ath10k: Fix reported HT MCS rates with NSS > 1

[Kalle Valo]

Peter Oh <peter.oh at bowerswilkins.com> writes:

> On 11/06/2017 01:02 AM, Sven Eckelmann wrote:
>> On Montag, 6. November 2017 09:28:42 CET Sebastian Gottschall wrote:
>>> Am 06.11.2017 um 09:23 schrieb Sven Eckelmann:
>>>> On Sonntag, 5. November 2017 10:22:22 CET Sebastian Gottschall wrote:
>>>>> the assumption made in this patch is obviously wrong (at least for more
>>>>> recent firmwares and 9984)
>>>>> my log is flooded with messages like
>>>>> [208802.803537] ath10k_pci 0001:03:00.0: Invalid VHT mcs 15 peer stats
>>>>> [208805.108515] ath10k_pci 0001:03:00.0: Invalid VHT mcs 15 peer stats
>>>>> [208821.747621] ath10k_pci 0001:03:00.0: Invalid VHT mcs 15 peer stats
>>>>> [208822.516599] ath10k_pci 0001:03:00.0: Invalid VHT mcs 15 peer stats
>>>>> [208841.257780] ath10k_pci 0001:03:00.0: Invalid VHT mcs 15 peer stats
>> [...]
>>>> This patch only splits WMI_RATE_PREAMBLE_HT & WMI_RATE_PREAMBLE_VHT. And for
>>>> WMI_RATE_PREAMBLE_HT (*not VHT*), it uses a slightly different approach. But
>>>> the WMI_RATE_PREAMBLE_VHT part (which you see in your logs) is basically
>>>> untouched.
>>> then a question follows up. is this check really neccessary?
>> Until we find out what the heck VHT MCS 15 should mean in this context - maybe.
>> But to the message - no, the message is most likely not necessary for each
>> received "invalid" peer tx stat.
>
> This validation check expects peer tx stat packets from FW contain
> reasonable values and gives warning if values are different from
> expectation. The problem comes from the assumption that "it always
> contains reasonable stat value" which is wrong at least based on my
> results. For instance, the reason MCS == 15 is because all 4 bits of
> mcs potion set to 1, not because FW really sets it to 15
> intentionally. when the mcs potion bits are set to all 1s, the other
> bits such as nss are also set to all 1s.
> Hence it looks FW passed totally invalid stat info to me.
>
> I don't have preference on whether it's better to split VHT and HT
> check or not, but it is more appropriate to change that warning level
> to debug level.

I think we should add a special case to not print the warning if mcs ==
15 until we figure out what it means.

-- 
Kalle Valo