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Subject: Re: [PATCH v10 5/7] i2c: fsi: Add transfer implementation
To:     Wolfram Sang <wsa@the-dreams.de>
Cc:     linux-i2c@vger.kernel.org, linux-kernel@vger.kernel.org,
        devicetree@vger.kernel.org, robh+dt@kernel.org,
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        andy.shevchenko@gmail.com, peda@axentia.se
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From:   Eddie James <eajames@linux.vnet.ibm.com>
Date:   Thu, 5 Jul 2018 13:52:13 -0500
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On 07/02/2018 01:24 PM, Wolfram Sang wrote:
>>>> +	if (msg->flags & I2C_M_RD)
>>>> +		cmd |= I2C_CMD_READ;
>>> Since you support MANGLING, I'd think you can easily support
>>> I2C_M_REV_DIR_ADDR here, too?
>> Hm, I don't really understand the purpose of that flag. From the docs:
>>
>> This toggles the Rd/Wr flag. That is, if you want to do a write, but
>>      need to emit an Rd instead of a Wr, or vice versa, you set this
>>      flag. For example:
>> S Addr Rd [A] Data [A] Data [A] ... [A] Data [A] P
>>
>> I don't think our hardware supports this type of operation.
> I'd think something like this should do:
>
> 	if (msg->flags & I2C_M_REV_DIR_ADDR)
> 		cmd ^= I2C_CMD_READ;

I meant that the hardware cannot interpret this, it would be a 
meaningless command unfortunately.

>