From: Wolfram Sang <wsa@the-dreams.de>
To: Barry Song <21cnbao@gmail.com>
Cc: linux-i2c@vger.kernel.org, workgroup.linux@csr.com,
Guoying Zhang <Guoying.Zhang@csr.com>,
Barry Song <Baohua.Song@csr.com>
Subject: Re: [PATCH] i2c: sirf: tune the divider to make i2c bus freq more accurate
Date: Fri, 23 Oct 2015 22:30:52 +0200 [thread overview]
Message-ID: <20151023203052.GI1520@katana> (raw)
In-Reply-To: <1441794632-4074-1-git-send-email-21cnbao@gmail.com>
[-- Attachment #1: Type: text/plain, Size: 1064 bytes --]
On Wed, Sep 09, 2015 at 10:30:32AM +0000, Barry Song wrote:
> From: Guoying Zhang <Guoying.Zhang@csr.com>
>
> In prima2 and atlas7, due to some hardware design issue. we
> need to adjust the divider ratio a little according to i2c
> bus frequency ranges.
> Since i2c is open drain interface that allows the slave to
> stall the transaction by holding the SCL line at '0', the RTL
> implementation is waiting for SCL feedback from the pin after
> setting it to High-Z ('1'). This wait adds to the high-time
> interval counter few cycles of the input synchronization
> (depending on the SCL_FILTER_REG field), and also the time it
> takes for the board pull-up resistor to rise the SCL line.
> For slow SCL settings these additions are negligible, but they
> start to affect the speed when clock is set to faster frequencies.
> This patch is based on the actual tests, and it makes SCL more
> accurate.
>
> Signed-off-by: Guoying Zhang <Guoying.Zhang@csr.com>
> Signed-off-by: Barry Song <Baohua.Song@csr.com>
Applied to for-next, thanks!
[-- Attachment #2: Digital signature --]
[-- Type: application/pgp-signature, Size: 819 bytes --]
prev parent reply other threads:[~2015-10-23 20:30 UTC|newest]
Thread overview: 2+ messages / expand[flat|nested] mbox.gz Atom feed top
2015-09-09 10:30 [PATCH] i2c: sirf: tune the divider to make i2c bus freq more accurate Barry Song
2015-10-23 20:30 ` Wolfram Sang [this message]
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=20151023203052.GI1520@katana \
--to=wsa@the-dreams.de \
--cc=21cnbao@gmail.com \
--cc=Baohua.Song@csr.com \
--cc=Guoying.Zhang@csr.com \
--cc=linux-i2c@vger.kernel.org \
--cc=workgroup.linux@csr.com \
/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).