linux-kernel - Re: [PATCH 3/3] libnvdimm: New ACPI 6.2 DSM functions

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Date:   Fri, 9 Jun 2017 10:13:51 -0700
From:   Dan Williams <dan.j.williams@...el.com>
To:     Jerry Hoemann <Jerry.Hoemann@....com>
Cc:     Johannes Thumshirn <jthumshirn@...e.de>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        "linux-nvdimm@...ts.01.org" <linux-nvdimm@...ts.01.org>
Subject: Re: [PATCH 3/3] libnvdimm: New ACPI 6.2 DSM functions

On Fri, Jun 9, 2017 at 9:59 AM, Jerry Hoemann <jerry.hoemann@....com> wrote:
> On Thu, Jun 08, 2017 at 10:28:51PM -0700, Dan Williams wrote:
>> On Thu, Jun 8, 2017 at 1:02 AM, Johannes Thumshirn <jthumshirn@...e.de> wrote:
>> > On 06/07/2017 07:04 PM, Jerry Hoemann wrote:
>> >> @@ -179,6 +217,10 @@ static inline const char *nvdimm_bus_cmd_name(unsigned cmd)
>> >>               [ND_CMD_ARS_START] = "ars_start",
>> >>               [ND_CMD_ARS_STATUS] = "ars_status",
>> >>               [ND_CMD_CLEAR_ERROR] = "clear_error",
>> >> +             [5] = "trans_spa",
>> >> +             [7] = "ars_err_inj",
>> >> +             [8] = "ars_err_inj_clr",
>> >> +             [9] = "ars_err_inj_stat",
>> >>               [ND_CMD_CALL] = "cmd_call",
>> >>       };
>> >
>> > Can you please add the new values to the enum in uapi/ndctl.h? I don't
>> > really like the magic numbers here.
>>
>> I think the reason Jerry didn't add them is due to symmetry. All the
>> current ND_CMD_ definitions have corresponding ND_IOCTL_ definitions.
>> These new commands we're only adding function number support and using
>> ND_CMD_CALL for the ioctl transport.
>
>   Yes, this is correct.
>
>>                                       We can still add definitions for
>> them, but perhaps with an ACPI_NFIT_DSM_ prefix? The only consumer in
>> the kernel of this is debug output code. I think perhaps we should
>> just delete them here and either print raw numbers or enable
>> acpi_nfit_ctl() to the decode and not rely on nvdimm_bus_cmd_name()
>> which is meant to represent NVDIMM bus type generic command numbers.
>
> This also comes into play when doing:
>
>         cat /sys/class/nd/ndctl0/device/nd/ndctl0/device/commands
>
> Without change here the new functions would show up as "unknown unknown unknown unknown."
>
> Dan, are you suggesting I change the above to:
>
>                [ND_CMD_CLEAR_ERROR] = "clear_error",
>  +             [5] = "5",
>  +             [7] = "7",
>  +             [8] = "8",
>  +             [9] = "9",
>                [ND_CMD_CALL] = "cmd_call",
>
> Note, "6" is currently reserved by ACPI.  I could add that also.

I think it should behave the same as the dimm level 'cmd' vs 'func'
distinction. Where only the ND_CMD instances are enumerated in the
sysfs '/sys/bus/nd/devices/ndbus0/commands' attribute. The rest of the
supported functions are identified in the 'dsm_mask' attribute. We
don't currently have one of those for the bus level but we can add it
to "/sys/bus/nd/devices/ndbus0/nfit/dsm_mask". This would be similar
to "/sys/bus/nd/devices/nmem0/nfit/dsm_mask".