linux-arm-kernel.lists.infradead.org archive mirror
 help / color / mirror / Atom feed
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

  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).