurora.org>
On 7/13/2012 1:40 AM, Stephen Boyd wrote:
>>>> As a result, actual udelay()s may be toooo long than expected, in
>>>> particular udelay()s used between init_current_timer_delay() and
>>>> calibrate_delay(). It's unlikely be short, as the frequency of a
>>>> counter for read_current_timer is typically slower than CPU frequency.
>>> Surely using udelay before calibrate_delay_loop has been called is a
>>> fundamental error?
>> Got it. I'm just not confident about disallowing early use of udelay().
>>
>
> I don't think it's an error. Instead you get a very large delay, similar
> to what would happen if you called udelay() before calibrate_delay()
> anyway (see the comment in init/main.c above loops_per_jiffy).
Thanks, so I'd set up loops_per_jiffy early, along with lpj_fine in
init_current_timer_delay().
As a matter of fact, I do have early use of udelay()s in my tree :-)
Will give it a try for some time.
--
Shinya Kuribayashi
Renesas Electronics
next prev parent reply other threads:[~2012-07-13 2:16 UTC|newest]
Thread overview: 38+ messages / expand[flat|nested] mbox.gz Atom feed top
2012-06-29 17:33 [PATCH v2 0/2] Use architected timers for delay loop Will Deacon
2012-06-29 17:33 ` [PATCH v2 1/2] ARM: arch timer: implement read_current_timer and get_cycles Will Deacon
2012-07-02 19:14 ` Stephen Boyd
2012-07-05 12:35 ` Shinya Kuribayashi
2012-07-05 12:59 ` Will Deacon
2012-06-29 17:33 ` [PATCH v2 2/2] ARM: delay: allow timer-based delay implementation to be selected Will Deacon
2012-07-02 19:14 ` Stephen Boyd
2012-07-02 21:53 ` Will Deacon
2012-07-03 12:09 ` Shinya Kuribayashi
2012-07-04 15:36 ` Will Deacon
2012-07-05 12:12 ` Shinya Kuribayashi
2012-07-05 12:56 ` Will Deacon
2012-07-05 16:51 ` Stephen Boyd
2012-07-05 13:06 ` Shinya Kuribayashi
2012-07-05 14:15 ` Will Deacon
2012-07-12 7:33 ` Shinya Kuribayashi
2012-07-12 8:44 ` Will Deacon
2012-07-12 9:35 ` Shinya Kuribayashi
2012-07-12 16:40 ` Stephen Boyd
2012-07-13 2:16 ` Shinya Kuribayashi [this message]
2012-07-13 8:57 ` Will Deacon
2012-07-13 10:48 ` Shilimkar, Santosh
2012-07-13 11:13 ` Will Deacon
2012-07-13 12:04 ` Shilimkar, Santosh
2012-07-13 12:08 ` Will Deacon
2012-07-13 12:14 ` Shilimkar, Santosh
2012-07-13 12:23 ` Will Deacon
2012-07-13 12:28 ` Shilimkar, Santosh
2012-07-17 3:10 ` Shinya Kuribayashi
2012-07-17 6:11 ` Shilimkar, Santosh
2012-07-17 7:42 ` Shinya Kuribayashi
2012-07-17 9:05 ` Will Deacon
2012-07-19 12:43 ` Shinya Kuribayashi
2012-07-18 17:52 ` Will Deacon
2012-07-19 15:19 ` Jonathan Austin
2012-07-20 10:17 ` Will Deacon
2012-07-24 9:06 ` Shinya Kuribayashi
2012-07-24 9:15 ` Will Deacon
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=4FFF8509.2050302@renesas.com \
--to=shinya.kuribayashi.px@renesas.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 a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).