linux-kernel - Re: [PATCH] ACPI: nfit: adjust annotation for why return 0 if fail to find NFIT at startup

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Date:   Tue, 7 Aug 2018 19:25:15 +0000
From:   "Verma, Vishal L" <vishal.l.verma@...el.com>
To:     "Williams, Dan J" <dan.j.williams@...el.com>,
        "ross.zwisler@...ux.intel.com" <ross.zwisler@...ux.intel.com>,
        "oceanhehy@...il.com" <oceanhehy@...il.com>,
        "lenb@...nel.org" <lenb@...nel.org>,
        "rjw@...ysocki.net" <rjw@...ysocki.net>
CC:     "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        "Jiang, Dave" <dave.jiang@...el.com>,
        "linux-nvdimm@...ts.01.org" <linux-nvdimm@...ts.01.org>,
        "linux-acpi@...r.kernel.org" <linux-acpi@...r.kernel.org>,
        "hehy1@...ovo.com" <hehy1@...ovo.com>
Subject: Re: [PATCH] ACPI: nfit: adjust annotation for why return 0 if fail
 to find NFIT at startup


On Tue, 2018-08-07 at 02:15 -0400, Ocean He wrote:
> From: Ocean He <hehy1@...ovo.com>

Just some minor nits in commit message wording:

> 
> Add detail explanation why it's ok to return 0 if fail to find NFIT at
      detailed          ^for                       ^we          ^an
> startup, refer to chapter 9.20.2 NVDIMM Root Device in ACPI 6.2 spec.
         . Refer

Perhaps Dave can fixup while applying..
> 
> Signed-off-by: Ocean He <hehy1@...ovo.com>
> ---
> v1: https://lists.01.org/pipermail/linux-nvdimm/2018-August/017311.html 
> v2: Per Vishal's comments of v1, it turns out that it's right to keep 
> "return 0" if NFIT not found at boot time. This v2 adjust annotation
> to avoid misunderstanding of "return 0".

Looks good, thanks for the update. Feel free to add:
Reviewed-by: Vishal Verma <vishal.l.verma@...el.com>

> 
>  drivers/acpi/nfit/core.c | 8 +++++++-
>  1 file changed, 7 insertions(+), 1 deletion(-)
> 
> diff --git a/drivers/acpi/nfit/core.c b/drivers/acpi/nfit/core.c
> index 7c47900..1b982fe 100644
> --- a/drivers/acpi/nfit/core.c
> +++ b/drivers/acpi/nfit/core.c
> @@ -3353,7 +3353,13 @@ static int acpi_nfit_add(struct acpi_device *adev)
>  
>  	status = acpi_get_table(ACPI_SIG_NFIT, 0, &tbl);
>  	if (ACPI_FAILURE(status)) {
> -		/* This is ok, we could have an nvdimm hotplugged later */
> +		/* The NVDIMM root device allows OS to trigger enumeration of
> +		 * NVDIMMs through NFIT at boot time and re-enumeration at
> +		 * root level via the _FIT method during runtime.
> +		 * This is ok to return 0 here, we could have an nvdimm
> +		 * hotplugged later and evaluate _FIT method which returns
> +		 * data in the format of a series of NFIT Structures.
> +		 */
>  		dev_dbg(dev, "failed to find NFIT at startup\n");
>  		return 0;
>  	}