linux-kernel - RE: [EXT] Re: i2c: imx: support slave mode for imx I2C driver

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Message-ID: <DB7PR04MB44909B080A8C8D53416F34058FD30@DB7PR04MB4490.eurprd04.prod.outlook.com>
Date:   Mon, 12 Aug 2019 04:22:03 +0000
From:   Biwen Li <biwen.li@....com>
To:     Wolfram Sang <wsa@...-dreams.de>, Leo Li <leoyang.li@....com>
CC:     Joshua Frkuska <joshua_frkuska@...tor.com>,
        "shawnguo@...nel.org" <shawnguo@...nel.org>,
        "s.hauer@...gutronix.de" <s.hauer@...gutronix.de>,
        "kernel@...gutronix.de" <kernel@...gutronix.de>,
        "festevam@...il.com" <festevam@...il.com>,
        dl-linux-imx <linux-imx@....com>,
        "linux-i2c@...r.kernel.org" <linux-i2c@...r.kernel.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        "linux-arm-kernel@...ts.infradead.org" 
        <linux-arm-kernel@...ts.infradead.org>,
        Laurentiu Tudor <laurentiu.tudor@....com>
Subject: RE: [EXT] Re: i2c: imx: support slave mode for imx I2C driver

> On Fri, Aug 09, 2019 at 03:18:01AM +0000, Biwen Li wrote:
> > > > The patch supports slave mode for imx I2C driver
> > > >
> > > > Signed-off-by: Biwen Li <biwen.li@....com>
> > >
> > > Wow, this is much simpler than the other approach flying around:
> > >
> > > http://patchwork.ozlabs.org/patch/1124048/
> > >
> > > Can this one be master and slave on the same bus, too?
> > At the same time, the same bus is in master mode or slave mode.
> 
> So, can someone kindly point out the key differences to me?
The I2C module cannot be a master and a slave simultaneously.
Such as: if the i2c module is used in slave mode with command
'echo slave-24c02 0x64 > /sys/bus/i2c/devices/i2c-0/new_device',
At the mean time, you cannot do master operations(i2cset/i2cget). 
You can switch mode from slave to master with command 'echo 0x64
 > /sys/bus/i2c/devices/i2c-0/delete_device', then you can do master
operations.

Adding Leo to this version too.