From: Wolfram Sang <wsa@kernel.org>
To: Mark Jonas <mark.jonas@de.bosch.com>
Cc: Support Opensource <support.opensource@diasemi.com>,
Lee Jones <lee.jones@linaro.org>,
linux-kernel@vger.kernel.org, linux-i2c@vger.kernel.org,
Adam.Thomson.Opensource@diasemi.com,
stwiss.opensource@diasemi.com, marek.vasut@gmail.com,
tingquan.ruan@cn.bosch.com, hubert.streidl@de.bosch.com
Subject: Re: [PATCH v6 1/1] mfd: da9063: Support SMBus and I2C mode
Date: Tue, 16 Mar 2021 18:00:33 +0100 [thread overview]
Message-ID: <20210316170033.GB1110@ninjato> (raw)
In-Reply-To: <20210316162237.877436-1-mark.jonas@de.bosch.com>
[-- Attachment #1: Type: text/plain, Size: 1510 bytes --]
On Tue, Mar 16, 2021 at 05:22:37PM +0100, Mark Jonas wrote:
> From: Hubert Streidl <hubert.streidl@de.bosch.com>
>
> By default the PMIC DA9063 2-wire interface is SMBus compliant. This
> means the PMIC will automatically reset the interface when the clock
> signal ceases for more than the SMBus timeout of 35 ms.
>
> If the I2C driver / device is not capable of creating atomic I2C
> transactions, a context change can cause a ceasing of the clock signal.
> This can happen if for example a real-time thread is scheduled. Then
> the DA9063 in SMBus mode will reset the 2-wire interface. Subsequently
> a write message could end up in the wrong register. This could cause
> unpredictable system behavior.
>
> The DA9063 PMIC also supports an I2C compliant mode for the 2-wire
> interface. This mode does not reset the interface when the clock
> signal ceases. Thus the problem depicted above does not occur.
>
> This patch tests for the bus functionality "I2C_FUNC_I2C". It can
> reasonably be assumed that the bus cannot obey SMBus timings if
> this functionality is set. SMBus commands most probably are emulated
> in this case which is prone to the latency issue described above.
>
> This patch enables the I2C bus mode if I2C_FUNC_I2C is set or
> otherwise keeps the default SMBus mode.
>
> Signed-off-by: Hubert Streidl <hubert.streidl@de.bosch.com>
> Signed-off-by: Mark Jonas <mark.jonas@de.bosch.com>
Reviewed-by: Wolfram Sang <wsa+renesas@sang-engineering.com>
[-- Attachment #2: signature.asc --]
[-- Type: application/pgp-signature, Size: 833 bytes --]
next prev parent reply other threads:[~2021-03-16 17:01 UTC|newest]
Thread overview: 6+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-03-16 16:22 [PATCH v6 1/1] mfd: da9063: Support SMBus and I2C mode Mark Jonas
2021-03-16 17:00 ` Wolfram Sang [this message]
2021-03-16 17:07 ` Lee Jones
2021-03-17 13:37 ` AW: " Jonas Mark (BT-FIR/ENG1-Grb)
2021-03-17 13:43 ` Lee Jones
2021-03-17 9:30 ` Adam Thomson
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=20210316170033.GB1110@ninjato \
--to=wsa@kernel.org \
--cc=Adam.Thomson.Opensource@diasemi.com \
--cc=hubert.streidl@de.bosch.com \
--cc=lee.jones@linaro.org \
--cc=linux-i2c@vger.kernel.org \
--cc=linux-kernel@vger.kernel.org \
--cc=marek.vasut@gmail.com \
--cc=mark.jonas@de.bosch.com \
--cc=stwiss.opensource@diasemi.com \
--cc=support.opensource@diasemi.com \
--cc=tingquan.ruan@cn.bosch.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).