xref: /openbmc/linux/drivers/net/ethernet/sfc/siena/nic.c (revision f029c781)
1 // SPDX-License-Identifier: GPL-2.0-only
2 /****************************************************************************
3  * Driver for Solarflare network controllers and boards
4  * Copyright 2005-2006 Fen Systems Ltd.
5  * Copyright 2006-2013 Solarflare Communications Inc.
6  */
7 
8 #include <linux/bitops.h>
9 #include <linux/delay.h>
10 #include <linux/interrupt.h>
11 #include <linux/pci.h>
12 #include <linux/module.h>
13 #include <linux/seq_file.h>
14 #include <linux/cpu_rmap.h>
15 #include "net_driver.h"
16 #include "bitfield.h"
17 #include "efx.h"
18 #include "nic.h"
19 #include "farch_regs.h"
20 #include "io.h"
21 #include "workarounds.h"
22 #include "mcdi_pcol.h"
23 
24 /**************************************************************************
25  *
26  * Generic buffer handling
27  * These buffers are used for interrupt status, MAC stats, etc.
28  *
29  **************************************************************************/
30 
efx_siena_alloc_buffer(struct efx_nic * efx,struct efx_buffer * buffer,unsigned int len,gfp_t gfp_flags)31 int efx_siena_alloc_buffer(struct efx_nic *efx, struct efx_buffer *buffer,
32 			   unsigned int len, gfp_t gfp_flags)
33 {
34 	buffer->addr = dma_alloc_coherent(&efx->pci_dev->dev, len,
35 					  &buffer->dma_addr, gfp_flags);
36 	if (!buffer->addr)
37 		return -ENOMEM;
38 	buffer->len = len;
39 	return 0;
40 }
41 
efx_siena_free_buffer(struct efx_nic * efx,struct efx_buffer * buffer)42 void efx_siena_free_buffer(struct efx_nic *efx, struct efx_buffer *buffer)
43 {
44 	if (buffer->addr) {
45 		dma_free_coherent(&efx->pci_dev->dev, buffer->len,
46 				  buffer->addr, buffer->dma_addr);
47 		buffer->addr = NULL;
48 	}
49 }
50 
51 /* Check whether an event is present in the eventq at the current
52  * read pointer.  Only useful for self-test.
53  */
efx_siena_event_present(struct efx_channel * channel)54 bool efx_siena_event_present(struct efx_channel *channel)
55 {
56 	return efx_event_present(efx_event(channel, channel->eventq_read_ptr));
57 }
58 
efx_siena_event_test_start(struct efx_channel * channel)59 void efx_siena_event_test_start(struct efx_channel *channel)
60 {
61 	channel->event_test_cpu = -1;
62 	smp_wmb();
63 	channel->efx->type->ev_test_generate(channel);
64 }
65 
efx_siena_irq_test_start(struct efx_nic * efx)66 int efx_siena_irq_test_start(struct efx_nic *efx)
67 {
68 	efx->last_irq_cpu = -1;
69 	smp_wmb();
70 	return efx->type->irq_test_generate(efx);
71 }
72 
73 /* Hook interrupt handler(s)
74  * Try MSI and then legacy interrupts.
75  */
efx_siena_init_interrupt(struct efx_nic * efx)76 int efx_siena_init_interrupt(struct efx_nic *efx)
77 {
78 	struct efx_channel *channel;
79 	unsigned int n_irqs;
80 	int rc;
81 
82 	if (!EFX_INT_MODE_USE_MSI(efx)) {
83 		rc = request_irq(efx->legacy_irq,
84 				 efx->type->irq_handle_legacy, IRQF_SHARED,
85 				 efx->name, efx);
86 		if (rc) {
87 			netif_err(efx, drv, efx->net_dev,
88 				  "failed to hook legacy IRQ %d\n",
89 				  efx->pci_dev->irq);
90 			goto fail1;
91 		}
92 		efx->irqs_hooked = true;
93 		return 0;
94 	}
95 
96 #ifdef CONFIG_RFS_ACCEL
97 	if (efx->interrupt_mode == EFX_INT_MODE_MSIX) {
98 		efx->net_dev->rx_cpu_rmap =
99 			alloc_irq_cpu_rmap(efx->n_rx_channels);
100 		if (!efx->net_dev->rx_cpu_rmap) {
101 			rc = -ENOMEM;
102 			goto fail1;
103 		}
104 	}
105 #endif
106 
107 	/* Hook MSI or MSI-X interrupt */
108 	n_irqs = 0;
109 	efx_for_each_channel(channel, efx) {
110 		rc = request_irq(channel->irq, efx->type->irq_handle_msi,
111 				 IRQF_PROBE_SHARED, /* Not shared */
112 				 efx->msi_context[channel->channel].name,
113 				 &efx->msi_context[channel->channel]);
114 		if (rc) {
115 			netif_err(efx, drv, efx->net_dev,
116 				  "failed to hook IRQ %d\n", channel->irq);
117 			goto fail2;
118 		}
119 		++n_irqs;
120 
121 #ifdef CONFIG_RFS_ACCEL
122 		if (efx->interrupt_mode == EFX_INT_MODE_MSIX &&
123 		    channel->channel < efx->n_rx_channels) {
124 			rc = irq_cpu_rmap_add(efx->net_dev->rx_cpu_rmap,
125 					      channel->irq);
126 			if (rc)
127 				goto fail2;
128 		}
129 #endif
130 	}
131 
132 	efx->irqs_hooked = true;
133 	return 0;
134 
135  fail2:
136 #ifdef CONFIG_RFS_ACCEL
137 	free_irq_cpu_rmap(efx->net_dev->rx_cpu_rmap);
138 	efx->net_dev->rx_cpu_rmap = NULL;
139 #endif
140 	efx_for_each_channel(channel, efx) {
141 		if (n_irqs-- == 0)
142 			break;
143 		free_irq(channel->irq, &efx->msi_context[channel->channel]);
144 	}
145  fail1:
146 	return rc;
147 }
148 
efx_siena_fini_interrupt(struct efx_nic * efx)149 void efx_siena_fini_interrupt(struct efx_nic *efx)
150 {
151 	struct efx_channel *channel;
152 
153 #ifdef CONFIG_RFS_ACCEL
154 	free_irq_cpu_rmap(efx->net_dev->rx_cpu_rmap);
155 	efx->net_dev->rx_cpu_rmap = NULL;
156 #endif
157 
158 	if (!efx->irqs_hooked)
159 		return;
160 	if (EFX_INT_MODE_USE_MSI(efx)) {
161 		/* Disable MSI/MSI-X interrupts */
162 		efx_for_each_channel(channel, efx)
163 			free_irq(channel->irq,
164 				 &efx->msi_context[channel->channel]);
165 	} else {
166 		/* Disable legacy interrupt */
167 		free_irq(efx->legacy_irq, efx);
168 	}
169 	efx->irqs_hooked = false;
170 }
171 
172 /* Register dump */
173 
174 #define REGISTER_REVISION_FA	1
175 #define REGISTER_REVISION_FB	2
176 #define REGISTER_REVISION_FC	3
177 #define REGISTER_REVISION_FZ	3	/* last Falcon arch revision */
178 #define REGISTER_REVISION_ED	4
179 #define REGISTER_REVISION_EZ	4	/* latest EF10 revision */
180 
181 struct efx_nic_reg {
182 	u32 offset:24;
183 	u32 min_revision:3, max_revision:3;
184 };
185 
186 #define REGISTER(name, arch, min_rev, max_rev) {			\
187 	arch ## R_ ## min_rev ## max_rev ## _ ## name,			\
188 	REGISTER_REVISION_ ## arch ## min_rev,				\
189 	REGISTER_REVISION_ ## arch ## max_rev				\
190 }
191 #define REGISTER_AA(name) REGISTER(name, F, A, A)
192 #define REGISTER_AB(name) REGISTER(name, F, A, B)
193 #define REGISTER_AZ(name) REGISTER(name, F, A, Z)
194 #define REGISTER_BB(name) REGISTER(name, F, B, B)
195 #define REGISTER_BZ(name) REGISTER(name, F, B, Z)
196 #define REGISTER_CZ(name) REGISTER(name, F, C, Z)
197 
198 static const struct efx_nic_reg efx_nic_regs[] = {
199 	REGISTER_AZ(ADR_REGION),
200 	REGISTER_AZ(INT_EN_KER),
201 	REGISTER_BZ(INT_EN_CHAR),
202 	REGISTER_AZ(INT_ADR_KER),
203 	REGISTER_BZ(INT_ADR_CHAR),
204 	/* INT_ACK_KER is WO */
205 	/* INT_ISR0 is RC */
206 	REGISTER_AZ(HW_INIT),
207 	REGISTER_CZ(USR_EV_CFG),
208 	REGISTER_AB(EE_SPI_HCMD),
209 	REGISTER_AB(EE_SPI_HADR),
210 	REGISTER_AB(EE_SPI_HDATA),
211 	REGISTER_AB(EE_BASE_PAGE),
212 	REGISTER_AB(EE_VPD_CFG0),
213 	/* EE_VPD_SW_CNTL and EE_VPD_SW_DATA are not used */
214 	/* PMBX_DBG_IADDR and PBMX_DBG_IDATA are indirect */
215 	/* PCIE_CORE_INDIRECT is indirect */
216 	REGISTER_AB(NIC_STAT),
217 	REGISTER_AB(GPIO_CTL),
218 	REGISTER_AB(GLB_CTL),
219 	/* FATAL_INTR_KER and FATAL_INTR_CHAR are partly RC */
220 	REGISTER_BZ(DP_CTRL),
221 	REGISTER_AZ(MEM_STAT),
222 	REGISTER_AZ(CS_DEBUG),
223 	REGISTER_AZ(ALTERA_BUILD),
224 	REGISTER_AZ(CSR_SPARE),
225 	REGISTER_AB(PCIE_SD_CTL0123),
226 	REGISTER_AB(PCIE_SD_CTL45),
227 	REGISTER_AB(PCIE_PCS_CTL_STAT),
228 	/* DEBUG_DATA_OUT is not used */
229 	/* DRV_EV is WO */
230 	REGISTER_AZ(EVQ_CTL),
231 	REGISTER_AZ(EVQ_CNT1),
232 	REGISTER_AZ(EVQ_CNT2),
233 	REGISTER_AZ(BUF_TBL_CFG),
234 	REGISTER_AZ(SRM_RX_DC_CFG),
235 	REGISTER_AZ(SRM_TX_DC_CFG),
236 	REGISTER_AZ(SRM_CFG),
237 	/* BUF_TBL_UPD is WO */
238 	REGISTER_AZ(SRM_UPD_EVQ),
239 	REGISTER_AZ(SRAM_PARITY),
240 	REGISTER_AZ(RX_CFG),
241 	REGISTER_BZ(RX_FILTER_CTL),
242 	/* RX_FLUSH_DESCQ is WO */
243 	REGISTER_AZ(RX_DC_CFG),
244 	REGISTER_AZ(RX_DC_PF_WM),
245 	REGISTER_BZ(RX_RSS_TKEY),
246 	/* RX_NODESC_DROP is RC */
247 	REGISTER_AA(RX_SELF_RST),
248 	/* RX_DEBUG, RX_PUSH_DROP are not used */
249 	REGISTER_CZ(RX_RSS_IPV6_REG1),
250 	REGISTER_CZ(RX_RSS_IPV6_REG2),
251 	REGISTER_CZ(RX_RSS_IPV6_REG3),
252 	/* TX_FLUSH_DESCQ is WO */
253 	REGISTER_AZ(TX_DC_CFG),
254 	REGISTER_AA(TX_CHKSM_CFG),
255 	REGISTER_AZ(TX_CFG),
256 	/* TX_PUSH_DROP is not used */
257 	REGISTER_AZ(TX_RESERVED),
258 	REGISTER_BZ(TX_PACE),
259 	/* TX_PACE_DROP_QID is RC */
260 	REGISTER_BB(TX_VLAN),
261 	REGISTER_BZ(TX_IPFIL_PORTEN),
262 	REGISTER_AB(MD_TXD),
263 	REGISTER_AB(MD_RXD),
264 	REGISTER_AB(MD_CS),
265 	REGISTER_AB(MD_PHY_ADR),
266 	REGISTER_AB(MD_ID),
267 	/* MD_STAT is RC */
268 	REGISTER_AB(MAC_STAT_DMA),
269 	REGISTER_AB(MAC_CTRL),
270 	REGISTER_BB(GEN_MODE),
271 	REGISTER_AB(MAC_MC_HASH_REG0),
272 	REGISTER_AB(MAC_MC_HASH_REG1),
273 	REGISTER_AB(GM_CFG1),
274 	REGISTER_AB(GM_CFG2),
275 	/* GM_IPG and GM_HD are not used */
276 	REGISTER_AB(GM_MAX_FLEN),
277 	/* GM_TEST is not used */
278 	REGISTER_AB(GM_ADR1),
279 	REGISTER_AB(GM_ADR2),
280 	REGISTER_AB(GMF_CFG0),
281 	REGISTER_AB(GMF_CFG1),
282 	REGISTER_AB(GMF_CFG2),
283 	REGISTER_AB(GMF_CFG3),
284 	REGISTER_AB(GMF_CFG4),
285 	REGISTER_AB(GMF_CFG5),
286 	REGISTER_BB(TX_SRC_MAC_CTL),
287 	REGISTER_AB(XM_ADR_LO),
288 	REGISTER_AB(XM_ADR_HI),
289 	REGISTER_AB(XM_GLB_CFG),
290 	REGISTER_AB(XM_TX_CFG),
291 	REGISTER_AB(XM_RX_CFG),
292 	REGISTER_AB(XM_MGT_INT_MASK),
293 	REGISTER_AB(XM_FC),
294 	REGISTER_AB(XM_PAUSE_TIME),
295 	REGISTER_AB(XM_TX_PARAM),
296 	REGISTER_AB(XM_RX_PARAM),
297 	/* XM_MGT_INT_MSK (note no 'A') is RC */
298 	REGISTER_AB(XX_PWR_RST),
299 	REGISTER_AB(XX_SD_CTL),
300 	REGISTER_AB(XX_TXDRV_CTL),
301 	/* XX_PRBS_CTL, XX_PRBS_CHK and XX_PRBS_ERR are not used */
302 	/* XX_CORE_STAT is partly RC */
303 };
304 
305 struct efx_nic_reg_table {
306 	u32 offset:24;
307 	u32 min_revision:3, max_revision:3;
308 	u32 step:6, rows:21;
309 };
310 
311 #define REGISTER_TABLE_DIMENSIONS(_, offset, arch, min_rev, max_rev, step, rows) { \
312 	offset,								\
313 	REGISTER_REVISION_ ## arch ## min_rev,				\
314 	REGISTER_REVISION_ ## arch ## max_rev,				\
315 	step, rows							\
316 }
317 #define REGISTER_TABLE(name, arch, min_rev, max_rev)			\
318 	REGISTER_TABLE_DIMENSIONS(					\
319 		name, arch ## R_ ## min_rev ## max_rev ## _ ## name,	\
320 		arch, min_rev, max_rev,					\
321 		arch ## R_ ## min_rev ## max_rev ## _ ## name ## _STEP,	\
322 		arch ## R_ ## min_rev ## max_rev ## _ ## name ## _ROWS)
323 #define REGISTER_TABLE_AA(name) REGISTER_TABLE(name, F, A, A)
324 #define REGISTER_TABLE_AZ(name) REGISTER_TABLE(name, F, A, Z)
325 #define REGISTER_TABLE_BB(name) REGISTER_TABLE(name, F, B, B)
326 #define REGISTER_TABLE_BZ(name) REGISTER_TABLE(name, F, B, Z)
327 #define REGISTER_TABLE_BB_CZ(name)					\
328 	REGISTER_TABLE_DIMENSIONS(name, FR_BZ_ ## name, F, B, B,	\
329 				  FR_BZ_ ## name ## _STEP,		\
330 				  FR_BB_ ## name ## _ROWS),		\
331 	REGISTER_TABLE_DIMENSIONS(name, FR_BZ_ ## name, F, C, Z,	\
332 				  FR_BZ_ ## name ## _STEP,		\
333 				  FR_CZ_ ## name ## _ROWS)
334 #define REGISTER_TABLE_CZ(name) REGISTER_TABLE(name, F, C, Z)
335 
336 static const struct efx_nic_reg_table efx_nic_reg_tables[] = {
337 	/* DRIVER is not used */
338 	/* EVQ_RPTR, TIMER_COMMAND, USR_EV and {RX,TX}_DESC_UPD are WO */
339 	REGISTER_TABLE_BB(TX_IPFIL_TBL),
340 	REGISTER_TABLE_BB(TX_SRC_MAC_TBL),
341 	REGISTER_TABLE_AA(RX_DESC_PTR_TBL_KER),
342 	REGISTER_TABLE_BB_CZ(RX_DESC_PTR_TBL),
343 	REGISTER_TABLE_AA(TX_DESC_PTR_TBL_KER),
344 	REGISTER_TABLE_BB_CZ(TX_DESC_PTR_TBL),
345 	REGISTER_TABLE_AA(EVQ_PTR_TBL_KER),
346 	REGISTER_TABLE_BB_CZ(EVQ_PTR_TBL),
347 	/* We can't reasonably read all of the buffer table (up to 8MB!).
348 	 * However this driver will only use a few entries.  Reading
349 	 * 1K entries allows for some expansion of queue count and
350 	 * size before we need to change the version. */
351 	REGISTER_TABLE_DIMENSIONS(BUF_FULL_TBL_KER, FR_AA_BUF_FULL_TBL_KER,
352 				  F, A, A, 8, 1024),
353 	REGISTER_TABLE_DIMENSIONS(BUF_FULL_TBL, FR_BZ_BUF_FULL_TBL,
354 				  F, B, Z, 8, 1024),
355 	REGISTER_TABLE_CZ(RX_MAC_FILTER_TBL0),
356 	REGISTER_TABLE_BB_CZ(TIMER_TBL),
357 	REGISTER_TABLE_BB_CZ(TX_PACE_TBL),
358 	REGISTER_TABLE_BZ(RX_INDIRECTION_TBL),
359 	/* TX_FILTER_TBL0 is huge and not used by this driver */
360 	REGISTER_TABLE_CZ(TX_MAC_FILTER_TBL0),
361 	REGISTER_TABLE_CZ(MC_TREG_SMEM),
362 	/* MSIX_PBA_TABLE is not mapped */
363 	/* SRM_DBG is not mapped (and is redundant with BUF_FLL_TBL) */
364 	REGISTER_TABLE_BZ(RX_FILTER_TBL0),
365 };
366 
efx_siena_get_regs_len(struct efx_nic * efx)367 size_t efx_siena_get_regs_len(struct efx_nic *efx)
368 {
369 	const struct efx_nic_reg *reg;
370 	const struct efx_nic_reg_table *table;
371 	size_t len = 0;
372 
373 	for (reg = efx_nic_regs;
374 	     reg < efx_nic_regs + ARRAY_SIZE(efx_nic_regs);
375 	     reg++)
376 		if (efx->type->revision >= reg->min_revision &&
377 		    efx->type->revision <= reg->max_revision)
378 			len += sizeof(efx_oword_t);
379 
380 	for (table = efx_nic_reg_tables;
381 	     table < efx_nic_reg_tables + ARRAY_SIZE(efx_nic_reg_tables);
382 	     table++)
383 		if (efx->type->revision >= table->min_revision &&
384 		    efx->type->revision <= table->max_revision)
385 			len += table->rows * min_t(size_t, table->step, 16);
386 
387 	return len;
388 }
389 
efx_siena_get_regs(struct efx_nic * efx,void * buf)390 void efx_siena_get_regs(struct efx_nic *efx, void *buf)
391 {
392 	const struct efx_nic_reg *reg;
393 	const struct efx_nic_reg_table *table;
394 
395 	for (reg = efx_nic_regs;
396 	     reg < efx_nic_regs + ARRAY_SIZE(efx_nic_regs);
397 	     reg++) {
398 		if (efx->type->revision >= reg->min_revision &&
399 		    efx->type->revision <= reg->max_revision) {
400 			efx_reado(efx, (efx_oword_t *)buf, reg->offset);
401 			buf += sizeof(efx_oword_t);
402 		}
403 	}
404 
405 	for (table = efx_nic_reg_tables;
406 	     table < efx_nic_reg_tables + ARRAY_SIZE(efx_nic_reg_tables);
407 	     table++) {
408 		size_t size, i;
409 
410 		if (!(efx->type->revision >= table->min_revision &&
411 		      efx->type->revision <= table->max_revision))
412 			continue;
413 
414 		size = min_t(size_t, table->step, 16);
415 
416 		for (i = 0; i < table->rows; i++) {
417 			switch (table->step) {
418 			case 4: /* 32-bit SRAM */
419 				efx_readd(efx, buf, table->offset + 4 * i);
420 				break;
421 			case 8: /* 64-bit SRAM */
422 				efx_sram_readq(efx,
423 					       efx->membase + table->offset,
424 					       buf, i);
425 				break;
426 			case 16: /* 128-bit-readable register */
427 				efx_reado_table(efx, buf, table->offset, i);
428 				break;
429 			case 32: /* 128-bit register, interleaved */
430 				efx_reado_table(efx, buf, table->offset, 2 * i);
431 				break;
432 			default:
433 				WARN_ON(1);
434 				return;
435 			}
436 			buf += size;
437 		}
438 	}
439 }
440 
441 /**
442  * efx_siena_describe_stats - Describe supported statistics for ethtool
443  * @desc: Array of &struct efx_hw_stat_desc describing the statistics
444  * @count: Length of the @desc array
445  * @mask: Bitmask of which elements of @desc are enabled
446  * @names: Buffer to copy names to, or %NULL.  The names are copied
447  *	starting at intervals of %ETH_GSTRING_LEN bytes.
448  *
449  * Returns the number of visible statistics, i.e. the number of set
450  * bits in the first @count bits of @mask for which a name is defined.
451  */
efx_siena_describe_stats(const struct efx_hw_stat_desc * desc,size_t count,const unsigned long * mask,u8 * names)452 size_t efx_siena_describe_stats(const struct efx_hw_stat_desc *desc, size_t count,
453 				const unsigned long *mask, u8 *names)
454 {
455 	size_t visible = 0;
456 	size_t index;
457 
458 	for_each_set_bit(index, mask, count) {
459 		if (desc[index].name) {
460 			if (names) {
461 				strscpy(names, desc[index].name,
462 					ETH_GSTRING_LEN);
463 				names += ETH_GSTRING_LEN;
464 			}
465 			++visible;
466 		}
467 	}
468 
469 	return visible;
470 }
471 
472 /**
473  * efx_siena_update_stats - Convert statistics DMA buffer to array of u64
474  * @desc: Array of &struct efx_hw_stat_desc describing the DMA buffer
475  *	layout.  DMA widths of 0, 16, 32 and 64 are supported; where
476  *	the width is specified as 0 the corresponding element of
477  *	@stats is not updated.
478  * @count: Length of the @desc array
479  * @mask: Bitmask of which elements of @desc are enabled
480  * @stats: Buffer to update with the converted statistics.  The length
481  *	of this array must be at least @count.
482  * @dma_buf: DMA buffer containing hardware statistics
483  * @accumulate: If set, the converted values will be added rather than
484  *	directly stored to the corresponding elements of @stats
485  */
efx_siena_update_stats(const struct efx_hw_stat_desc * desc,size_t count,const unsigned long * mask,u64 * stats,const void * dma_buf,bool accumulate)486 void efx_siena_update_stats(const struct efx_hw_stat_desc *desc, size_t count,
487 			    const unsigned long *mask,
488 			    u64 *stats, const void *dma_buf, bool accumulate)
489 {
490 	size_t index;
491 
492 	for_each_set_bit(index, mask, count) {
493 		if (desc[index].dma_width) {
494 			const void *addr = dma_buf + desc[index].offset;
495 			u64 val;
496 
497 			switch (desc[index].dma_width) {
498 			case 16:
499 				val = le16_to_cpup((__le16 *)addr);
500 				break;
501 			case 32:
502 				val = le32_to_cpup((__le32 *)addr);
503 				break;
504 			case 64:
505 				val = le64_to_cpup((__le64 *)addr);
506 				break;
507 			default:
508 				WARN_ON(1);
509 				val = 0;
510 				break;
511 			}
512 
513 			if (accumulate)
514 				stats[index] += val;
515 			else
516 				stats[index] = val;
517 		}
518 	}
519 }
520 
efx_siena_fix_nodesc_drop_stat(struct efx_nic * efx,u64 * rx_nodesc_drops)521 void efx_siena_fix_nodesc_drop_stat(struct efx_nic *efx, u64 *rx_nodesc_drops)
522 {
523 	/* if down, or this is the first update after coming up */
524 	if (!(efx->net_dev->flags & IFF_UP) || !efx->rx_nodesc_drops_prev_state)
525 		efx->rx_nodesc_drops_while_down +=
526 			*rx_nodesc_drops - efx->rx_nodesc_drops_total;
527 	efx->rx_nodesc_drops_total = *rx_nodesc_drops;
528 	efx->rx_nodesc_drops_prev_state = !!(efx->net_dev->flags & IFF_UP);
529 	*rx_nodesc_drops -= efx->rx_nodesc_drops_while_down;
530 }
531