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

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Date:   Fri, 26 Aug 2016 18:26:19 +0000
From:   "Kani, Toshimitsu" <toshi.kani@....com>
To:     "dan.j.williams@...el.com" <dan.j.williams@...el.com>,
        "linux-nvdimm@...ts.01.org" <linux-nvdimm@...ts.01.org>
CC:     "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.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 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.

Thanks,
-Toshi