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

[Kalle Valo]

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?

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