xref: /freebsd/sys/dev/ath/if_ath_tx_edma.c (revision c243e4902be8df1e643c76b5f18b68bb77cc5268)
1 /*-
2  * Copyright (c) 2012 Adrian Chadd <adrian@FreeBSD.org>
3  * All rights reserved.
4  *
5  * Redistribution and use in source and binary forms, with or without
6  * modification, are permitted provided that the following conditions
7  * are met:
8  * 1. Redistributions of source code must retain the above copyright
9  *    notice, this list of conditions and the following disclaimer,
10  *    without modification.
11  * 2. Redistributions in binary form must reproduce at minimum a disclaimer
12  *    similar to the "NO WARRANTY" disclaimer below ("Disclaimer") and any
13  *    redistribution must be conditioned upon including a substantially
14  *    similar Disclaimer requirement for further binary redistribution.
15  *
16  * NO WARRANTY
17  * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
18  * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
19  * LIMITED TO, THE IMPLIED WARRANTIES OF NONINFRINGEMENT, MERCHANTIBILITY
20  * AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL
21  * THE COPYRIGHT HOLDERS OR CONTRIBUTORS BE LIABLE FOR SPECIAL, EXEMPLARY,
22  * OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
23  * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
24  * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER
25  * IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
26  * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF
27  * THE POSSIBILITY OF SUCH DAMAGES.
28  */
29 
30 #include <sys/cdefs.h>
31 __FBSDID("$FreeBSD$");
32 
33 /*
34  * Driver for the Atheros Wireless LAN controller.
35  *
36  * This software is derived from work of Atsushi Onoe; his contribution
37  * is greatly appreciated.
38  */
39 
40 #include "opt_inet.h"
41 #include "opt_ath.h"
42 /*
43  * This is needed for register operations which are performed
44  * by the driver - eg, calls to ath_hal_gettsf32().
45  *
46  * It's also required for any AH_DEBUG checks in here, eg the
47  * module dependencies.
48  */
49 #include "opt_ah.h"
50 #include "opt_wlan.h"
51 
52 #include <sys/param.h>
53 #include <sys/systm.h>
54 #include <sys/sysctl.h>
55 #include <sys/mbuf.h>
56 #include <sys/malloc.h>
57 #include <sys/lock.h>
58 #include <sys/mutex.h>
59 #include <sys/kernel.h>
60 #include <sys/socket.h>
61 #include <sys/sockio.h>
62 #include <sys/errno.h>
63 #include <sys/callout.h>
64 #include <sys/bus.h>
65 #include <sys/endian.h>
66 #include <sys/kthread.h>
67 #include <sys/taskqueue.h>
68 #include <sys/priv.h>
69 #include <sys/module.h>
70 #include <sys/ktr.h>
71 #include <sys/smp.h>	/* for mp_ncpus */
72 
73 #include <machine/bus.h>
74 
75 #include <net/if.h>
76 #include <net/if_dl.h>
77 #include <net/if_media.h>
78 #include <net/if_types.h>
79 #include <net/if_arp.h>
80 #include <net/ethernet.h>
81 #include <net/if_llc.h>
82 
83 #include <net80211/ieee80211_var.h>
84 #include <net80211/ieee80211_regdomain.h>
85 #ifdef IEEE80211_SUPPORT_SUPERG
86 #include <net80211/ieee80211_superg.h>
87 #endif
88 #ifdef IEEE80211_SUPPORT_TDMA
89 #include <net80211/ieee80211_tdma.h>
90 #endif
91 
92 #include <net/bpf.h>
93 
94 #ifdef INET
95 #include <netinet/in.h>
96 #include <netinet/if_ether.h>
97 #endif
98 
99 #include <dev/ath/if_athvar.h>
100 #include <dev/ath/ath_hal/ah_devid.h>		/* XXX for softled */
101 #include <dev/ath/ath_hal/ah_diagcodes.h>
102 
103 #include <dev/ath/if_ath_debug.h>
104 #include <dev/ath/if_ath_misc.h>
105 #include <dev/ath/if_ath_tsf.h>
106 #include <dev/ath/if_ath_tx.h>
107 #include <dev/ath/if_ath_sysctl.h>
108 #include <dev/ath/if_ath_led.h>
109 #include <dev/ath/if_ath_keycache.h>
110 #include <dev/ath/if_ath_rx.h>
111 #include <dev/ath/if_ath_beacon.h>
112 #include <dev/ath/if_athdfs.h>
113 
114 #ifdef ATH_TX99_DIAG
115 #include <dev/ath/ath_tx99/ath_tx99.h>
116 #endif
117 
118 #include <dev/ath/if_ath_tx_edma.h>
119 
120 /*
121  * some general macros
122  */
123 #define	INCR(_l, _sz)		(_l) ++; (_l) &= ((_sz) - 1)
124 #define	DECR(_l, _sz)		(_l) --; (_l) &= ((_sz) - 1)
125 
126 /*
127  * XXX doesn't belong here, and should be tunable
128  */
129 #define	ATH_TXSTATUS_RING_SIZE	512
130 
131 MALLOC_DECLARE(M_ATHDEV);
132 
133 static void
134 ath_edma_tx_fifo_fill(struct ath_softc *sc, struct ath_txq *txq)
135 {
136 	struct ath_buf *bf;
137 
138 	ATH_TXQ_LOCK_ASSERT(txq);
139 
140 	DPRINTF(sc, ATH_DEBUG_TX_PROC, "%s: called\n", __func__);
141 
142 	TAILQ_FOREACH(bf, &txq->axq_q, bf_list) {
143 		if (txq->axq_fifo_depth >= HAL_TXFIFO_DEPTH)
144 			break;
145 		ath_hal_puttxbuf(sc->sc_ah, txq->axq_qnum, bf->bf_daddr);
146 		txq->axq_fifo_depth++;
147 	}
148 	ath_hal_txstart(sc->sc_ah, txq->axq_qnum);
149 }
150 
151 /*
152  * Re-initialise the DMA FIFO with the current contents of
153  * said TXQ.
154  *
155  * This should only be called as part of the chip reset path, as it
156  * assumes the FIFO is currently empty.
157  *
158  * TODO: verify that a cold/warm reset does clear the TX FIFO, so
159  * writing in a partially-filled FIFO will not cause double-entries
160  * to appear.
161  */
162 static void
163 ath_edma_dma_restart(struct ath_softc *sc, struct ath_txq *txq)
164 {
165 
166 	device_printf(sc->sc_dev, "%s: called: txq=%p, qnum=%d\n",
167 	    __func__,
168 	    txq,
169 	    txq->axq_qnum);
170 
171 	ATH_TXQ_LOCK_ASSERT(txq);
172 	ath_edma_tx_fifo_fill(sc, txq);
173 
174 }
175 
176 /*
177  * Hand off this frame to a hardware queue.
178  *
179  * Things are a bit hairy in the EDMA world.  The TX FIFO is only
180  * 8 entries deep, so we need to keep track of exactly what we've
181  * pushed into the FIFO and what's just sitting in the TX queue,
182  * waiting to go out.
183  *
184  * So this is split into two halves - frames get appended to the
185  * TXQ; then a scheduler is called to push some frames into the
186  * actual TX FIFO.
187  */
188 static void
189 ath_edma_xmit_handoff_hw(struct ath_softc *sc, struct ath_txq *txq,
190     struct ath_buf *bf)
191 {
192 	struct ath_hal *ah = sc->sc_ah;
193 
194 	ATH_TXQ_LOCK_ASSERT(txq);
195 
196 	KASSERT((bf->bf_flags & ATH_BUF_BUSY) == 0,
197 	    ("%s: busy status 0x%x", __func__, bf->bf_flags));
198 
199 	/*
200 	 * XXX TODO: write a hard-coded check to ensure that
201 	 * the queue id in the TX descriptor matches txq->axq_qnum.
202 	 */
203 
204 	/* Update aggr stats */
205 	if (bf->bf_state.bfs_aggr)
206 		txq->axq_aggr_depth++;
207 
208 	/* Push and update frame stats */
209 	ATH_TXQ_INSERT_TAIL(txq, bf, bf_list);
210 
211 #ifdef	ATH_DEBUG
212 	if (sc->sc_debug & ATH_DEBUG_XMIT_DESC)
213 		ath_printtxbuf(sc, bf, txq->axq_qnum, 0, 0);
214 #endif	/* ATH_DEBUG */
215 
216 	/* Only schedule to the FIFO if there's space */
217 	if (txq->axq_fifo_depth < HAL_TXFIFO_DEPTH) {
218 		ath_hal_puttxbuf(ah, txq->axq_qnum, bf->bf_daddr);
219 		txq->axq_fifo_depth++;
220 		ath_hal_txstart(ah, txq->axq_qnum);
221 	}
222 }
223 
224 /*
225  * Hand off this frame to a multicast software queue.
226  *
227  * Unlike legacy DMA, this doesn't chain together frames via the
228  * link pointer.  Instead, they're just added to the queue.
229  * When it comes time to populate the CABQ, these frames should
230  * be individually pushed into the FIFO as appropriate.
231  *
232  * Yes, this does mean that I'll eventually have to flesh out some
233  * replacement code to handle populating the CABQ, rather than
234  * what's done in ath_beacon_generate().  It'll have to push each
235  * frame from the HW CABQ to the FIFO rather than just appending
236  * it to the existing TXQ and kicking off DMA.
237  */
238 static void
239 ath_edma_xmit_handoff_mcast(struct ath_softc *sc, struct ath_txq *txq,
240     struct ath_buf *bf)
241 {
242 
243 	ATH_TXQ_LOCK_ASSERT(txq);
244 	KASSERT((bf->bf_flags & ATH_BUF_BUSY) == 0,
245 	    ("%s: busy status 0x%x", __func__, bf->bf_flags));
246 
247 	/*
248 	 * XXX this is mostly duplicated in ath_tx_handoff_mcast().
249 	 */
250 	if (ATH_TXQ_FIRST(txq) != NULL) {
251 		struct ath_buf *bf_last = ATH_TXQ_LAST(txq, axq_q_s);
252 		struct ieee80211_frame *wh;
253 
254 		/* mark previous frame */
255 		wh = mtod(bf_last->bf_m, struct ieee80211_frame *);
256 		wh->i_fc[1] |= IEEE80211_FC1_MORE_DATA;
257 
258 		/* sync descriptor to memory */
259 		bus_dmamap_sync(sc->sc_dmat, bf_last->bf_dmamap,
260 		   BUS_DMASYNC_PREWRITE);
261 	}
262 
263 	ATH_TXQ_INSERT_TAIL(txq, bf, bf_list);
264 }
265 
266 /*
267  * Handoff this frame to the hardware.
268  *
269  * For the multicast queue, this will treat it as a software queue
270  * and append it to the list, after updating the MORE_DATA flag
271  * in the previous frame.  The cabq processing code will ensure
272  * that the queue contents gets transferred over.
273  *
274  * For the hardware queues, this will queue a frame to the queue
275  * like before, then populate the FIFO from that.  Since the
276  * EDMA hardware has 8 FIFO slots per TXQ, this ensures that
277  * frames such as management frames don't get prematurely dropped.
278  *
279  * This does imply that a similar flush-hwq-to-fifoq method will
280  * need to be called from the processq function, before the
281  * per-node software scheduler is called.
282  */
283 static void
284 ath_edma_xmit_handoff(struct ath_softc *sc, struct ath_txq *txq,
285     struct ath_buf *bf)
286 {
287 
288 	ATH_TXQ_LOCK_ASSERT(txq);
289 
290 	DPRINTF(sc, ATH_DEBUG_XMIT_DESC,
291 	    "%s: called; bf=%p, txq=%p, qnum=%d\n",
292 	    __func__,
293 	    bf,
294 	    txq,
295 	    txq->axq_qnum);
296 
297 	if (txq->axq_qnum == ATH_TXQ_SWQ)
298 		ath_edma_xmit_handoff_mcast(sc, txq, bf);
299 	else
300 		ath_edma_xmit_handoff_hw(sc, txq, bf);
301 
302 #if 0
303 	/*
304 	 * XXX For now this is a placeholder; free the buffer
305 	 * and inform the stack that the TX failed.
306 	 */
307 	ath_tx_default_comp(sc, bf, 1);
308 #endif
309 }
310 
311 static int
312 ath_edma_setup_txfifo(struct ath_softc *sc, int qnum)
313 {
314 	struct ath_tx_edma_fifo *te = &sc->sc_txedma[qnum];
315 
316 	te->m_fifo = malloc(sizeof(struct ath_buf *) * HAL_TXFIFO_DEPTH,
317 	    M_ATHDEV,
318 	    M_NOWAIT | M_ZERO);
319 	if (te->m_fifo == NULL) {
320 		device_printf(sc->sc_dev, "%s: malloc failed\n",
321 		    __func__);
322 		return (-ENOMEM);
323 	}
324 
325 	/*
326 	 * Set initial "empty" state.
327 	 */
328 	te->m_fifo_head = te->m_fifo_tail = te->m_fifo_depth = 0;
329 
330 	return (0);
331 }
332 
333 static int
334 ath_edma_free_txfifo(struct ath_softc *sc, int qnum)
335 {
336 	struct ath_tx_edma_fifo *te = &sc->sc_txedma[qnum];
337 
338 	/* XXX TODO: actually deref the ath_buf entries? */
339 	free(te->m_fifo, M_ATHDEV);
340 	return (0);
341 }
342 
343 static int
344 ath_edma_dma_txsetup(struct ath_softc *sc)
345 {
346 	int error;
347 	int i;
348 
349 	error = ath_descdma_alloc_desc(sc, &sc->sc_txsdma,
350 	    NULL, "txcomp", sc->sc_tx_statuslen, ATH_TXSTATUS_RING_SIZE);
351 	if (error != 0)
352 		return (error);
353 
354 	ath_hal_setuptxstatusring(sc->sc_ah,
355 	    (void *) sc->sc_txsdma.dd_desc,
356 	    sc->sc_txsdma.dd_desc_paddr,
357 	    ATH_TXSTATUS_RING_SIZE);
358 
359 	for (i = 0; i < HAL_NUM_TX_QUEUES; i++) {
360 		ath_edma_setup_txfifo(sc, i);
361 	}
362 
363 
364 	return (0);
365 }
366 
367 static int
368 ath_edma_dma_txteardown(struct ath_softc *sc)
369 {
370 	int i;
371 
372 	for (i = 0; i < HAL_NUM_TX_QUEUES; i++) {
373 		ath_edma_free_txfifo(sc, i);
374 	}
375 
376 	ath_descdma_cleanup(sc, &sc->sc_txsdma, NULL);
377 	return (0);
378 }
379 
380 /*
381  * Drain all TXQs, potentially after completing the existing completed
382  * frames.
383  */
384 static void
385 ath_edma_tx_drain(struct ath_softc *sc, ATH_RESET_TYPE reset_type)
386 {
387 	struct ifnet *ifp = sc->sc_ifp;
388 	int i;
389 
390 	device_printf(sc->sc_dev, "%s: called\n", __func__);
391 
392 	(void) ath_stoptxdma(sc);
393 
394 	/*
395 	 * If reset type is noloss, the TX FIFO needs to be serviced
396 	 * and those frames need to be handled.
397 	 *
398 	 * Otherwise, just toss everything in each TX queue.
399 	 */
400 
401 	/* XXX dump out the TX completion FIFO contents */
402 
403 	/* XXX dump out the frames */
404 
405 	/* XXX for now, just drain */
406 	for (i = 0; i < HAL_NUM_TX_QUEUES; i++) {
407 		if (ATH_TXQ_SETUP(sc, i))
408 			ath_tx_draintxq(sc, &sc->sc_txq[i]);
409 	}
410 
411 	IF_LOCK(&ifp->if_snd);
412 	ifp->if_drv_flags &= ~IFF_DRV_OACTIVE;
413 	IF_UNLOCK(&ifp->if_snd);
414 	sc->sc_wd_timer = 0;
415 }
416 
417 /*
418  * Process the TX status queue.
419  */
420 static void
421 ath_edma_tx_proc(void *arg, int npending)
422 {
423 	struct ath_softc *sc = (struct ath_softc *) arg;
424 	struct ath_hal *ah = sc->sc_ah;
425 	HAL_STATUS status;
426 	struct ath_tx_status ts;
427 	struct ath_txq *txq;
428 	struct ath_buf *bf;
429 	struct ieee80211_node *ni;
430 	int nacked = 0;
431 
432 	DPRINTF(sc, ATH_DEBUG_TX_PROC, "%s: called, npending=%d\n",
433 	    __func__, npending);
434 
435 	for (;;) {
436 		bzero(&ts, sizeof(ts));
437 
438 		ATH_TXSTATUS_LOCK(sc);
439 		status = ath_hal_txprocdesc(ah, NULL, (void *) &ts);
440 		ATH_TXSTATUS_UNLOCK(sc);
441 
442 		if (status == HAL_EINPROGRESS)
443 			break;
444 
445 		/*
446 		 * If there is an error with this descriptor, continue
447 		 * processing.
448 		 *
449 		 * XXX TBD: log some statistics?
450 		 */
451 		if (status == HAL_EIO) {
452 			device_printf(sc->sc_dev, "%s: invalid TX status?\n",
453 			    __func__);
454 			continue;
455 		}
456 
457 		/*
458 		 * At this point we have a valid status descriptor.
459 		 * The QID and descriptor ID (which currently isn't set)
460 		 * is part of the status.
461 		 *
462 		 * We then assume that the descriptor in question is the
463 		 * -head- of the given QID.  Eventually we should verify
464 		 * this by using the descriptor ID.
465 		 */
466 
467 		/*
468 		 * The beacon queue is not currently a "real" queue.
469 		 * Frames aren't pushed onto it and the lock isn't setup.
470 		 * So skip it for now; the beacon handling code will
471 		 * free and alloc more beacon buffers as appropriate.
472 		 */
473 		if (ts.ts_queue_id == sc->sc_bhalq)
474 			continue;
475 
476 		txq = &sc->sc_txq[ts.ts_queue_id];
477 
478 		ATH_TXQ_LOCK(txq);
479 		bf = TAILQ_FIRST(&txq->axq_q);
480 
481 		DPRINTF(sc, ATH_DEBUG_TX_PROC, "%s: qcuid=%d, bf=%p\n",
482 		    __func__,
483 		    ts.ts_queue_id, bf);
484 
485 #if 0
486 		/* XXX assert the buffer/descriptor matches the status descid */
487 		if (ts.ts_desc_id != bf->bf_descid) {
488 			device_printf(sc->sc_dev,
489 			    "%s: mismatched descid (qid=%d, tsdescid=%d, "
490 			    "bfdescid=%d\n",
491 			    __func__,
492 			    ts.ts_queue_id,
493 			    ts.ts_desc_id,
494 			    bf->bf_descid);
495 		}
496 #endif
497 
498 		/* This removes the buffer and decrements the queue depth */
499 		ATH_TXQ_REMOVE(txq, bf, bf_list);
500 		if (bf->bf_state.bfs_aggr)
501 			txq->axq_aggr_depth--;
502 		txq->axq_fifo_depth --;
503 		/* XXX assert FIFO depth >= 0 */
504 		ATH_TXQ_UNLOCK(txq);
505 
506 		/*
507 		 * First we need to make sure ts_rate is valid.
508 		 *
509 		 * Pre-EDMA chips pass the whole TX descriptor to
510 		 * the proctxdesc function which will then fill out
511 		 * ts_rate based on the ts_finaltsi (final TX index)
512 		 * in the TX descriptor.  However the TX completion
513 		 * FIFO doesn't have this information.  So here we
514 		 * do a separate HAL call to populate that information.
515 		 */
516 
517 		/* XXX TODO */
518 		/* XXX faked for now. Ew. */
519 		if (ts.ts_finaltsi < 4) {
520 			ts.ts_rate =
521 			    bf->bf_state.bfs_rc[ts.ts_finaltsi].ratecode;
522 		} else {
523 			device_printf(sc->sc_dev, "%s: finaltsi=%d\n",
524 			    __func__,
525 			    ts.ts_finaltsi);
526 			ts.ts_rate = bf->bf_state.bfs_rc[0].ratecode;
527 		}
528 
529 		/*
530 		 * XXX This is terrible.
531 		 *
532 		 * Right now, some code uses the TX status that is
533 		 * passed in here, but the completion handlers in the
534 		 * software TX path also use bf_status.ds_txstat.
535 		 * Ew.  That should all go away.
536 		 *
537 		 * XXX It's also possible the rate control completion
538 		 * routine is called twice.
539 		 */
540 		memcpy(&bf->bf_status, &ts, sizeof(ts));
541 
542 		ni = bf->bf_node;
543 
544 		/* Update RSSI */
545 		/* XXX duplicate from ath_tx_processq */
546 		if (ni != NULL && ts.ts_status == 0 &&
547 		    ((bf->bf_state.bfs_txflags & HAL_TXDESC_NOACK) == 0)) {
548 			nacked++;
549 			sc->sc_stats.ast_tx_rssi = ts.ts_rssi;
550 			ATH_RSSI_LPF(sc->sc_halstats.ns_avgtxrssi,
551 			    ts.ts_rssi);
552 		}
553 
554 		/* Handle frame completion and rate control update */
555 		ath_tx_process_buf_completion(sc, txq, &ts, bf);
556 
557 		/* bf is invalid at this point */
558 
559 		/*
560 		 * Now that there's space in the FIFO, let's push some
561 		 * more frames into it.
562 		 *
563 		 * Unfortunately for now, the txq has FIFO and non-FIFO
564 		 * frames in the same linked list, so there's no way
565 		 * to quickly/easily populate frames without walking
566 		 * the queue and skipping 'axq_fifo_depth' frames.
567 		 *
568 		 * So for now, let's only repopulate the FIFO once it
569 		 * is empty.  It's sucky for performance but it's enough
570 		 * to begin validating that things are somewhat
571 		 * working.
572 		 */
573 		ATH_TXQ_LOCK(txq);
574 		if (txq->axq_fifo_depth == 0) {
575 			ath_edma_tx_fifo_fill(sc, txq);
576 		}
577 		ATH_TXQ_UNLOCK(txq);
578 	}
579 
580 	sc->sc_wd_timer = 0;
581 
582 	/* Kick software scheduler */
583 	/*
584 	 * XXX It's inefficient to do this if the FIFO queue is full,
585 	 * but there's no easy way right now to only populate
586 	 * the txq task for _one_ TXQ.  This should be fixed.
587 	 */
588 	taskqueue_enqueue(sc->sc_tq, &sc->sc_txqtask);
589 }
590 
591 static void
592 ath_edma_attach_comp_func(struct ath_softc *sc)
593 {
594 
595 	TASK_INIT(&sc->sc_txtask, 0, ath_edma_tx_proc, sc);
596 }
597 
598 void
599 ath_xmit_setup_edma(struct ath_softc *sc)
600 {
601 
602 	/* Fetch EDMA field and buffer sizes */
603 	(void) ath_hal_gettxdesclen(sc->sc_ah, &sc->sc_tx_desclen);
604 	(void) ath_hal_gettxstatuslen(sc->sc_ah, &sc->sc_tx_statuslen);
605 	(void) ath_hal_getntxmaps(sc->sc_ah, &sc->sc_tx_nmaps);
606 
607 	device_printf(sc->sc_dev, "TX descriptor length: %d\n",
608 	    sc->sc_tx_desclen);
609 	device_printf(sc->sc_dev, "TX status length: %d\n",
610 	    sc->sc_tx_statuslen);
611 	device_printf(sc->sc_dev, "TX buffers per descriptor: %d\n",
612 	    sc->sc_tx_nmaps);
613 
614 	sc->sc_tx.xmit_setup = ath_edma_dma_txsetup;
615 	sc->sc_tx.xmit_teardown = ath_edma_dma_txteardown;
616 	sc->sc_tx.xmit_attach_comp_func = ath_edma_attach_comp_func;
617 
618 	sc->sc_tx.xmit_dma_restart = ath_edma_dma_restart;
619 	sc->sc_tx.xmit_handoff = ath_edma_xmit_handoff;
620 	sc->sc_tx.xmit_drain = ath_edma_tx_drain;
621 }
622