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SubjectRe: [PATCH] iwlwifi: pcie: reduce "unsupported splx" to a warning
Hi,
On Mon, 2016-10-10 at 02:19 -0500, Chris Rorvick wrote:
> Commit bcb079a14d75 ("iwlwifi: pcie: retrieve and parse ACPI power
> limitations") looks for a specific structure in the ACPI tables for
> setting the default power limit. The data returned for at least some
> dual band chipsets is not recognized, though. For example, the AC 8260
> reports the following:

This is not coming from the NIC itself, but from the platform's ACPI
tables.  Can you tell us which platform you are using?


> Name (SPLX, Package (0x04)
> {
> Zero,
> Package (0x03)
> {
> 0,
> 1200,
> 1000
> },
> Package (0x03)
> {
> 0,
> 1200,
> 1000
> },
> Package (0x03)
> {
> 0,
> 1200,
> 1000
> }
> })

This is not the structure that we are expecting. We expect this:

Name (SPLX, Package (0x02)
{
Zero,
Package (0x03)
{
0x07,
<value>,
<value>
}
})

...as you correctly pointed out. The data in the structure you have is
not for WiFi (actually I don't think 0 is a valid value, but I'll
double-check).


> The current logic expects exactly two elements in the outer package,
> causing the above to be ignored and the power limit unset.
>
> Despite the interface being fully functional after initialization, the
> above condition is reported as an error. Knock the message down to a
> warning and provide better context for understanding its consequence.

Reducing this to a warning is an easy way to reduce the verbosity of
the problem, but I think the correct thing to do would be to accept
multiple entries and ignore the ones that don't have the WIFI marker.
 And only type-check the WIFI ones.

There are other things that look a bit inconsistent in this code...
I'll try to find the official ACPI table definitions for this entries
to make sure it's correct.


> Signed-off-by: Chris Rorvick <chris@rorvick.com>
> ---
> drivers/net/wireless/intel/iwlwifi/pcie/drv.c | 2 +-
> 1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/drivers/net/wireless/intel/iwlwifi/pcie/drv.c b/drivers/net/wireless/intel/iwlwifi/pcie/drv.c
> index 78cf9a7..19b531f 100644
> --- a/drivers/net/wireless/intel/iwlwifi/pcie/drv.c
> +++ b/drivers/net/wireless/intel/iwlwifi/pcie/drv.c
> @@ -540,7 +540,7 @@ static u64 splx_get_pwr_limit(struct iwl_trans *trans, union acpi_object *splx)
> splx->package.count != 2 ||
> splx->package.elements[0].type != ACPI_TYPE_INTEGER ||
> splx->package.elements[0].integer.value != 0) {
> - IWL_ERR(trans, "Unsupported splx structure\n");
> + IWL_WARN(trans, "Unsupported splx structure, not limiting WiFi power\n");
> return 0;
> }

If this is really bothering you, I guess I could apply this patch for
now. But as I said, this is not solving the actual problem.

--
Cheers,
Luca.

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