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Date: Fri, 22 Dec 2023 13:08:11 +0100
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Subject: Re: [PATCH] hwmon: (acpi_power_meter) Install IPMI handler for Dell
 systems
To: Kai-Heng Feng <kai.heng.feng@canonical.com>,
 Guenter Roeck <linux@roeck-us.net>
Cc: jdelvare@suse.com, linux-hwmon@vger.kernel.org,
 linux-kernel@vger.kernel.org
References: <20231220051350.392350-1-kai.heng.feng@canonical.com>
 <5a81eda0-5044-4088-9aba-cf725e6fca9a@roeck-us.net>
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From: Armin Wolf <W_Armin@gmx.de>
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Am 22.12.23 um 04:57 schrieb Kai-Heng Feng:

> Hi Guenter,
>
> On Thu, Dec 21, 2023 at 7:49=E2=80=AFAM Guenter Roeck <linux@roeck-us.ne=
t> wrote:
>> On Wed, Dec 20, 2023 at 01:13:50PM +0800, Kai-Heng Feng wrote:
>>> The following error can be observed at boot:
>>> [    3.717920] ACPI Error: No handler for Region [SYSI] (00000000ab9e6=
2c5) [IPMI] (20230628/evregion-130)
>>> [    3.717928] ACPI Error: Region IPMI (ID=3D7) has no handler (202306=
28/exfldio-261)
>>>
>>> [    3.717936] No Local Variables are initialized for Method [_GHL]
>>>
>>> [    3.717938] No Arguments are initialized for method [_GHL]
>>>
>>> [    3.717940] ACPI Error: Aborting method \_SB.PMI0._GHL due to previ=
ous error (AE_NOT_EXIST) (20230628/psparse-529)
>>> [    3.717949] ACPI Error: Aborting method \_SB.PMI0._PMC due to previ=
ous error (AE_NOT_EXIST) (20230628/psparse-529)
>>> [    3.717957] ACPI: \_SB_.PMI0: _PMC evaluation failed: AE_NOT_EXIST
>>>
>>> On Dell systems several methods of acpi_power_meter access variables i=
n
>>> IPMI region [0], so request module 'ipmi_si' which will load 'acpi_ipm=
i'
>>> and install the region handler accordingly.
>>>
>>> [0] https://www.dell.com/support/manuals/en-us/redhat-enterprise-linux=
-v8.0/rhel8_rn_pub/advanced-configuration-and-power-interface-acpi-error-m=
essages-displayed-in-dmesg?guid=3Dguid-0d5ae482-1977-42cf-b417-3ed5c3f5ee6=
2
>>>
>>> Signed-off-by: Kai-Heng Feng <kai.heng.feng@canonical.com>
>>> ---
>>>   drivers/hwmon/acpi_power_meter.c | 2 ++
>>>   1 file changed, 2 insertions(+)
>>>
>>> diff --git a/drivers/hwmon/acpi_power_meter.c b/drivers/hwmon/acpi_pow=
er_meter.c
>>> index 703666b95bf4..b9db53166bc9 100644
>>> --- a/drivers/hwmon/acpi_power_meter.c
>>> +++ b/drivers/hwmon/acpi_power_meter.c
>>> @@ -882,6 +882,8 @@ static int acpi_power_meter_add(struct acpi_device=
 *device)
>>>        strcpy(acpi_device_name(device), ACPI_POWER_METER_DEVICE_NAME);
>>>        strcpy(acpi_device_class(device), ACPI_POWER_METER_CLASS);
>>>        device->driver_data =3D resource;
>>> +     if (dmi_match(DMI_SYS_VENDOR, "Dell Inc."))
>>> +             request_module("ipmi_si");
>>>
>> This looks like a terrible hack to me. Is there precedent of similar ha=
cks
>> elsewhere showing that this is the "way to go" ?
> Yes it's ugly.
>
> The error happens in the ACPI ASL code, so it's not possible to know
> if any method of apci_power_meter requires IPMI region.
> I really can't think of any better solution for it.
>
> Kai-Heng

Maybe we could use an ACPI scan handler for that?
Basically we would call request_module() upon discovering an ACPI IPMI dev=
ice,
so that the necessary module is available for handling the IPMI opregion.
This would also prevent any issues should other devices also require IPMI =
access.

Armin Wolf

>> Guenter
>>
>>>        res =3D read_capabilities(resource);
>>>        if (res)
>>> --
>>> 2.34.1
>>>