summaryrefslogtreecommitdiff
path: root/drivers/net/wireless/ath/ath9k/recv.c
blob: 1ca42e5148c81ba72935899a931125b1a60b2d1a (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
479
480
481
482
483
484
485
486
487
488
489
490
491
492
493
494
495
496
497
498
499
500
501
502
503
504
505
506
507
508
509
510
511
512
513
514
515
516
517
518
519
520
521
522
523
524
525
526
527
528
529
530
531
532
533
534
535
536
537
538
539
540
541
542
543
544
545
546
547
548
549
550
551
552
553
554
555
556
557
558
559
560
561
562
563
564
565
566
567
568
569
570
571
572
573
574
575
576
577
578
579
580
581
582
583
584
585
586
587
588
589
590
591
592
593
594
595
596
597
598
599
600
601
602
603
604
605
606
607
608
609
610
611
612
613
614
615
616
617
618
619
620
621
622
623
624
625
626
627
628
629
630
631
632
633
634
635
636
637
638
639
640
641
642
643
644
645
646
647
648
649
650
651
652
/*
 * Copyright (c) 2008-2009 Atheros Communications Inc.
 *
 * Permission to use, copy, modify, and/or distribute this software for any
 * purpose with or without fee is hereby granted, provided that the above
 * copyright notice and this permission notice appear in all copies.
 *
 * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
 * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
 * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
 * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
 * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
 * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
 * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
 */

#include "ath9k.h"

static struct ieee80211_hw * ath_get_virt_hw(struct ath_softc *sc,
					     struct ieee80211_hdr *hdr)
{
	struct ieee80211_hw *hw = sc->pri_wiphy->hw;
	int i;

	spin_lock_bh(&sc->wiphy_lock);
	for (i = 0; i < sc->num_sec_wiphy; i++) {
		struct ath_wiphy *aphy = sc->sec_wiphy[i];
		if (aphy == NULL)
			continue;
		if (compare_ether_addr(hdr->addr1, aphy->hw->wiphy->perm_addr)
		    == 0) {
			hw = aphy->hw;
			break;
		}
	}
	spin_unlock_bh(&sc->wiphy_lock);
	return hw;
}

/*
 * Setup and link descriptors.
 *
 * 11N: we can no longer afford to self link the last descriptor.
 * MAC acknowledges BA status as long as it copies frames to host
 * buffer (or rx fifo). This can incorrectly acknowledge packets
 * to a sender if last desc is self-linked.
 */
static void ath_rx_buf_link(struct ath_softc *sc, struct ath_buf *bf)
{
	struct ath_hw *ah = sc->sc_ah;
	struct ath_common *common = ath9k_hw_common(ah);
	struct ath_desc *ds;
	struct sk_buff *skb;

	ATH_RXBUF_RESET(bf);

	ds = bf->bf_desc;
	ds->ds_link = 0; /* link to null */
	ds->ds_data = bf->bf_buf_addr;

	/* virtual addr of the beginning of the buffer. */
	skb = bf->bf_mpdu;
	BUG_ON(skb == NULL);
	ds->ds_vdata = skb->data;

	/*
	 * setup rx descriptors. The rx_bufsize here tells the hardware
	 * how much data it can DMA to us and that we are prepared
	 * to process
	 */
	ath9k_hw_setuprxdesc(ah, ds,
			     common->rx_bufsize,
			     0);

	if (sc->rx.rxlink == NULL)
		ath9k_hw_putrxbuf(ah, bf->bf_daddr);
	else
		*sc->rx.rxlink = bf->bf_daddr;

	sc->rx.rxlink = &ds->ds_link;
	ath9k_hw_rxena(ah);
}

static void ath_setdefantenna(struct ath_softc *sc, u32 antenna)
{
	/* XXX block beacon interrupts */
	ath9k_hw_setantenna(sc->sc_ah, antenna);
	sc->rx.defant = antenna;
	sc->rx.rxotherant = 0;
}

static void ath_opmode_init(struct ath_softc *sc)
{
	struct ath_hw *ah = sc->sc_ah;
	struct ath_common *common = ath9k_hw_common(ah);

	u32 rfilt, mfilt[2];

	/* configure rx filter */
	rfilt = ath_calcrxfilter(sc);
	ath9k_hw_setrxfilter(ah, rfilt);

	/* configure bssid mask */
	if (ah->caps.hw_caps & ATH9K_HW_CAP_BSSIDMASK)
		ath_hw_setbssidmask(common);

	/* configure operational mode */
	ath9k_hw_setopmode(ah);

	/* Handle any link-level address change. */
	ath9k_hw_setmac(ah, common->macaddr);

	/* calculate and install multicast filter */
	mfilt[0] = mfilt[1] = ~0;
	ath9k_hw_setmcastfilter(ah, mfilt[0], mfilt[1]);
}

int ath_rx_init(struct ath_softc *sc, int nbufs)
{
	struct ath_common *common = ath9k_hw_common(sc->sc_ah);
	struct sk_buff *skb;
	struct ath_buf *bf;
	int error = 0;

	spin_lock_init(&sc->rx.rxflushlock);
	sc->sc_flags &= ~SC_OP_RXFLUSH;
	spin_lock_init(&sc->rx.rxbuflock);

	common->rx_bufsize = roundup(IEEE80211_MAX_MPDU_LEN,
				     min(common->cachelsz, (u16)64));

	ath_print(common, ATH_DBG_CONFIG, "cachelsz %u rxbufsize %u\n",
		  common->cachelsz, common->rx_bufsize);

	/* Initialize rx descriptors */

	error = ath_descdma_setup(sc, &sc->rx.rxdma, &sc->rx.rxbuf,
				  "rx", nbufs, 1);
	if (error != 0) {
		ath_print(common, ATH_DBG_FATAL,
			  "failed to allocate rx descriptors: %d\n", error);
		goto err;
	}

	list_for_each_entry(bf, &sc->rx.rxbuf, list) {
		skb = ath_rxbuf_alloc(common, common->rx_bufsize, GFP_KERNEL);
		if (skb == NULL) {
			error = -ENOMEM;
			goto err;
		}

		bf->bf_mpdu = skb;
		bf->bf_buf_addr = dma_map_single(sc->dev, skb->data,
						 common->rx_bufsize,
						 DMA_FROM_DEVICE);
		if (unlikely(dma_mapping_error(sc->dev,
					       bf->bf_buf_addr))) {
			dev_kfree_skb_any(skb);
			bf->bf_mpdu = NULL;
			ath_print(common, ATH_DBG_FATAL,
				  "dma_mapping_error() on RX init\n");
			error = -ENOMEM;
			goto err;
		}
		bf->bf_dmacontext = bf->bf_buf_addr;
	}
	sc->rx.rxlink = NULL;

err:
	if (error)
		ath_rx_cleanup(sc);

	return error;
}

void ath_rx_cleanup(struct ath_softc *sc)
{
	struct ath_hw *ah = sc->sc_ah;
	struct ath_common *common = ath9k_hw_common(ah);
	struct sk_buff *skb;
	struct ath_buf *bf;

	list_for_each_entry(bf, &sc->rx.rxbuf, list) {
		skb = bf->bf_mpdu;
		if (skb) {
			dma_unmap_single(sc->dev, bf->bf_buf_addr,
					 common->rx_bufsize, DMA_FROM_DEVICE);
			dev_kfree_skb(skb);
		}
	}

	if (sc->rx.rxdma.dd_desc_len != 0)
		ath_descdma_cleanup(sc, &sc->rx.rxdma, &sc->rx.rxbuf);
}

/*
 * Calculate the receive filter according to the
 * operating mode and state:
 *
 * o always accept unicast, broadcast, and multicast traffic
 * o maintain current state of phy error reception (the hal
 *   may enable phy error frames for noise immunity work)
 * o probe request frames are accepted only when operating in
 *   hostap, adhoc, or monitor modes
 * o enable promiscuous mode according to the interface state
 * o accept beacons:
 *   - when operating in adhoc mode so the 802.11 layer creates
 *     node table entries for peers,
 *   - when operating in station mode for collecting rssi data when
 *     the station is otherwise quiet, or
 *   - when operating as a repeater so we see repeater-sta beacons
 *   - when scanning
 */

u32 ath_calcrxfilter(struct ath_softc *sc)
{
#define	RX_FILTER_PRESERVE (ATH9K_RX_FILTER_PHYERR | ATH9K_RX_FILTER_PHYRADAR)

	u32 rfilt;

	rfilt = (ath9k_hw_getrxfilter(sc->sc_ah) & RX_FILTER_PRESERVE)
		| ATH9K_RX_FILTER_UCAST | ATH9K_RX_FILTER_BCAST
		| ATH9K_RX_FILTER_MCAST;

	/* If not a STA, enable processing of Probe Requests */
	if (sc->sc_ah->opmode != NL80211_IFTYPE_STATION)
		rfilt |= ATH9K_RX_FILTER_PROBEREQ;

	/*
	 * Set promiscuous mode when FIF_PROMISC_IN_BSS is enabled for station
	 * mode interface or when in monitor mode. AP mode does not need this
	 * since it receives all in-BSS frames anyway.
	 */
	if (((sc->sc_ah->opmode != NL80211_IFTYPE_AP) &&
	     (sc->rx.rxfilter & FIF_PROMISC_IN_BSS)) ||
	    (sc->sc_ah->opmode == NL80211_IFTYPE_MONITOR))
		rfilt |= ATH9K_RX_FILTER_PROM;

	if (sc->rx.rxfilter & FIF_CONTROL)
		rfilt |= ATH9K_RX_FILTER_CONTROL;

	if ((sc->sc_ah->opmode == NL80211_IFTYPE_STATION) &&
	    !(sc->rx.rxfilter & FIF_BCN_PRBRESP_PROMISC))
		rfilt |= ATH9K_RX_FILTER_MYBEACON;
	else
		rfilt |= ATH9K_RX_FILTER_BEACON;

	if ((AR_SREV_9280_10_OR_LATER(sc->sc_ah) ||
	    AR_SREV_9285_10_OR_LATER(sc->sc_ah)) &&
	    (sc->sc_ah->opmode == NL80211_IFTYPE_AP) &&
	    (sc->rx.rxfilter & FIF_PSPOLL))
		rfilt |= ATH9K_RX_FILTER_PSPOLL;

	if (conf_is_ht(&sc->hw->conf))
		rfilt |= ATH9K_RX_FILTER_COMP_BAR;

	if (sc->sec_wiphy || (sc->rx.rxfilter & FIF_OTHER_BSS)) {
		/* TODO: only needed if more than one BSSID is in use in
		 * station/adhoc mode */
		/* The following may also be needed for other older chips */
		if (sc->sc_ah->hw_version.macVersion == AR_SREV_VERSION_9160)
			rfilt |= ATH9K_RX_FILTER_PROM;
		rfilt |= ATH9K_RX_FILTER_MCAST_BCAST_ALL;
	}

	return rfilt;

#undef RX_FILTER_PRESERVE
}

int ath_startrecv(struct ath_softc *sc)
{
	struct ath_hw *ah = sc->sc_ah;
	struct ath_buf *bf, *tbf;

	spin_lock_bh(&sc->rx.rxbuflock);
	if (list_empty(&sc->rx.rxbuf))
		goto start_recv;

	sc->rx.rxlink = NULL;
	list_for_each_entry_safe(bf, tbf, &sc->rx.rxbuf, list) {
		ath_rx_buf_link(sc, bf);
	}

	/* We could have deleted elements so the list may be empty now */
	if (list_empty(&sc->rx.rxbuf))
		goto start_recv;

	bf = list_first_entry(&sc->rx.rxbuf, struct ath_buf, list);
	ath9k_hw_putrxbuf(ah, bf->bf_daddr);
	ath9k_hw_rxena(ah);

start_recv:
	spin_unlock_bh(&sc->rx.rxbuflock);
	ath_opmode_init(sc);
	ath9k_hw_startpcureceive(ah);

	return 0;
}

bool ath_stoprecv(struct ath_softc *sc)
{
	struct ath_hw *ah = sc->sc_ah;
	bool stopped;

	ath9k_hw_stoppcurecv(ah);
	ath9k_hw_setrxfilter(ah, 0);
	stopped = ath9k_hw_stopdmarecv(ah);
	sc->rx.rxlink = NULL;

	return stopped;
}

void ath_flushrecv(struct ath_softc *sc)
{
	spin_lock_bh(&sc->rx.rxflushlock);
	sc->sc_flags |= SC_OP_RXFLUSH;
	ath_rx_tasklet(sc, 1);
	sc->sc_flags &= ~SC_OP_RXFLUSH;
	spin_unlock_bh(&sc->rx.rxflushlock);
}

static bool ath_beacon_dtim_pending_cab(struct sk_buff *skb)
{
	/* Check whether the Beacon frame has DTIM indicating buffered bc/mc */
	struct ieee80211_mgmt *mgmt;
	u8 *pos, *end, id, elen;
	struct ieee80211_tim_ie *tim;

	mgmt = (struct ieee80211_mgmt *)skb->data;
	pos = mgmt->u.beacon.variable;
	end = skb->data + skb->len;

	while (pos + 2 < end) {
		id = *pos++;
		elen = *pos++;
		if (pos + elen > end)
			break;

		if (id == WLAN_EID_TIM) {
			if (elen < sizeof(*tim))
				break;
			tim = (struct ieee80211_tim_ie *) pos;
			if (tim->dtim_count != 0)
				break;
			return tim->bitmap_ctrl & 0x01;
		}

		pos += elen;
	}

	return false;
}

static void ath_rx_ps_beacon(struct ath_softc *sc, struct sk_buff *skb)
{
	struct ieee80211_mgmt *mgmt;
	struct ath_common *common = ath9k_hw_common(sc->sc_ah);

	if (skb->len < 24 + 8 + 2 + 2)
		return;

	mgmt = (struct ieee80211_mgmt *)skb->data;
	if (memcmp(common->curbssid, mgmt->bssid, ETH_ALEN) != 0)
		return; /* not from our current AP */

	sc->ps_flags &= ~PS_WAIT_FOR_BEACON;

	if (sc->ps_flags & PS_BEACON_SYNC) {
		sc->ps_flags &= ~PS_BEACON_SYNC;
		ath_print(common, ATH_DBG_PS,
			  "Reconfigure Beacon timers based on "
			  "timestamp from the AP\n");
		ath_beacon_config(sc, NULL);
	}

	if (ath_beacon_dtim_pending_cab(skb)) {
		/*
		 * Remain awake waiting for buffered broadcast/multicast
		 * frames. If the last broadcast/multicast frame is not
		 * received properly, the next beacon frame will work as
		 * a backup trigger for returning into NETWORK SLEEP state,
		 * so we are waiting for it as well.
		 */
		ath_print(common, ATH_DBG_PS, "Received DTIM beacon indicating "
			  "buffered broadcast/multicast frame(s)\n");
		sc->ps_flags |= PS_WAIT_FOR_CAB | PS_WAIT_FOR_BEACON;
		return;
	}

	if (sc->ps_flags & PS_WAIT_FOR_CAB) {
		/*
		 * This can happen if a broadcast frame is dropped or the AP
		 * fails to send a frame indicating that all CAB frames have
		 * been delivered.
		 */
		sc->ps_flags &= ~PS_WAIT_FOR_CAB;
		ath_print(common, ATH_DBG_PS,
			  "PS wait for CAB frames timed out\n");
	}
}

static void ath_rx_ps(struct ath_softc *sc, struct sk_buff *skb)
{
	struct ieee80211_hdr *hdr;
	struct ath_common *common = ath9k_hw_common(sc->sc_ah);

	hdr = (struct ieee80211_hdr *)skb->data;

	/* Process Beacon and CAB receive in PS state */
	if ((sc->ps_flags & PS_WAIT_FOR_BEACON) &&
	    ieee80211_is_beacon(hdr->frame_control))
		ath_rx_ps_beacon(sc, skb);
	else if ((sc->ps_flags & PS_WAIT_FOR_CAB) &&
		 (ieee80211_is_data(hdr->frame_control) ||
		  ieee80211_is_action(hdr->frame_control)) &&
		 is_multicast_ether_addr(hdr->addr1) &&
		 !ieee80211_has_moredata(hdr->frame_control)) {
		/*
		 * No more broadcast/multicast frames to be received at this
		 * point.
		 */
		sc->ps_flags &= ~PS_WAIT_FOR_CAB;
		ath_print(common, ATH_DBG_PS,
			  "All PS CAB frames received, back to sleep\n");
	} else if ((sc->ps_flags & PS_WAIT_FOR_PSPOLL_DATA) &&
		   !is_multicast_ether_addr(hdr->addr1) &&
		   !ieee80211_has_morefrags(hdr->frame_control)) {
		sc->ps_flags &= ~PS_WAIT_FOR_PSPOLL_DATA;
		ath_print(common, ATH_DBG_PS,
			  "Going back to sleep after having received "
			  "PS-Poll data (0x%lx)\n",
			sc->ps_flags & (PS_WAIT_FOR_BEACON |
					PS_WAIT_FOR_CAB |
					PS_WAIT_FOR_PSPOLL_DATA |
					PS_WAIT_FOR_TX_ACK));
	}
}

static void ath_rx_send_to_mac80211(struct ieee80211_hw *hw,
				    struct ath_softc *sc, struct sk_buff *skb,
				    struct ieee80211_rx_status *rxs)
{
	struct ieee80211_hdr *hdr;

	hdr = (struct ieee80211_hdr *)skb->data;

	/* Send the frame to mac80211 */
	if (is_multicast_ether_addr(hdr->addr1)) {
		int i;
		/*
		 * Deliver broadcast/multicast frames to all suitable
		 * virtual wiphys.
		 */
		/* TODO: filter based on channel configuration */
		for (i = 0; i < sc->num_sec_wiphy; i++) {
			struct ath_wiphy *aphy = sc->sec_wiphy[i];
			struct sk_buff *nskb;
			if (aphy == NULL)
				continue;
			nskb = skb_copy(skb, GFP_ATOMIC);
			if (!nskb)
				continue;
			ieee80211_rx(aphy->hw, nskb);
		}
		ieee80211_rx(sc->hw, skb);
	} else
		/* Deliver unicast frames based on receiver address */
		ieee80211_rx(hw, skb);
}

int ath_rx_tasklet(struct ath_softc *sc, int flush)
{
#define PA2DESC(_sc, _pa)                                               \
	((struct ath_desc *)((caddr_t)(_sc)->rx.rxdma.dd_desc +		\
			     ((_pa) - (_sc)->rx.rxdma.dd_desc_paddr)))

	struct ath_buf *bf;
	struct ath_desc *ds;
	struct ath_rx_status *rx_stats;
	struct sk_buff *skb = NULL, *requeue_skb;
	struct ieee80211_rx_status *rxs;
	struct ath_hw *ah = sc->sc_ah;
	struct ath_common *common = ath9k_hw_common(ah);
	/*
	 * The hw can techncically differ from common->hw when using ath9k
	 * virtual wiphy so to account for that we iterate over the active
	 * wiphys and find the appropriate wiphy and therefore hw.
	 */
	struct ieee80211_hw *hw = NULL;
	struct ieee80211_hdr *hdr;
	int retval;
	bool decrypt_error = false;

	spin_lock_bh(&sc->rx.rxbuflock);

	do {
		/* If handling rx interrupt and flush is in progress => exit */
		if ((sc->sc_flags & SC_OP_RXFLUSH) && (flush == 0))
			break;

		if (list_empty(&sc->rx.rxbuf)) {
			sc->rx.rxlink = NULL;
			break;
		}

		bf = list_first_entry(&sc->rx.rxbuf, struct ath_buf, list);
		ds = bf->bf_desc;

		/*
		 * Must provide the virtual address of the current
		 * descriptor, the physical address, and the virtual
		 * address of the next descriptor in the h/w chain.
		 * This allows the HAL to look ahead to see if the
		 * hardware is done with a descriptor by checking the
		 * done bit in the following descriptor and the address
		 * of the current descriptor the DMA engine is working
		 * on.  All this is necessary because of our use of
		 * a self-linked list to avoid rx overruns.
		 */
		retval = ath9k_hw_rxprocdesc(ah, ds,
					     bf->bf_daddr,
					     PA2DESC(sc, ds->ds_link),
					     0);
		if (retval == -EINPROGRESS) {
			struct ath_buf *tbf;
			struct ath_desc *tds;

			if (list_is_last(&bf->list, &sc->rx.rxbuf)) {
				sc->rx.rxlink = NULL;
				break;
			}

			tbf = list_entry(bf->list.next, struct ath_buf, list);

			/*
			 * On some hardware the descriptor status words could
			 * get corrupted, including the done bit. Because of
			 * this, check if the next descriptor's done bit is
			 * set or not.
			 *
			 * If the next descriptor's done bit is set, the current
			 * descriptor has been corrupted. Force s/w to discard
			 * this descriptor and continue...
			 */

			tds = tbf->bf_desc;
			retval = ath9k_hw_rxprocdesc(ah, tds, tbf->bf_daddr,
					     PA2DESC(sc, tds->ds_link), 0);
			if (retval == -EINPROGRESS) {
				break;
			}
		}

		skb = bf->bf_mpdu;
		if (!skb)
			continue;

		/*
		 * Synchronize the DMA transfer with CPU before
		 * 1. accessing the frame
		 * 2. requeueing the same buffer to h/w
		 */
		dma_sync_single_for_cpu(sc->dev, bf->bf_buf_addr,
				common->rx_bufsize,
				DMA_FROM_DEVICE);

		hdr = (struct ieee80211_hdr *) skb->data;
		rxs =  IEEE80211_SKB_RXCB(skb);

		hw = ath_get_virt_hw(sc, hdr);
		rx_stats = &ds->ds_rxstat;

		ath_debug_stat_rx(sc, bf);

		/*
		 * If we're asked to flush receive queue, directly
		 * chain it back at the queue without processing it.
		 */
		if (flush)
			goto requeue;

		retval = ath9k_cmn_rx_skb_preprocess(common, hw, skb, rx_stats,
						     rxs, &decrypt_error);
		if (retval)
			goto requeue;

		/* Ensure we always have an skb to requeue once we are done
		 * processing the current buffer's skb */
		requeue_skb = ath_rxbuf_alloc(common, common->rx_bufsize, GFP_ATOMIC);

		/* If there is no memory we ignore the current RX'd frame,
		 * tell hardware it can give us a new frame using the old
		 * skb and put it at the tail of the sc->rx.rxbuf list for
		 * processing. */
		if (!requeue_skb)
			goto requeue;

		/* Unmap the frame */
		dma_unmap_single(sc->dev, bf->bf_buf_addr,
				 common->rx_bufsize,
				 DMA_FROM_DEVICE);

		skb_put(skb, rx_stats->rs_datalen);

		ath9k_cmn_rx_skb_postprocess(common, skb, rx_stats,
					     rxs, decrypt_error);

		/* We will now give hardware our shiny new allocated skb */
		bf->bf_mpdu = requeue_skb;
		bf->bf_buf_addr = dma_map_single(sc->dev, requeue_skb->data,
						 common->rx_bufsize,
						 DMA_FROM_DEVICE);
		if (unlikely(dma_mapping_error(sc->dev,
			  bf->bf_buf_addr))) {
			dev_kfree_skb_any(requeue_skb);
			bf->bf_mpdu = NULL;
			ath_print(common, ATH_DBG_FATAL,
				  "dma_mapping_error() on RX\n");
			ath_rx_send_to_mac80211(hw, sc, skb, rxs);
			break;
		}
		bf->bf_dmacontext = bf->bf_buf_addr;

		/*
		 * change the default rx antenna if rx diversity chooses the
		 * other antenna 3 times in a row.
		 */
		if (sc->rx.defant != ds->ds_rxstat.rs_antenna) {
			if (++sc->rx.rxotherant >= 3)
				ath_setdefantenna(sc, rx_stats->rs_antenna);
		} else {
			sc->rx.rxotherant = 0;
		}

		if (unlikely(sc->ps_flags & (PS_WAIT_FOR_BEACON |
					     PS_WAIT_FOR_CAB |
					     PS_WAIT_FOR_PSPOLL_DATA)))
			ath_rx_ps(sc, skb);

		ath_rx_send_to_mac80211(hw, sc, skb, rxs);

requeue:
		list_move_tail(&bf->list, &sc->rx.rxbuf);
		ath_rx_buf_link(sc, bf);
	} while (1);

	spin_unlock_bh(&sc->rx.rxbuflock);

	return 0;
#undef PA2DESC
}