Re: [PATCH 3/4] ath9k: fix the .flush driver op implementation

[Felix Fietkau <nbd@openwrt.org>]

On 2011-03-10 10:25 AM, Vasanthakumar Thiagarajan wrote:
> On Thu, Mar 10, 2011 at 06:05:02AM +0530, Felix Fietkau wrote:
>> ath9k has a timeout of 60ms for the flush, but instead waiting 60 ms for
>> all tx activity to finish, it resets it for every single queue.
> 
> No, it does not do reset for every queue.
You're right, I got confused by the diff and my recollection of an old
version of the flush op ;)

>> +	for (j = 0; j < timeout; j++) {
>> +		int npend = 0;
>> +		for (i = 0; i < ATH9K_NUM_TX_QUEUES; i++) {
>> +			if (!ATH_TXQ_SETUP(sc, i))
>> +				continue;
>>  
>> -		if (drop || ath9k_has_pending_frames(sc, txq)) {
>> -			ath_dbg(common, ATH_DBG_QUEUE, "Drop frames from hw queue:%d\n",
>> -				txq->axq_qnum);
>> -			spin_lock_bh(&txq->axq_lock);
>> -			txq->txq_flush_inprogress = true;
>> -			spin_unlock_bh(&txq->axq_lock);
>> -
>> -			ath9k_ps_wakeup(sc);
>> -			ath9k_hw_stoptxdma(ah, txq->axq_qnum);
>> -			npend = ath9k_hw_numtxpending(ah, txq->axq_qnum);
>> -			ath9k_ps_restore(sc);
>> -			if (npend)
>> -				break;
>> -
>> -			ath_draintxq(sc, txq, false);
>> -			txq->txq_flush_inprogress = false;
>> +			npend += ath9k_has_pending_frames(sc, &sc->tx.txq[i]);
>>  		}
>> -	}
>>  
>> -	if (npend) {
>> -		ath_reset(sc, false);
>> -		txq->txq_flush_inprogress = false;
>> +		if (!npend)
>> +		    goto out;
>> +
>> +		usleep_range(1000, 2000);
> 
> Existing flush gives about 60ms for every q, that is reasonable
> time, but this 60ms for all the queues is too small. This flush
> is also called before sending null func in PS, so reset after
> hw queue stuck is necessary to find the hang early on.
So maybe we should set it to something like 200ms for all? Anything more
than that seems a bit excessive.
I intend to add some more restrictions for the queue lengths soon, then
we can reduce this timeout even further.

> The usage of txq_flush_inprogress needs to be removed in other
> places in xmit.
OK

- Felix