From mboxrd@z Thu Jan 1 00:00:00 1970 From: wsa@the-dreams.de (Wolfram Sang) Date: Thu, 13 Nov 2014 19:31:22 +0100 Subject: [PATCH v2 0/3] ARM: mediatek: Add driver for Mediatek I2C controller In-Reply-To: <1415078977-18374-1-git-send-email-xudong.chen@mediatek.com> References: <1415078977-18374-1-git-send-email-xudong.chen@mediatek.com> Message-ID: <20141113183122.GH1275@katana> To: linux-arm-kernel@lists.infradead.org List-Id: linux-arm-kernel.lists.infradead.org > 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? -------------- next part -------------- A non-text attachment was scrubbed... Name: signature.asc Type: application/pgp-signature Size: 819 bytes Desc: Digital signature URL: