linux-kernel - Re: [PATCH] i2c: cadence: Added slave support

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Date:   Fri, 20 Dec 2019 14:55:05 +0530
From:   Shubhrajyoti Datta <shubhrajyoti.datta@...il.com>
To:     Radu Pirea <radu_nicolae.pirea@....ro>
Cc:     Wolfram Sang <wsa@...-dreams.de>,
        linux-arm-kernel <linux-arm-kernel@...ts.infradead.org>,
        linux-i2c <linux-i2c@...r.kernel.org>,
        linux-kernel <linux-kernel@...r.kernel.org>,
        Chirag Parekh <chirag.parekh@...inx.com>,
        Michal Simek <michal.simek@...inx.com>
Subject: Re: [PATCH] i2c: cadence: Added slave support

Hi ,

On Thu, Dec 19, 2019 at 7:00 PM Radu Pirea <radu_nicolae.pirea@....ro> wrote:
>
> On Thu, 2019-12-19 at 14:05 +0100, Wolfram Sang wrote:
> > > +/**
> > > + * enum cdns_i2c_mode - I2C Controller current operating mode
> > > + *
> > > + * @CDNS_I2C_MODE_SLAVE:       I2C controller operating in slave
> > > mode
> > > + * @CDNS_I2C_MODE_MASTER:      I2C Controller operating in master
> > > mode
> > > + */
> >
> > Can't the hardware operate as master and slave at the same time?
> >
>
> Of course, it can. If the driver has a slave registered wait and
> listens and if the subsystem needs to use the controller as master, the
> driver changes the state of the controller to master, sends and reads
> data from the bus and after this change the state of the controller to
> slave.

However that should be done only if no master is talking to the slave right?

> In cdns_i2c_master_xfer is done all the magic.