From: "Svenning Sørensen" <sss-sijd2F9aCfdBDgjK7y7TUQ@public.gmane.org>
To: Wolfram Sang <wsa-z923LK4zBo2bacvFa/9K2g@public.gmane.org>
Cc: linux-i2c-u79uwXL29TY76Z2rM5mHXA@public.gmane.org
Subject: Re: [PATCH] i2c: scx200_acb: avoid I2C bus overclocking.
Date: Tue, 12 May 2015 23:09:53 +0200 [thread overview]
Message-ID: <55526C21.5070801@secomea.com> (raw)
In-Reply-To: <20150512201919.GL4449-oo5tB6JMkjKRinMKxDlMNPwbnWRJjS81@public.gmane.org>
On 12-05-2015 22:19, Wolfram Sang wrote:
> On Thu, Apr 23, 2015 at 10:27:50PM +0200, Svenning Sørensen wrote:
>> According to I2C spec, max SCL rate is 100 kHz, but SCx200/CS5536
>> controller is currently driving it at 214 kHz according to my math.
>>
>> SCL is derived from an input clock of 48 MHz, which must be divided
>> by 480 (240 cycles for each SCL high/low state) to be within spec.
>>
>> Signed-off-by: Svenning Soerensen <sss-sijd2F9aCfdBDgjK7y7TUQ@public.gmane.org>
>
> So, did you test/measure the actual frequency? Or is this patch based on
> specs only? Thanks for caring about this old driver, though!
>
Unfortunately I don't have any scope, so it is based on datasheet only.
I noticed sporadic i2c errors reading the temperature on some of my
PC Engines Alix.2 boards (with LM86 sensor chip) so started digging
the datasheets and driver for an explanation.
I haven't noticed any problems after this change.
next prev parent reply other threads:[~2015-05-12 21:09 UTC|newest]
Thread overview: 5+ messages / expand[flat|nested] mbox.gz Atom feed top
2015-04-23 20:27 [PATCH] i2c: scx200_acb: avoid I2C bus overclocking Svenning Sørensen
[not found] ` <553955C6.3030000-sijd2F9aCfdBDgjK7y7TUQ@public.gmane.org>
2015-05-12 20:19 ` Wolfram Sang
[not found] ` <20150512201919.GL4449-oo5tB6JMkjKRinMKxDlMNPwbnWRJjS81@public.gmane.org>
2015-05-12 21:09 ` Svenning Sørensen [this message]
2015-06-02 18:21 ` Wolfram Sang
2015-10-25 15:47 ` Wolfram Sang
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=55526C21.5070801@secomea.com \
--to=sss-sijd2f9acfdbdgjk7y7tuq@public.gmane.org \
--cc=linux-i2c-u79uwXL29TY76Z2rM5mHXA@public.gmane.org \
--cc=wsa-z923LK4zBo2bacvFa/9K2g@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 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).