Re: [PATCH wireless-next v2 12/31] wifi: mm81x: add mac.c

[Lachlan Hodges]

Hi Johannes, just having a think about how to do this:

On Thu, Jun 04, 2026 at 01:46:32PM +0200, Johannes Berg wrote:
> 
> > +static void mm81x_mac_ops_flush(struct ieee80211_hw *hw,
> > +				struct ieee80211_vif *vif, u32 queues,
> > +				bool drop)
> > +{
> > +	struct mm81x *mors = hw->priv;
> > +
> > +	/* We don't support IEEE80211_HW_QUEUE_CONTROL so flush all queues */
> > +	if (drop) {
> > +		/*
> > +		 * No need to call mm81x_skbq_stop_tx_queues as mac80211
> > +		 * has already cancelled each queue prior to calling .flush()
> > +		 */
> > +		mm81x_skbq_data_traffic_pause(mors);
> > +
> > +		flush_work(&mors->hif_work);
> > +		flush_work(&mors->tx_stale_work);
> > +
> > +		mm81x_hif_clear_events(mors);
> > +		mm81x_hif_flush_tx_data(mors);
> > +		mm81x_hif_flush_cmds(mors);
> > +
> > +		/* Reenable data, not that there will be any */
> > +		mm81x_skbq_data_traffic_resume(mors);
> > +	}
> > +}
> 
> Doing nothing in the !drop case seems questionable - mac80211 uses this
> sometimes to e.g. make sure a deauth frame really went out before
> shutting down the hardware.

What is the consensus (or I guess your opinion) on using
read_poll_timeout() with a function that isn't really doing any real
I/O but rather just reading software queue state? E.g.:

static void mm81x_mac_wait_queues(struct mm81x *mors)
{
	int remaining;

	if (read_poll_timeout(mm81x_hif_get_tx_outstanding_count, remaining,
			      !remaining, MM81X_FLUSH_DRAIN_POLL_US,
			      MM81X_FLUSH_DRAIN_TIMEOUT_US, false, mors))
		dev_warn(mors->dev,
			 "Unable to empty queues before timeout. Remaining: %d",
			 remaining);
}

where mm81x_hif_get_tx_outstanding_count internally is:

int mm81x_yaps_get_tx_outstanding_count(struct mm81x *mors)
{
	int i;
	int count = 0;
	struct mm81x_yaps *yaps = &mors->hif.u.yaps;

	/* We only care about data + mgmt here */
	count += mm81x_skbq_outstanding(&yaps->mgmt_q);

	for (i = 0; i < ARRAY_SIZE(yaps->data_tx_qs); i++)
		count += mm81x_skbq_outstanding(&yaps->data_tx_qs[i]);

	return count;
}

It is fairly easy to opencode something similar, but this looks nice :)
though I can't see many examples of using it like this so I am
a bit cautious.

lachlan