From: Wolfram Sang <wsa@the-dreams.de>
To: Xudong Chen <xudong.chen@mediatek.com>
Cc: Mark Rutland <mark.rutland@arm.com>,
arm@kernel.org, Matthias Brugger <matthias.bgg@gmail.com>,
srv_heupstream@mediatek.com, Sascha Hauer <kernel@pengutronix.de>,
Rob Herring <robh+dt@kernel.org>, Pawel Moll <pawel.moll@arm.com>,
Ian Campbell <ijc+devicetree@hellion.org.uk>,
Kumar Gala <galak@codeaurora.org>,
Russell King <linux@arm.linux.org.uk>,
Grant Likely <grant.likely@linaro.org>,
Jean Delvare <jdelvare@suse.de>, Arnd Bergmann <arnd@arndb.de>,
devicetree@vger.kernel.org, linux-kernel@vger.kernel.org,
linux-arm-kernel@lists.infradead.org, linux-i2c@vger.kernel.org,
Yingjoe Chen <yingjoe.chen@mediatek.com>,
Eddie Huang <eddie.huang@mediatek.com>,
Nathan Chung <nathan.chung@mediatek.com>,
YH Chen <yh.chen@mediatek.com>
Subject: Re: [PATCH v2 0/3] ARM: mediatek: Add driver for Mediatek I2C controller
Date: Thu, 13 Nov 2014 19:31:22 +0100 [thread overview]
Message-ID: <20141113183122.GH1275@katana> (raw)
In-Reply-To: <1415078977-18374-1-git-send-email-xudong.chen@mediatek.com>
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> MTK I2C HW has some limitation.
> 1. If the i2c_msg number is more than one, STOP will be issued instead of
> RS(Repeat Start) between each message.
>
> 2. Mediatek I2C controller support WRRD(write then read) mode, in WRRD
> mode the Repeat Start will be issued between 2 messages.
> In this driver if 2 messages is first write then read, the driver will
> combine 2 messages using Write-Read mode so the RS will be issued between
> the 2 messages.
> Ex: W/R/R, driver will combine first W/R and then R.
>
> 3. Due to HW limitation, in this version the max transfer data length is 255
> in one message.
This looks to me more like an SMBUS controller instead of I2C. Maybe you
should populate smbus_xfer rather than master_xfer?
> MT8135 and MT6589 can control I2C pins on PMIC(MT6397) by setting the i2c
> registers in MT8135 side.
I still didn't get this, even after reading the mail thread of old
series. Can someone maybe draw me a nice ASCII picture showing the setup
which is going on here?
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next prev parent reply other threads:[~2014-11-13 18:30 UTC|newest]
Thread overview: 11+ messages / expand[flat|nested] mbox.gz Atom feed top
2014-11-04 5:29 [PATCH v2 0/3] ARM: mediatek: Add driver for Mediatek I2C controller Xudong Chen
2014-11-04 5:29 ` [PATCH v2 1/3] dt-bindings: Add I2C bindings for mt65xx/mt81xx Xudong Chen
2014-11-13 18:16 ` Wolfram Sang
2014-11-14 3:13 ` xudong chen
2014-11-04 5:29 ` [PATCH v2 2/3] ARM: mediatek: Add I2C node for mt8135 and mt8127 Xudong Chen
2014-11-04 5:29 ` [PATCH v2 3/3] I2C: mediatek: Add driver for MediaTek I2C controller Xudong Chen
2014-11-13 2:08 ` [PATCH v2 0/3] ARM: mediatek: Add driver for Mediatek " xudong chen
2014-11-13 18:31 ` Wolfram Sang [this message]
2014-11-14 3:12 ` xudong chen
2014-11-14 8:00 ` Yingjoe Chen
2014-11-18 10:07 ` xudong chen
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