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Sender: Guenter Roeck <groeck7@gmail.com>
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Date: Mon, 25 Mar 2024 07:40:03 -0700
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Subject: Re: [PATCH v5 2/2] hwmon: (acpi_power_meter) Ensure IPMI space
 handler is ready on Dell systems
Content-Language: en-US
To: Andy Shevchenko <andy@black.fi.intel.com>,
 Kai-Heng Feng <kai.heng.feng@canonical.com>
Cc: rafael@kernel.org, lenb@kernel.org, jdelvare@suse.com,
 robert.moore@intel.com, linux-acpi@vger.kernel.org,
 linux-kernel@vger.kernel.org, linux-hwmon@vger.kernel.org,
 acpica-devel@lists.linux.dev
References: <20240320084317.366853-1-kai.heng.feng@canonical.com>
 <20240320084317.366853-2-kai.heng.feng@canonical.com>
 <ZgFwLXzNG2aTL_BQ@black.fi.intel.com>
From: Guenter Roeck <linux@roeck-us.net>
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In-Reply-To: <ZgFwLXzNG2aTL_BQ@black.fi.intel.com>
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On 3/25/24 05:38, Andy Shevchenko wrote:
> On Wed, Mar 20, 2024 at 04:43:17PM +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 wait until IPMI space handler is installed by
>> acpi_ipmi and also wait until SMI is selected to make the space handler
>> fully functional.
>>
>> Since the dependency is inside BIOS's ASL code and it's not
>> discoverable, so use this fixup is a hack to workaround BIOS issue.
> 
> ...
> 
>> +	if (dmi_match(DMI_SYS_VENDOR, "Dell Inc.")) {
>> +		ipi_device = acpi_dev_get_first_match_dev("IPI0001", NULL, -1);
>> +
>> +		if (ipi_device) {
>> +			if (acpi_wait_for_acpi_ipmi())
>> +				dev_warn(&device->dev, "Waiting for ACPI IPMI timeout");
>> +			acpi_dev_put(ipi_device);
>> +		}
> 
> Can be written as
> 
> 	if (dmi_match(DMI_SYS_VENDOR, "Dell Inc.")) {
> 		ipi_device = acpi_dev_get_first_match_dev("IPI0001", NULL, -1);
> 		if (ipi_device && acpi_wait_for_acpi_ipmi())
> 			dev_warn(&device->dev, "Waiting for ACPI IPMI timeout");
> 		acpi_dev_put(ipi_device);
> 
>> +	}
> 

Ah yes, acpi_dev_put() checks if the parameter is NULL. Good point.
I'll make that change, no need to resend.

Thanks,
Guenter