[PATCH 1/3] ath10k: Add debugging for tx-credits usage.

[Michal Kazior]

On 25 March 2014 16:14, Ben Greear <greearb at candelatech.com> wrote:
> On 03/25/2014 12:27 AM, Michal Kazior wrote:
>>
>> On 24 March 2014 17:50, Ben Greear <greearb at candelatech.com> wrote:
>>>
>>> On 03/24/2014 04:21 AM, Michal Kazior wrote:
>>>>
>>>> On 24 March 2014 12:12, Kalle Valo <kvalo at qca.qualcomm.com> wrote:
>>>
>>>
>>>>>> -     status = ath10k_htc_send(htc, ATH10K_HTC_EP_0, skb);
>>>>>> +     status = ath10k_htc_send(htc, ATH10K_HTC_EP_0, skb, __LINE__);
>>>>>
>>>>>
>>>>> Using line numbers in debug messages is very cumbersome. Some people
>>>>> cherry pick patches, have their own changes and whatnot which will make
>>>>> it more difficult to read the debug logs. Isn't there any better way to
>>>>> do this?
>>>>
>>>>
>>>> I would prefer to explicitly wait for tx credit replenishment in
>>>> ath10k_wmi_cmd_send() after a command is sent instead of all these
>>>> prints. This way you can get a full call trace if it times out.
>>>
>>>
>>> Would that be a performance problem (by effectively allowing only a
>>> single
>>> item to be sent to the firmware at any given time?)
>>
>>
>> The only thing that may suffer here is wmi mgmt tx but I wouldn't
>> consider that performance critical.
>
>
> In that case, why use credits at all?

Excellent question.

Firmware provides 2 HTC tx credits for WMI. I guess this is on
purpose. I imagine WMI mgmt tx can hang (i.e. not replenish tx
credits). In that case the remaining tx credit could be used to try
recovering, e.g. down/stop vdev (I think it should drop all pending tx
and thus free the stuck HTC tx credit).

It might be a good idea to keep this recovery strategy in mind when
implementing the "wait for tx replenishment" wmi tx blocking.


Michał