From: troy.kisky@boundarydevices.com (Troy Kisky)
To: linux-arm-kernel@lists.infradead.org
Subject: [PATCH] i2c i.MX: Fix divider table
Date: Wed, 11 Jul 2012 12:11:23 -0700 [thread overview]
Message-ID: <4FFDCFDB.7020402@boundarydevices.com> (raw)
In-Reply-To: <20120711183838.GM30009@pengutronix.de>
On 7/11/2012 11:38 AM, Sascha Hauer wrote:
> Hi Richard,
>
> On Wed, Jul 11, 2012 at 02:01:21PM +0800, Richard Zhao wrote:
>> IC guys confirmed that the spec is right:
>>
>> This an adaptive feature of our I2C module may apply to all IMX chips.
>> No mistake in the table of RMs.
>>
>> The divider is designed to guarantee SCL high level and low level last
>> time. Divider will hold when SCL transition from 1 to 0 or 0 to 1, if
>> the transition time is longer than 1 internal pre-divided clock cycle.
>> The pre-divided clock is divided from I2C module clock, used for
>> generating SCL. So you will see SCL clock cycle is some way longer than
>> calculated value using IFDR.
>>
>> Transition time will different from rising or falling edge, different
>> pull-up resistors, and different SCL loading.
>>
>> This feature make sure transition time won?t eat both level time of SCL.
> Thanks for clarification. Does this mean that this feature is used to
> synchronize between the bus clock and and bitclock?
>
> I'll send a documentation patch for this next week to make this clear.
>
> Sascha
>
How does this explain why column 2 matched your measurements, but 1, 3,
and 4 didn't.
And you tested on 2 different boards.
Something doesn't smell right.
Just my 2cents
Troy
next prev parent reply other threads:[~2012-07-11 19:11 UTC|newest]
Thread overview: 15+ messages / expand[flat|nested] mbox.gz Atom feed top
2012-07-05 13:10 [PATCH] i2c i.MX: Fix divider table Sascha Hauer
2012-07-05 14:23 ` Baruch Siach
2012-07-05 14:52 ` Richard Zhao
2012-07-05 16:01 ` Sascha Hauer
2012-07-06 0:52 ` Richard Zhao
2012-07-06 6:28 ` Sascha Hauer
2012-07-06 17:41 ` Troy Kisky
2012-07-11 6:01 ` Richard Zhao
2012-07-11 18:38 ` Sascha Hauer
2012-07-11 19:11 ` Troy Kisky [this message]
2012-07-11 19:44 ` Sascha Hauer
2012-07-12 0:45 ` Richard Zhao
2012-07-05 18:06 ` Shubhrajyoti Datta
2012-07-05 18:47 ` Sascha Hauer
2012-07-08 9:14 ` Shubhrajyoti Datta
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=4FFDCFDB.7020402@boundarydevices.com \
--to=troy.kisky@boundarydevices.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).