From: Gabor Juhos <juhosg-p3rKhJxN3npAfugRpC6u6w@public.gmane.org>
To: Grant Likely <grant.likely-s3s/WqlpOiPyB63q8FvJNQ@public.gmane.org>
Cc: spi-devel-general-5NWGOfrQmneRv+LV9MX5uipxlwaOVQ5f@public.gmane.org
Subject: Re: [PATCH 1/6] spi/ath79: add delay between SCK changes
Date: Tue, 05 Feb 2013 20:52:06 +0100 [thread overview]
Message-ID: <511162E6.4050607@openwrt.org> (raw)
In-Reply-To: <20130205125719.878EE3E0E27@localhost>
Hi Grant,
> On Thu, 27 Dec 2012 10:42:24 +0100, Gabor Juhos <juhosg-p3rKhJxN3npAfugRpC6u6w@public.gmane.org> wrote:
>> The driver uses the "as fast as it can" approach
>> to drive the SCK signal. However this does not
>> work with certain low speed SPI chips (e.g. the
>> PCF2123 RTC chip).
>>
>> The patch adds per-bit slowdowns in order to be
>> able to use the driver with such chips as well.
>>
>> Signed-off-by: Gabor Juhos <juhosg-p3rKhJxN3npAfugRpC6u6w@public.gmane.org>
>
> I've applied this, but please take a second look to make sure you're not
> doing something unintended. The ndelay call will spin until it
> completes. If the current context is interrupted or scheduled out then
> it will still spin when it gets back. You may be wasting more time than
> is necessary. It would be better to check the wall time over a loop
> iteration. And if the delay required is large, then it should sleep.
Thank for the review!
Unfortunately, at the moment I don't have access to the board which uses that
PCF2123 chip but I will try to improve the code.
-Gabor
------------------------------------------------------------------------------
Free Next-Gen Firewall Hardware Offer
Buy your Sophos next-gen firewall before the end March 2013
and get the hardware for free! Learn more.
http://p.sf.net/sfu/sophos-d2d-feb
next prev parent reply other threads:[~2013-02-05 19:52 UTC|newest]
Thread overview: 15+ messages / expand[flat|nested] mbox.gz Atom feed top
2012-12-27 9:42 [PATCH 0/6] spi/ath79: various fixes Gabor Juhos
[not found] ` <1356601349-23617-1-git-send-email-juhosg-p3rKhJxN3npAfugRpC6u6w@public.gmane.org>
2012-12-27 9:42 ` [PATCH 1/6] spi/ath79: add delay between SCK changes Gabor Juhos
[not found] ` <1356601349-23617-2-git-send-email-juhosg-p3rKhJxN3npAfugRpC6u6w@public.gmane.org>
2013-02-05 12:57 ` Grant Likely
2013-02-05 19:52 ` Gabor Juhos [this message]
2012-12-27 9:42 ` [PATCH 2/6] spi/ath79: add missing HIGH->LOW SCK transition Gabor Juhos
[not found] ` <1356601349-23617-3-git-send-email-juhosg-p3rKhJxN3npAfugRpC6u6w@public.gmane.org>
2013-02-05 12:57 ` Grant Likely
2012-12-27 9:42 ` [PATCH 3/6] spi/ath79: remove superfluous chip select code Gabor Juhos
[not found] ` <1356601349-23617-4-git-send-email-juhosg-p3rKhJxN3npAfugRpC6u6w@public.gmane.org>
2013-02-05 12:58 ` Grant Likely
2012-12-27 9:42 ` [PATCH 4/6] spi/ath79: use gpio_request_one Gabor Juhos
[not found] ` <1356601349-23617-5-git-send-email-juhosg-p3rKhJxN3npAfugRpC6u6w@public.gmane.org>
2013-02-05 12:59 ` Grant Likely
2012-12-27 9:42 ` [PATCH 5/6] spi/ath79: avoid multiple initialization of the SPI controller Gabor Juhos
[not found] ` <1356601349-23617-6-git-send-email-juhosg-p3rKhJxN3npAfugRpC6u6w@public.gmane.org>
2013-02-05 13:00 ` Grant Likely
2012-12-27 9:42 ` [PATCH 6/6] spi/ath79: add shutdown handler Gabor Juhos
[not found] ` <1356601349-23617-7-git-send-email-juhosg-p3rKhJxN3npAfugRpC6u6w@public.gmane.org>
2013-02-05 13:02 ` Grant Likely
2013-02-05 19:53 ` Gabor Juhos
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=511162E6.4050607@openwrt.org \
--to=juhosg-p3rkhjxn3npafugrpc6u6w@public.gmane.org \
--cc=grant.likely-s3s/WqlpOiPyB63q8FvJNQ@public.gmane.org \
--cc=spi-devel-general-5NWGOfrQmneRv+LV9MX5uipxlwaOVQ5f@public.gmane.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.