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From:   Akinobu Mita <akinobu.mita@gmail.com>
Date:   Thu, 31 Oct 2019 22:46:46 +0900
Message-ID: <CAC5umyg-QAvyKdSYQnVdST=p7CAGCQjmWpfc=rnK3dau36Y+mg@mail.gmail.com>
Subject: Re: [PATCH v2] nvme: Add hardware monitoring support
To:     Christoph Hellwig <hch@lst.de>
Cc:     Guenter Roeck <linux@roeck-us.net>,
        Keith Busch <kbusch@kernel.org>, Jens Axboe <axboe@fb.com>,
        Sagi Grimberg <sagi@grimberg.me>,
        LKML <linux-kernel@vger.kernel.org>,
        linux-nvme@lists.infradead.org,
        Linux PM <linux-pm@vger.kernel.org>,
        Chris Healy <cphealy@gmail.com>
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2019=E5=B9=B410=E6=9C=8830=E6=97=A5(=E6=B0=B4) 23:05 Christoph Hellwig <hch=
@lst.de>:
>
> On Wed, Oct 30, 2019 at 08:16:48PM +0900, Akinobu Mita wrote:
> > The nvme_init_identify() can be called multiple time in nvme ctrl's
> > lifetime (e.g 'nvme reset /dev/nvme*' or suspend/resume paths), so
> > should we need to prevent nvme_hwmon_init() from registering hwmon
> > device more than twice?
> >
> > In the nvme thermal zone patchset[1], thernal zone is registered in
> > nvme_init_identify and unregistered in nvme_stop_ctrl().
>
> So Guenter said above the thermal subsystem could use the information
> from hwmon as well.  Does this mean this patch would solve your needs
> as well?

The main reason I chose thermal framework was to utilize the temperature
threshold feature for notification on crossing a trip point temperature
without polling for smart log.

But the device I used for testing doesn't seem to report asynchronous
event immediately, so I'm not fully sure that's useful for now.

I have no problem with this nvme hwmon patch.  Maybe we can integrate
the temperature threshold feature into the nvme hwmon afterward.