linux-kernel - Re: [PATCH 4/4] i2c: xlp9xx: Check for Bus state after every transfer

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Message-ID: <20180227090416.gxgof6fyzdeshtmf@katana>
Date:   Tue, 27 Feb 2018 10:04:16 +0100
From:   Wolfram Sang <wsa@...-dreams.de>
To:     George Cherian <gcherian@...iumnetworks.com>
Cc:     George Cherian <george.cherian@...ium.com>,
        linux-kernel@...r.kernel.org, linux-i2c@...r.kernel.org
Subject: Re: [PATCH 4/4] i2c: xlp9xx: Check for Bus state after every transfer

On Tue, Feb 27, 2018 at 10:30:31AM +0530, George Cherian wrote:
> Hi Wolfram,
> 
> Thanks for the review.
> 
> On 02/27/2018 01:52 AM, Wolfram Sang wrote:
> > 
> > On Thu, Jan 18, 2018 at 05:39:24AM +0000, George Cherian wrote:
> > > I2C bus enters the STOP condition after the DATA_DONE interrupt is raised.
> > > Essentially the driver should be checking the bus state before sending
> > > the next transaction.
> > 
> > Yes.
> > 
> > > In case the next transaction is initiated while the
> > > bus is busy, the prior transactions stop condition is not achieved.
> > 
> > I didn't fully get why you can't check the BUSY bit and wait a little
> > just before you push out the next message?
> Yes, I am checking for the BUSY bit and looping.

Yes, but *after* the STOP, not *before* the next message. I haven't
fully understood why you don't do this before the next message is about
to be sent. That might save you some busy looping, or?


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