linux-kernel - Re: [PATCH] hwmon: (acpi_power_meter) Install IPMI handler for Dell systems

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Date: Fri, 22 Dec 2023 13:08:11 +0100
From: Armin Wolf <W_Armin@....de>
To: Kai-Heng Feng <kai.heng.feng@...onical.com>,
 Guenter Roeck <linux@...ck-us.net>
Cc: jdelvare@...e.com, linux-hwmon@...r.kernel.org,
 linux-kernel@...r.kernel.org
Subject: Re: [PATCH] hwmon: (acpi_power_meter) Install IPMI handler for Dell
 systems

Am 22.12.23 um 04:57 schrieb Kai-Heng Feng:

> Hi Guenter,
>
> On Thu, Dec 21, 2023 at 7:49 AM Guenter Roeck <linux@...ck-us.net> 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] (00000000ab9e62c5) [IPMI] (20230628/evregion-130)
>>> [    3.717928] ACPI Error: Region IPMI (ID=7) has no handler (20230628/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 previous error (AE_NOT_EXIST) (20230628/psparse-529)
>>> [    3.717949] ACPI Error: Aborting method \_SB.PMI0._PMC due to previous 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 in
>>> IPMI region [0], so request module 'ipmi_si' which will load 'acpi_ipmi'
>>> 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-messages-displayed-in-dmesg?guid=guid-0d5ae482-1977-42cf-b417-3ed5c3f5ee62
>>>
>>> Signed-off-by: Kai-Heng Feng <kai.heng.feng@...onical.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_power_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 = 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 hacks
>> 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 device,
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 = read_capabilities(resource);
>>>        if (res)
>>> --
>>> 2.34.1
>>>