linux-kernel - Re: [PATCH 2/3] acpi, nfit: add dimm device notification support

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Message-ID: <1472509138.1532.61.camel@hpe.com>
Date:   Mon, 29 Aug 2016 22:19:40 +0000
From:   "Kani, Toshimitsu" <toshi.kani@....com>
To:     "dan.j.williams@...el.com" <dan.j.williams@...el.com>
CC:     "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        "linux-nvdimm@...ts.01.org" <linux-nvdimm@...ts.01.org>,
        "linux-acpi@...r.kernel.org" <linux-acpi@...r.kernel.org>,
        "rafael.j.wysocki@...el.com" <rafael.j.wysocki@...el.com>
Subject: Re: [PATCH 2/3] acpi, nfit: add dimm device notification support

On Fri, 2016-08-26 at 11:39 -0700, Dan Williams wrote:
> On Fri, Aug 26, 2016 at 11:26 AM, Kani, Toshimitsu <toshi.kani@....co
> m> wrote:
> > 
> > On Tue, 2016-08-23 at 14:54 -0700, Dan Williams wrote:
> > > 
> > > Per "ACPI 6.1 Section 9.20.3" NVDIMM devices, children of the
> > > ACPI0012 NVDIMM Root device, can receive health event
> > > notifications.
> > > 
> > > Given that these devices are precluded from registering a
> > > notification handler via acpi_driver.acpi_device_ops (due to no
> > > _HID), we use acpi_install_notify_handler() directly.
> > 
> > I've confirmed that this ACPI notify handler is called properly.
> > 
> > > 
> > > The registered handler, acpi_nvdimm_notify(), triggers a poll(2)
> > > event on the nmemX/nfit/flags sysfs attribute when a health event
> > > notification is received.
> > 
> > This sounds good idea, but should we document that the value of
> > sysfs 'flags' itself does not get updated?  User space program will
> > then need to call its _DSM to get health status.
> 
> Yes, this plus the new scrub attribute behavior need documentation.
> I'll prepare a refresh for Documentation/nvdimm/nvdimm.txt.
>
> The need to call a _DSM after a notification event is documented in
> the ACPI spec, but you're right, we do need to connect that language
> to the Linux specific mechanism.

Sounds great.  With that:

Reviewed-by: Toshi Kani <toshi.kani@....com>

Thanks!
-Toshi