Re: [PATCH] wifi: iwlwifi: acpi/dsm: cache error retcode for iwl_acpi_get_dsm

[David Wang]

At 2024-08-27 14:26:42, "Kalle Valo" <kvalo@xxxxxxxxxx> wrote:
>David Wang <00107082@xxxxxxx> writes:
>
>> On some HW, acpi _DSM query would failed for iwlwifi device
>> and everytime when network is reactiaved (boot,
>> suspend/resume, manually restart network, etc.),
>> bunch of kernel warning shows up together:
>>   ACPI: \: failed to evaluate _DSM bf0212f2-788f-c64d-a5b3-1f738e285ade (0x1001)
>>   ACPI: \: failed to evaluate _DSM bf0212f2-788f-c64d-a5b3-1f738e285ade (0x1001)
>>   ACPI: \: failed to evaluate _DSM bf0212f2-788f-c64d-a5b3-1f738e285ade (0x1001)
>>   ACPI: \: failed to evaluate _DSM bf0212f2-788f-c64d-a5b3-1f738e285ade (0x1001)
>>   ACPI: \: failed to evaluate _DSM bf0212f2-788f-c64d-a5b3-1f738e285ade (0x1001)
>>   ACPI: \: failed to evaluate _DSM bf0212f2-788f-c64d-a5b3-1f738e285ade (0x1001)
>>   ACPI: \: failed to evaluate _DSM bf0212f2-788f-c64d-a5b3-1f738e285ade (0x1001)
>>   ACPI: \: failed to evaluate _DSM bf0212f2-788f-c64d-a5b3-1f738e285ade (0x1001)
>> since iwlwifi would make 8 acpi/dsm queries for lari config.
>> But for iwlwifi, it is safe to cache the _DSM errors,
>> since it is not possible to correct it without upgrading BIOS.
>> With this patch, those kernel warnings would only show up once when
>> booting the system and unnecessary acpi/dsm queries are avoid.
>>
>> Signed-off-by: David Wang <00107082@xxxxxxx>
>> ---
>>  drivers/net/wireless/intel/iwlwifi/fw/acpi.c | 7 +++++++
>>  1 file changed, 7 insertions(+)
>>
>> diff --git a/drivers/net/wireless/intel/iwlwifi/fw/acpi.c b/drivers/net/wireless/intel/iwlwifi/fw/acpi.c
>> index 79774c8c7ff4..3f98f522daac 100644
>> --- a/drivers/net/wireless/intel/iwlwifi/fw/acpi.c
>> +++ b/drivers/net/wireless/intel/iwlwifi/fw/acpi.c
>> @@ -30,6 +30,8 @@ static const size_t acpi_dsm_size[DSM_FUNC_NUM_FUNCS] = {
>>  	[DSM_FUNC_ENABLE_11BE] =		sizeof(u32),
>>  };
>>  
>> +static int acpi_dsm_func_retcode[DSM_FUNC_NUM_FUNCS] = {0};
>> +
>>  static int iwl_acpi_get_handle(struct device *dev, acpi_string method,
>>  			       acpi_handle *ret_handle)
>>  {
>> @@ -169,6 +171,10 @@ int iwl_acpi_get_dsm(struct iwl_fw_runtime *fwrt,
>>  	if (WARN_ON(func >= ARRAY_SIZE(acpi_dsm_size)))
>>  		return -EINVAL;
>>  
>> +	/* If HW return an error once, do not bother try again. */
>> +	if (acpi_dsm_func_retcode[func])
>> +		return acpi_dsm_func_retcode[func];
>
>Static variables are usually avoided because they are problematic if
>there are multiple iwlwifi devices on the same host. Should the error
>message be just removed entirely?

Thanks for the review~
Yep,  you're quite right! I did not consider multiple iwlwifi devices.

The repeated error messages really bother  me,  but they are from acpi driver, I don't think it can be removed  entirely....

Would moving the cache into device structure acceptable?


Thanks
David 

>
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>
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