Received-SPF: pass (google.com: best guess record for domain of linux-kernel-owner@vger.kernel.org designates 209.132.180.67 as permitted sender) client-ip=209.132.180.67;
Date:   Mon, 17 Sep 2018 11:06:12 +0100
From:   Jonathan Cameron <jonathan.cameron@huawei.com>
To:     Michal Simek <michal.simek@xilinx.com>
CC:     Jonathan Cameron <jic23@kernel.org>,
        Manish Narani <manish.narani@xilinx.com>, <knaack.h@gmx.de>,
        <lars@metafoo.de>, <pmeerw@pmeerw.net>, <robh+dt@kernel.org>,
        <mark.rutland@arm.com>, <sudeep.holla@arm.com>,
        <amit.kucheria@linaro.org>, <leoyang.li@nxp.com>,
        <broonie@kernel.org>, <arnaud.pouliquen@st.com>,
        <eugen.hristev@microchip.com>, <rdunlap@infradead.org>,
        <geert@linux-m68k.org>, <ak@it-klinger.de>,
        <freeman.liu@spreadtrum.com>, <lukas@wunner.de>,
        <vilhelm.gray@gmail.com>, <gregkh@linuxfoundation.org>,
        <kstewart@linuxfoundation.org>, <sgoud@xilinx.com>,
        <anirudh@xilinx.com>, <linux-iio@vger.kernel.org>,
        <linux-arm-kernel@lists.infradead.org>,
        <linux-kernel@vger.kernel.org>, <devicetree@vger.kernel.org>
Subject: Re: [PATCH v2 2/4] iio: Documentation: Add Xilinx AMS sysfs
 documentation
Message-ID: <20180917110215.00002846@huawei.com>
In-Reply-To: <cf2acc8a-ed2d-27f4-ca58-3e2132e17d2a@xilinx.com>
References: <1536909510-7166-1-git-send-email-manish.narani@xilinx.com>
        <1536909510-7166-3-git-send-email-manish.narani@xilinx.com>
        <20180916111242.73af71ed@archlinux>
        <cf2acc8a-ed2d-27f4-ca58-3e2132e17d2a@xilinx.com>
Organization: Huawei
MIME-Version: 1.0
Content-Type: text/plain; charset="US-ASCII"
Content-Transfer-Encoding: 7bit
Sender: linux-kernel-owner@vger.kernel.org
Precedence: bulk

On Mon, 17 Sep 2018 11:56:08 +0200
Michal Simek <michal.simek@xilinx.com> wrote:

> On 16.9.2018 12:12, Jonathan Cameron wrote:
> > On Fri, 14 Sep 2018 12:48:28 +0530
> > Manish Narani <manish.narani@xilinx.com> wrote:
> >   
> >> Add documentation for xilinx-ams driver. This contains information about
> >> various voltages and temperatures on PS (Processing System), PL
> >> (Programmable Logic) and AMS Control Block.
> >>
> >> Signed-off-by: Manish Narani <manish.narani@xilinx.com>  
> > The more I look at this device the more I'm convinced it is very much a dedicated
> > hardware monitoring function, not a generic ADC sensing unit at all.
> > 
> > Hmm.  It is still fine to have it in IIO but you need to think in detail
> > about how you are going to interface this to hwmon via the iio-hwmon bridge.
> > 
> > Some of the interface complexity should only really be apparent when we hit
> > hwmon perhaps rather than having so many different custom interfaces in IIO.
> > 
> > Please also loop in the maintainers and lists for hwmon in the next
> > version so we can get their input.  
> 
> Isn't there iio-hwmon driver for this?
> 
> Thanks,
> Michal

Absolutely.  The interesting bit is that if we are planning to actually expose
the many monitoring channels via iio-hwmon IIRC it won't use the extended names
at all (I may have missremembered this thogh).  As such we may want to reduced
the amount of custom ABI in IIO in favour of a level of opaqueness with the
'real' interface provided by the iio-hwmon bridge driver.  A quick glance
suggested we may need to increase the information exposed by the iio-hwmon
driver to make this work.

When we have run into cases like this (a very much hardware monitoring oriented
device with a few general purpose channels) in the past we have always gotten
agreement from the hwmon maintainers that they are happy with using an IIO provider
and the iio-hwmon driver route. It is just nice to keep everyone in agreement
and have no surprises!

Jonathan