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

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Date:	Tue, 3 Feb 2015 16:09:28 +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 Tue, Feb 03, 2015 at 06:21:45AM -0800, Guenter Roeck wrote:
> On 02/03/2015 03:42 AM, Mark Brown wrote:

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

> Thinking about it, we should actually reject requests for _NATIVE. SMBus
> 16 bit accesses are either little endian or big endian.

Yes, that makes sense.  It's also hard to see a use case for _NATIVE and
smbus.

> >>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.

> Ah, guess I got confused. The SMBus accesses are already using reg_read
> and reg_write.

It's also possible that you've spotted some bug, wouldn't be the first
time.  Was this spotted by code inspection or by running into a problem?

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