From: Wolfram Sang <wsa@kernel.org>
To: "Jonas Mark (BT-FIR/ENG1-Grb)" <Mark.Jonas@de.bosch.com>
Cc: Adam Thomson <Adam.Thomson.Opensource@diasemi.com>,
Support Opensource <Support.Opensource@diasemi.com>,
Lee Jones <lee.jones@linaro.org>,
Rob Herring <robh+dt@kernel.org>,
"devicetree@vger.kernel.org" <devicetree@vger.kernel.org>,
"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
"linux-i2c@vger.kernel.org" <linux-i2c@vger.kernel.org>,
Steve Twiss <stwiss.opensource@diasemi.com>,
"marek.vasut@gmail.com" <marek.vasut@gmail.com>,
"RUAN Tingquan (BT-FIR/ENG1-Zhu)" <Tingquan.Ruan@cn.bosch.com>,
"Streidl Hubert (BT-FIR/ENG1-Grb)" <Hubert.Streidl@de.bosch.com>,
"festevam@gmail.com" <festevam@gmail.com>,
"o.rempel@pengutronix.de" <o.rempel@pengutronix.de>,
"anson.huang@nxp.com" <anson.huang@nxp.com>
Subject: Re: [PATCH 1/1] mfd: da9063: Support SMBus and I2C mode
Date: Thu, 28 Jan 2021 21:53:11 +0100 [thread overview]
Message-ID: <20210128205311.GB3094@kunai> (raw)
In-Reply-To: <df52d5e7069541e78b8b01ddc54a6777@de.bosch.com>
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Hi,
> None of that seems to model the inability to perform atomic transactions
> within the SMBus timeout. This is either a bug of this specific driver
> or maybe the expressiveness of I2C_FUNC_* is not sufficient.
>
> https://elixir.bootlin.com/linux/latest/source/include/uapi/linux/i2c.h#L88
>
> What flag do you think we could check to find out whether the bus is
> able to obey the SMBus timeout or not?
While not perfect, you can reasonably assume that the bus cannot obey to
SMBus timings when I2C_FUNC_I2C is set. Because in the vast majority of
all cases with I2C_FUNC_I2C, SMBus commands are emulated which is prone
to the latency you described. You'd need a native SMBus controller to
avoid that which usually has not I2C_FUNC_I2C set.
Happy hacking,
Wolfram
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prev parent reply other threads:[~2021-01-28 20:54 UTC|newest]
Thread overview: 8+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-01-25 12:54 [PATCH 0/1] mfd: da9063: Support SMBus and I2C mode Mark Jonas
2021-01-25 12:54 ` [PATCH 1/1] " Mark Jonas
2021-01-25 18:49 ` Jonas Mark (BT-FIR/ENG1-Grb)
2021-01-25 18:58 ` Mark Jonas
2021-01-26 8:23 ` Lee Jones
2021-01-28 14:50 ` Adam Thomson
2021-01-28 16:09 ` AW: " Jonas Mark (BT-FIR/ENG1-Grb)
2021-01-28 20:53 ` Wolfram Sang [this message]
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