From: Adam Thomson <Adam.Thomson.Opensource@diasemi.com>
To: Mark Jonas <mark.jonas@de.bosch.com>,
Support Opensource <Support.Opensource@diasemi.com>,
Lee Jones <lee.jones@linaro.org>
Cc: "linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
"linux-i2c@vger.kernel.org" <linux-i2c@vger.kernel.org>,
Adam Thomson <Adam.Thomson.Opensource@diasemi.com>,
Steve Twiss <stwiss.opensource@diasemi.com>,
"marek.vasut@gmail.com" <marek.vasut@gmail.com>,
"tingquan.ruan@cn.bosch.com" <tingquan.ruan@cn.bosch.com>,
"hubert.streidl@de.bosch.com" <hubert.streidl@de.bosch.com>,
Wolfram Sang <wsa@kernel.org>
Subject: RE: [PATCH v6 1/1] mfd: da9063: Support SMBus and I2C mode
Date: Wed, 17 Mar 2021 09:30:10 +0000 [thread overview]
Message-ID: <PR3PR10MB41425F5C553DC7F5E67F6A77806A9@PR3PR10MB4142.EURPRD10.PROD.OUTLOOK.COM> (raw)
In-Reply-To: <20210316162237.877436-1-mark.jonas@de.bosch.com>
On 16 March 2021 16:23, 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>
Thanks for your efforts on this Mark.
prev parent reply other threads:[~2021-03-17 9:31 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
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 [this message]
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