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

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Message-ID: <b3f7a353-7d04-bdb9-0d68-176c38a0b9a3@caviumnetworks.com>
Date:   Tue, 27 Feb 2018 15:02:01 +0530
From:   George Cherian <gcherian@...iumnetworks.com>
To:     Wolfram Sang <wsa@...-dreams.de>
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

Hi Wolfram,

On 02/27/2018 02:34 PM, Wolfram Sang wrote:
> 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?
Yes, Thanks for the clarification. You are right It is better to
check before next message. I will make required changes and post the patch.
>

Regards
-George