From mboxrd@z Thu Jan  1 00:00:00 1970
From: Joe Perches <joe-6d6DIl74uiNBDgjK7y7TUQ@public.gmane.org>
Subject: Re: [PATCH V1 1/1] iio: Added Capella cm3232 ambient light sensor
 driver.
Date: Mon, 05 Jan 2015 08:42:46 -0800
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To: Daniel Baluta <daniel.baluta-ral2JQCrhuEAvxtiuMwx3w@public.gmane.org>
Cc: Kevin Tsai <ktsai-GubuWUlQtMwciDkP5Hr2oA@public.gmane.org>, Wolfram Sang <wsa-z923LK4zBo2bacvFa/9K2g@public.gmane.org>, Rob Herring <robh+dt-DgEjT+Ai2ygdnm+yROfE0A@public.gmane.org>, Pawel Moll <pawel.moll-5wv7dgnIgG8@public.gmane.org>, Mark Rutland <mark.rutland-5wv7dgnIgG8@public.gmane.org>, Ian Campbell <ijc+devicetree-KcIKpvwj1kUDXYZnReoRVg@public.gmane.org>, Kumar Gala <galak-sgV2jX0FEOL9JmXXK+q4OQ@public.gmane.org>, Jonathan Cameron <jic23-DgEjT+Ai2ygdnm+yROfE0A@public.gmane.org>, Hartmut Knaack <knaack.h-Mmb7MZpHnFY@public.gmane.org>, Lars-Peter Clausen <lars-Qo5EllUWu/uELgA04lAiVw@public.gmane.org>, Peter Meerwald <pmeerw-jW+XmwGofnusTnJN9+BGXg@public.gmane.org>, Grant Likely <grant.likely-QSEj5FYQhm4dnm+yROfE0A@public.gmane.org>, Andrew Morton <akpm-de/tnXTf+JLsfHDXvbKv3WD2FQJk+8+b@public.gmane.org>, "David S. Miller" <davem-fT/PcQaiUtIeIZ0/mPfg9Q@public.gmane.org>, Greg Kroah-Hartman <gregkh-hQyY1W1yCW8ekmWlsbkhG0B+6BGkLq7r@public.gmane.org>, Mauro Carvalho Chehab <mchehab-JPH+aEBZ4P+UEJcrhfAQsw@public.gmane.org>, Antti Palosaari <crope-X3B1VOXEql0@public.gmane.org>, Archana Patni <archana.patni-VuQAYsv1563Yd54FQh9/CA@public.gmane.org>, linux-i2c-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, devicetree-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, "linux-iio-u79uwXL29TY76Z2rM5mHXA@public.gmane.org" <linux-iio-u79uwXL29TY76Z2rM5mHXA@public.gmane.org>, Linux Kernel Mailing List <linux-kernel-u79uwXL29TY76Z2rM5mHXA@public.gmane.org>
List-Id: devicetree@vger.kernel.org

On Mon, 2015-01-05 at 16:20 +0200, Daniel Baluta wrote:
> On Mon, Jan 5, 2015 at 3:09 PM, Joe Perches <joe-6d6DIl74uiNBDgjK7y7TUQ@public.gmane.org> wrote:
> > On Mon, 2015-01-05 at 12:51 +0200, Daniel Baluta wrote:
> >> On Thu, Jan 1, 2015 at 2:10 AM, Kevin Tsai <ktsai-GubuWUlQtMwciDkP5Hr2oA@public.gmane.org> wrote:
> >> > CM3232 is an advanced ambient light sensor with I2C protocol interface.
> >> > The I2C slave address is internally hardwired as 0x10 (7-bit).  Writing
> >> > to configure register is byte mode, but reading ALS register requests to
> >> > use word mode for 16-bit resolution.
[]
> >> You could directly return i2c_smbus_write_byte_data(..).
> >
> > Sometimes it's better to return a specific value
> > for the error instead of depending on correctness
> > of all the indirect functions in the call chain.
> >
> > In this case, all the smbus_xfer functions must
> > return 0 on success.  Do they?
> 
> Yes.
> 
> http://lxr.free-electrons.com/source/drivers/i2c/i2c-core.c#L2845

This doesn't show that adapter->algo->smbus_xfer()
returns 0, you have to look at the code for that
indirectly called function. 

> Also, I guess kbuild test robot will complain about it, like here:
> 
> http://marc.info/?l=linux-kernel&m=141963536230419&w=2

Is the kbuild test robot now submitting patches for all
possible coccinelle simplifications?  I don't think so.