Re: [PATCH V2] input:ad7879-i2c use swapped varient of i2c_smbus_read_word_data

[Dmitry Torokhov <dmitry.torokhov@gmail.com>]

On Fri, Oct 21, 2011 at 05:14:45PM +0100, Jonathan Cameron wrote:
> On 10/21/11 17:09, Dmitry Torokhov wrote:
> > On Fri, Oct 21, 2011 at 12:57:16PM +0100, Jonathan Cameron wrote:
> >> This varient was introduced in
> >> i2c: boilerplate function for byte swapped smbus_write/read_word_data
> >>
> >> This also has the side effect of ensuring any errors from the i2c
> >> read and no longer mangled.
> >>
> >> Signed-off-by: Jonathan Cameron <jic23@cam.ac.uk>
> >> ---
> >> V2: include the write function as pointed out by Michael Hennerich.
> >>
> >> The patch introducing this swapped function is working its way through the i2c
> >> tree.
> >>
> >>  drivers/input/touchscreen/ad7879-i2c.c |    4 ++--
> >>  1 files changed, 2 insertions(+), 2 deletions(-)
> >>
> >> diff --git a/drivers/input/touchscreen/ad7879-i2c.c b/drivers/input/touchscreen/ad7879-i2c.c
> >> index 4e4e58c..cc51392 100644
> >> --- a/drivers/input/touchscreen/ad7879-i2c.c
> >> +++ b/drivers/input/touchscreen/ad7879-i2c.c
> >> @@ -47,7 +47,7 @@ static int ad7879_i2c_read(struct device *dev, u8 reg)
> >>  {
> >>  	struct i2c_client *client = to_i2c_client(dev);
> >>  
> >> -	return swab16(i2c_smbus_read_word_data(client, reg));
> >> +	return i2c_smbus_read_word_swapped(client, reg);
> > 
> > This is still not endian-safe. I wonder if introducing
> > i2c_smbus_read_word_swapped() just makes the metter worse by hiding
> > this...
> > 
> > I'd prefer if we had i2c_smbus_read_be16() instead.
> smbus spec says that all transfers must be little endian.
> Hence it is type safe because the smbus controllers are guaranteed to have made
> that assumption and converted to cpu endianess.  If not they are buggy.
> Hence, this is endian safe.

Ah, right... OK then.

-- 
Dmitry