linux-kernel - Re: [PATCH] regmap: Fix i2c word access when using SMBus access functions

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Date:	Tue, 3 Feb 2015 11:42:10 +0000
From:	Mark Brown <broonie@...nel.org>
To:	Guenter Roeck <linux@...ck-us.net>
Cc:	Lars-Peter Clausen <lars@...afoo.de>,
	Robert Rosengren <robert.rosengren@...s.com>,
	linux-kernel@...r.kernel.org,
	Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
	Jean Delvare <jdelvare@...e.de>
Subject: Re: [PATCH] regmap: Fix i2c word access when using SMBus access
 functions

On Mon, Feb 02, 2015 at 06:30:02AM -0800, Guenter Roeck wrote:
> On 02/02/2015 03:56 AM, Mark Brown wrote:

> >Yes, we really ought to handle _NATIVE too (though the chances of it
> >being used with I2C are minimal, it's mostly for MMIO).  This also feels

> Well, we do; it is handled similar to the big endian case with the current
> code. Do you think it should be handled differently ? If yes, how ?

Perhaps it just needs to be more explicit about how it's handling native
endian?  I didn't spot it.

> >like it's something that should be being handled further up the stack in
> >the serialization code but given that there's direct functions for this
> >in the smbus code perhaps it's better here.  Or perhaps the smbus
> >support ought to be transitioned to use the bus interface and set
> >reg_write() and reg_read() operations now that we can do that, it seems
> >like a better fit though it might break compatibility with wierd devices.

> I thought about that, but since the smbus functions perform endianness
> conversion it would mean that I would have to undo that conversion just
> to have it done again.

No, the whole point is that by doing this you avoid any endianness
conversions or formatting in the framework at all so you can just use
the smbus functions to handle the formatting.

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