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From:   Andrey Smirnov <andrew.smirnov@gmail.com>
Date:   Thu, 23 May 2019 19:48:56 -0700
Message-ID: <CAHQ1cqG-cb=1hyO8oeV4k-6Pq4q+aqhH8RPx04i2oPTNhAhiVg@mail.gmail.com>
Subject: Re: [PATCH] thermal/drivers/of: Add a get_temp_id callback function
To:     Daniel Lezcano <daniel.lezcano@linaro.org>
Cc:     Eduardo Valentin <edubezval@gmail.com>,
        Zhang Rui <rui.zhang@intel.com>,
        linux-kernel <linux-kernel@vger.kernel.org>,
        Linux PM list <linux-pm@vger.kernel.org>,
        Chris Healy <cphealy@gmail.com>
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On Mon, Apr 29, 2019 at 9:51 AM Daniel Lezcano
<daniel.lezcano@linaro.org> wrote:
>
> On 24/04/2019 01:08, Daniel Lezcano wrote:
> > On 23/04/2019 17:44, Eduardo Valentin wrote:
> >> Hello,
> >>
> >> On Tue, Apr 16, 2019 at 07:22:03PM +0200, Daniel Lezcano wrote:
> >>> Currently when we register a sensor, we specify the sensor id and a data
> >>> pointer to be passed when the get_temp function is called. However the
> >>> sensor_id is not passed to the get_temp callback forcing the driver to
> >>> do extra allocation and adding back pointer to find out from the sensor
> >>> information the driver data and then back to the sensor id.
> >>>
> >>> Add a new callback get_temp_id() which will be called if set. It will
> >>> call the get_temp_id() with the sensor id.
> >>>
> >>> That will be more consistent with the registering function.
> >>
> >> I still do not understand why we need to have a get_id callback.
> >> The use cases I have seen so far, which I have been intentionally rejecting, are
> >> mainly solvable by creating other compatible entries. And really, if you
> >> have, say a bandgap, chip that supports multiple sensors, but on
> >> SoC version A it has 5 sensors, and on SoC version B it has only 4,
> >> or on SoC version C, it has 5 but they are either logially located
> >> in different places (gpu vs iva regions), these are all cases in which
> >> you want a different compatible!
> >>
> >> Do you mind sharing why you need a get sensor id callback?
> >
> > It is not a get sensor id callback, it is a get_temp callback which pass
> > the sensor id.
> >
> > See in the different drivers, it is a common pattern there is a
> > structure for the driver, then a structure for the sensor. When the
> > get_temp is called, the callback needs info from the sensor structure
> > and from the driver structure, so a back pointer to the driver structure
> > is added in the sensor structure.
>
> Hi Eduardo,
>
> does the explanation clarifies the purpose of this change?
>

Eduardo, did you ever have a chance to revisit this thread? I would
really like to make some progress on this one to unblock my i.MX8MQ
hwmon series.

Thanks,
Andrey Smirnov