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Subject: Re: [PATCH] powernv: Add OCC driver to mmap sensor area
From: Benjamin Herrenschmidt <benh@au1.ibm.com>
Reply-To: benh@au1.ibm.com
To: Stewart Smith <stewart@linux.vnet.ibm.com>, Shilpasri G Bhat
 <shilpa.bhat@linux.vnet.ibm.com>, mpe@ellerman.id.au
Cc: ego@linux.vnet.ibm.com, linux-kernel@vger.kernel.org, paulus@samba.org,
 linuxppc-dev@lists.ozlabs.org, akshay.adiga@linux.vnet.ibm.com
Date: Mon, 02 Oct 2017 10:35:02 +0200
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On Mon, 2017-10-02 at 14:14 +1100, Stewart Smith wrote:
> Shilpasri G Bhat <shilpa.bhat@linux.vnet.ibm.com> writes:
> > This driver provides interface to mmap the OCC sensor area
> > to userspace to parse and read OCC inband sensors.
> 
> Why?
> 
> Is this for debug? If so, the existing exports interface should be used.
> 
> If there's actual sensors, we already have two ways of exposing sensors
> to Linux: the OPAL_SENSOR API and the IMC API.
> 
> Why this method and not use the existing ones?

More than that, a sensor should be exposed to userspace via hwmon, not
some random direct userspace map.

Ben.