drivers/net/ethernet/sfc/nic.c

   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 "ef10_regs.h"
  20 #include "farch_regs.h"
  21 #include "io.h"
  22 #include "workarounds.h"
  23
  24 /**************************************************************************
  25  *
  26  * Generic buffer handling
  27  * These buffers are used for interrupt status, MAC stats, etc.
  28  *
  29  **************************************************************************/
  30
  31 int efx_nic_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
  42 void efx_nic_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  */
  54 bool efx_nic_event_present(struct efx_channel *channel)
  55 {
  56         return efx_event_present(efx_event(channel, channel->eventq_read_ptr));
  57 }
  58
  59 void efx_nic_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
  66 int efx_nic_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  */
  76 int efx_nic_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                 return 0;
  93         }
  94
  95 #ifdef CONFIG_RFS_ACCEL
  96         if (efx->interrupt_mode == EFX_INT_MODE_MSIX) {
  97                 efx->net_dev->rx_cpu_rmap =
  98                         alloc_irq_cpu_rmap(efx->n_rx_channels);
  99                 if (!efx->net_dev->rx_cpu_rmap) {
 100                         rc = -ENOMEM;
 101                         goto fail1;
 102                 }
 103         }
 104 #endif
 105
 106         /* Hook MSI or MSI-X interrupt */
 107         n_irqs = 0;
 108         efx_for_each_channel(channel, efx) {
 109                 rc = request_irq(channel->irq, efx->type->irq_handle_msi,
 110                                  IRQF_PROBE_SHARED, /* Not shared */
 111                                  efx->msi_context[channel->channel].name,
 112                                  &efx->msi_context[channel->channel]);
 113                 if (rc) {
 114                         netif_err(efx, drv, efx->net_dev,
 115                                   "failed to hook IRQ %d\n", channel->irq);
 116                         goto fail2;
 117                 }
 118                 ++n_irqs;
 119
 120 #ifdef CONFIG_RFS_ACCEL
 121                 if (efx->interrupt_mode == EFX_INT_MODE_MSIX &&
 122                     channel->channel < efx->n_rx_channels) {
 123                         rc = irq_cpu_rmap_add(efx->net_dev->rx_cpu_rmap,
 124                                               channel->irq);
 125                         if (rc)
 126                                 goto fail2;
 127                 }
 128 #endif
 129         }
 130
 131         return 0;
 132
 133  fail2:
 134 #ifdef CONFIG_RFS_ACCEL
 135         free_irq_cpu_rmap(efx->net_dev->rx_cpu_rmap);
 136         efx->net_dev->rx_cpu_rmap = NULL;
 137 #endif
 138         efx_for_each_channel(channel, efx) {
 139                 if (n_irqs-- == 0)
 140                         break;
 141                 free_irq(channel->irq, &efx->msi_context[channel->channel]);
 142         }
 143  fail1:
 144         return rc;
 145 }
 146
 147 void efx_nic_fini_interrupt(struct efx_nic *efx)
 148 {
 149         struct efx_channel *channel;
 150
 151 #ifdef CONFIG_RFS_ACCEL
 152         free_irq_cpu_rmap(efx->net_dev->rx_cpu_rmap);
 153         efx->net_dev->rx_cpu_rmap = NULL;
 154 #endif
 155
 156         if (EFX_INT_MODE_USE_MSI(efx)) {
 157                 /* Disable MSI/MSI-X interrupts */
 158                 efx_for_each_channel(channel, efx)
 159                         free_irq(channel->irq,
 160                                  &efx->msi_context[channel->channel]);
 161         } else {
 162                 /* Disable legacy interrupt */
 163                 free_irq(efx->legacy_irq, efx);
 164         }
 165 }
 166
 167 /* Register dump */
 168
 169 #define REGISTER_REVISION_FA    1
 170 #define REGISTER_REVISION_FB    2
 171 #define REGISTER_REVISION_FC    3
 172 #define REGISTER_REVISION_FZ    3       /* last Falcon arch revision */
 173 #define REGISTER_REVISION_ED    4
 174 #define REGISTER_REVISION_EZ    4       /* latest EF10 revision */
 175
 176 struct efx_nic_reg {
 177         u32 offset:24;
 178         u32 min_revision:3, max_revision:3;
 179 };
 180
 181 #define REGISTER(name, arch, min_rev, max_rev) {                        \
 182         arch ## R_ ## min_rev ## max_rev ## _ ## name,                  \
 183         REGISTER_REVISION_ ## arch ## min_rev,                          \
 184         REGISTER_REVISION_ ## arch ## max_rev                           \
 185 }
 186 #define REGISTER_AA(name) REGISTER(name, F, A, A)
 187 #define REGISTER_AB(name) REGISTER(name, F, A, B)
 188 #define REGISTER_AZ(name) REGISTER(name, F, A, Z)
 189 #define REGISTER_BB(name) REGISTER(name, F, B, B)
 190 #define REGISTER_BZ(name) REGISTER(name, F, B, Z)
 191 #define REGISTER_CZ(name) REGISTER(name, F, C, Z)
 192 #define REGISTER_DZ(name) REGISTER(name, E, D, Z)
 193
 194 static const struct efx_nic_reg efx_nic_regs[] = {
 195         REGISTER_AZ(ADR_REGION),
 196         REGISTER_AZ(INT_EN_KER),
 197         REGISTER_BZ(INT_EN_CHAR),
 198         REGISTER_AZ(INT_ADR_KER),
 199         REGISTER_BZ(INT_ADR_CHAR),
 200         /* INT_ACK_KER is WO */
 201         /* INT_ISR0 is RC */
 202         REGISTER_AZ(HW_INIT),
 203         REGISTER_CZ(USR_EV_CFG),
 204         REGISTER_AB(EE_SPI_HCMD),
 205         REGISTER_AB(EE_SPI_HADR),
 206         REGISTER_AB(EE_SPI_HDATA),
 207         REGISTER_AB(EE_BASE_PAGE),
 208         REGISTER_AB(EE_VPD_CFG0),
 209         /* EE_VPD_SW_CNTL and EE_VPD_SW_DATA are not used */
 210         /* PMBX_DBG_IADDR and PBMX_DBG_IDATA are indirect */
 211         /* PCIE_CORE_INDIRECT is indirect */
 212         REGISTER_AB(NIC_STAT),
 213         REGISTER_AB(GPIO_CTL),
 214         REGISTER_AB(GLB_CTL),
 215         /* FATAL_INTR_KER and FATAL_INTR_CHAR are partly RC */
 216         REGISTER_BZ(DP_CTRL),
 217         REGISTER_AZ(MEM_STAT),
 218         REGISTER_AZ(CS_DEBUG),
 219         REGISTER_AZ(ALTERA_BUILD),
 220         REGISTER_AZ(CSR_SPARE),
 221         REGISTER_AB(PCIE_SD_CTL0123),
 222         REGISTER_AB(PCIE_SD_CTL45),
 223         REGISTER_AB(PCIE_PCS_CTL_STAT),
 224         /* DEBUG_DATA_OUT is not used */
 225         /* DRV_EV is WO */
 226         REGISTER_AZ(EVQ_CTL),
 227         REGISTER_AZ(EVQ_CNT1),
 228         REGISTER_AZ(EVQ_CNT2),
 229         REGISTER_AZ(BUF_TBL_CFG),
 230         REGISTER_AZ(SRM_RX_DC_CFG),
 231         REGISTER_AZ(SRM_TX_DC_CFG),
 232         REGISTER_AZ(SRM_CFG),
 233         /* BUF_TBL_UPD is WO */
 234         REGISTER_AZ(SRM_UPD_EVQ),
 235         REGISTER_AZ(SRAM_PARITY),
 236         REGISTER_AZ(RX_CFG),
 237         REGISTER_BZ(RX_FILTER_CTL),
 238         /* RX_FLUSH_DESCQ is WO */
 239         REGISTER_AZ(RX_DC_CFG),
 240         REGISTER_AZ(RX_DC_PF_WM),
 241         REGISTER_BZ(RX_RSS_TKEY),
 242         /* RX_NODESC_DROP is RC */
 243         REGISTER_AA(RX_SELF_RST),
 244         /* RX_DEBUG, RX_PUSH_DROP are not used */
 245         REGISTER_CZ(RX_RSS_IPV6_REG1),
 246         REGISTER_CZ(RX_RSS_IPV6_REG2),
 247         REGISTER_CZ(RX_RSS_IPV6_REG3),
 248         /* TX_FLUSH_DESCQ is WO */
 249         REGISTER_AZ(TX_DC_CFG),
 250         REGISTER_AA(TX_CHKSM_CFG),
 251         REGISTER_AZ(TX_CFG),
 252         /* TX_PUSH_DROP is not used */
 253         REGISTER_AZ(TX_RESERVED),
 254         REGISTER_BZ(TX_PACE),
 255         /* TX_PACE_DROP_QID is RC */
 256         REGISTER_BB(TX_VLAN),
 257         REGISTER_BZ(TX_IPFIL_PORTEN),
 258         REGISTER_AB(MD_TXD),
 259         REGISTER_AB(MD_RXD),
 260         REGISTER_AB(MD_CS),
 261         REGISTER_AB(MD_PHY_ADR),
 262         REGISTER_AB(MD_ID),
 263         /* MD_STAT is RC */
 264         REGISTER_AB(MAC_STAT_DMA),
 265         REGISTER_AB(MAC_CTRL),
 266         REGISTER_BB(GEN_MODE),
 267         REGISTER_AB(MAC_MC_HASH_REG0),
 268         REGISTER_AB(MAC_MC_HASH_REG1),
 269         REGISTER_AB(GM_CFG1),
 270         REGISTER_AB(GM_CFG2),
 271         /* GM_IPG and GM_HD are not used */
 272         REGISTER_AB(GM_MAX_FLEN),
 273         /* GM_TEST is not used */
 274         REGISTER_AB(GM_ADR1),
 275         REGISTER_AB(GM_ADR2),
 276         REGISTER_AB(GMF_CFG0),
 277         REGISTER_AB(GMF_CFG1),
 278         REGISTER_AB(GMF_CFG2),
 279         REGISTER_AB(GMF_CFG3),
 280         REGISTER_AB(GMF_CFG4),
 281         REGISTER_AB(GMF_CFG5),
 282         REGISTER_BB(TX_SRC_MAC_CTL),
 283         REGISTER_AB(XM_ADR_LO),
 284         REGISTER_AB(XM_ADR_HI),
 285         REGISTER_AB(XM_GLB_CFG),
 286         REGISTER_AB(XM_TX_CFG),
 287         REGISTER_AB(XM_RX_CFG),
 288         REGISTER_AB(XM_MGT_INT_MASK),
 289         REGISTER_AB(XM_FC),
 290         REGISTER_AB(XM_PAUSE_TIME),
 291         REGISTER_AB(XM_TX_PARAM),
 292         REGISTER_AB(XM_RX_PARAM),
 293         /* XM_MGT_INT_MSK (note no 'A') is RC */
 294         REGISTER_AB(XX_PWR_RST),
 295         REGISTER_AB(XX_SD_CTL),
 296         REGISTER_AB(XX_TXDRV_CTL),
 297         /* XX_PRBS_CTL, XX_PRBS_CHK and XX_PRBS_ERR are not used */
 298         /* XX_CORE_STAT is partly RC */
 299         REGISTER_DZ(BIU_HW_REV_ID),
 300         REGISTER_DZ(MC_DB_LWRD),
 301         REGISTER_DZ(MC_DB_HWRD),
 302 };
 303
 304 struct efx_nic_reg_table {
 305         u32 offset:24;
 306         u32 min_revision:3, max_revision:3;
 307         u32 step:6, rows:21;
 308 };
 309
 310 #define REGISTER_TABLE_DIMENSIONS(_, offset, arch, min_rev, max_rev, step, rows) { \
 311         offset,                                                         \
 312         REGISTER_REVISION_ ## arch ## min_rev,                          \
 313         REGISTER_REVISION_ ## arch ## max_rev,                          \
 314         step, rows                                                      \
 315 }
 316 #define REGISTER_TABLE(name, arch, min_rev, max_rev)                    \
 317         REGISTER_TABLE_DIMENSIONS(                                      \
 318                 name, arch ## R_ ## min_rev ## max_rev ## _ ## name,    \
 319                 arch, min_rev, max_rev,                                 \
 320                 arch ## R_ ## min_rev ## max_rev ## _ ## name ## _STEP, \
 321                 arch ## R_ ## min_rev ## max_rev ## _ ## name ## _ROWS)
 322 #define REGISTER_TABLE_AA(name) REGISTER_TABLE(name, F, A, A)
 323 #define REGISTER_TABLE_AZ(name) REGISTER_TABLE(name, F, A, Z)
 324 #define REGISTER_TABLE_BB(name) REGISTER_TABLE(name, F, B, B)
 325 #define REGISTER_TABLE_BZ(name) REGISTER_TABLE(name, F, B, Z)
 326 #define REGISTER_TABLE_BB_CZ(name)                                      \
 327         REGISTER_TABLE_DIMENSIONS(name, FR_BZ_ ## name, F, B, B,        \
 328                                   FR_BZ_ ## name ## _STEP,              \
 329                                   FR_BB_ ## name ## _ROWS),             \
 330         REGISTER_TABLE_DIMENSIONS(name, FR_BZ_ ## name, F, C, Z,        \
 331                                   FR_BZ_ ## name ## _STEP,              \
 332                                   FR_CZ_ ## name ## _ROWS)
 333 #define REGISTER_TABLE_CZ(name) REGISTER_TABLE(name, F, C, Z)
 334 #define REGISTER_TABLE_DZ(name) REGISTER_TABLE(name, E, D, 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         REGISTER_TABLE_DZ(BIU_MC_SFT_STATUS),
 366 };
 367
 368 size_t efx_nic_get_regs_len(struct efx_nic *efx)
 369 {
 370         const struct efx_nic_reg *reg;
 371         const struct efx_nic_reg_table *table;
 372         size_t len = 0;
 373
 374         for (reg = efx_nic_regs;
 375              reg < efx_nic_regs + ARRAY_SIZE(efx_nic_regs);
 376              reg++)
 377                 if (efx->type->revision >= reg->min_revision &&
 378                     efx->type->revision <= reg->max_revision)
 379                         len += sizeof(efx_oword_t);
 380
 381         for (table = efx_nic_reg_tables;
 382              table < efx_nic_reg_tables + ARRAY_SIZE(efx_nic_reg_tables);
 383              table++)
 384                 if (efx->type->revision >= table->min_revision &&
 385                     efx->type->revision <= table->max_revision)
 386                         len += table->rows * min_t(size_t, table->step, 16);
 387
 388         return len;
 389 }
 390
 391 void efx_nic_get_regs(struct efx_nic *efx, void *buf)
 392 {
 393         const struct efx_nic_reg *reg;
 394         const struct efx_nic_reg_table *table;
 395
 396         for (reg = efx_nic_regs;
 397              reg < efx_nic_regs + ARRAY_SIZE(efx_nic_regs);
 398              reg++) {
 399                 if (efx->type->revision >= reg->min_revision &&
 400                     efx->type->revision <= reg->max_revision) {
 401                         efx_reado(efx, (efx_oword_t *)buf, reg->offset);
 402                         buf += sizeof(efx_oword_t);
 403                 }
 404         }
 405
 406         for (table = efx_nic_reg_tables;
 407              table < efx_nic_reg_tables + ARRAY_SIZE(efx_nic_reg_tables);
 408              table++) {
 409                 size_t size, i;
 410
 411                 if (!(efx->type->revision >= table->min_revision &&
 412                       efx->type->revision <= table->max_revision))
 413                         continue;
 414
 415                 size = min_t(size_t, table->step, 16);
 416
 417                 for (i = 0; i < table->rows; i++) {
 418                         switch (table->step) {
 419                         case 4: /* 32-bit SRAM */
 420                                 efx_readd(efx, buf, table->offset + 4 * i);
 421                                 break;
 422                         case 8: /* 64-bit SRAM */
 423                                 efx_sram_readq(efx,
 424                                                efx->membase + table->offset,
 425                                                buf, i);
 426                                 break;
 427                         case 16: /* 128-bit-readable register */
 428                                 efx_reado_table(efx, buf, table->offset, i);
 429                                 break;
 430                         case 32: /* 128-bit register, interleaved */
 431                                 efx_reado_table(efx, buf, table->offset, 2 * i);
 432                                 break;
 433                         default:
 434                                 WARN_ON(1);
 435                                 return;
 436                         }
 437                         buf += size;
 438                 }
 439         }
 440 }
 441
 442 /**
 443  * efx_nic_describe_stats - Describe supported statistics for ethtool
 444  * @desc: Array of &struct efx_hw_stat_desc describing the statistics
 445  * @count: Length of the @desc array
 446  * @mask: Bitmask of which elements of @desc are enabled
 447  * @names: Buffer to copy names to, or %NULL.  The names are copied
 448  *      starting at intervals of %ETH_GSTRING_LEN bytes.
 449  *
 450  * Returns the number of visible statistics, i.e. the number of set
 451  * bits in the first @count bits of @mask for which a name is defined.
 452  */
 453 size_t efx_nic_describe_stats(const struct efx_hw_stat_desc *desc, size_t count,
 454                               const unsigned long *mask, u8 *names)
 455 {
 456         size_t visible = 0;
 457         size_t index;
 458
 459         for_each_set_bit(index, mask, count) {
 460                 if (desc[index].name) {
 461                         if (names) {
 462                                 strlcpy(names, desc[index].name,
 463                                         ETH_GSTRING_LEN);
 464                                 names += ETH_GSTRING_LEN;
 465                         }
 466                         ++visible;
 467                 }
 468         }
 469
 470         return visible;
 471 }
 472
 473 /**
 474  * efx_nic_update_stats - Convert statistics DMA buffer to array of u64
 475  * @desc: Array of &struct efx_hw_stat_desc describing the DMA buffer
 476  *      layout.  DMA widths of 0, 16, 32 and 64 are supported; where
 477  *      the width is specified as 0 the corresponding element of
 478  *      @stats is not updated.
 479  * @count: Length of the @desc array
 480  * @mask: Bitmask of which elements of @desc are enabled
 481  * @stats: Buffer to update with the converted statistics.  The length
 482  *      of this array must be at least @count.
 483  * @dma_buf: DMA buffer containing hardware statistics
 484  * @accumulate: If set, the converted values will be added rather than
 485  *      directly stored to the corresponding elements of @stats
 486  */
 487 void efx_nic_update_stats(const struct efx_hw_stat_desc *desc, size_t count,
 488                           const unsigned long *mask,
 489                           u64 *stats, const void *dma_buf, bool accumulate)
 490 {
 491         size_t index;
 492
 493         for_each_set_bit(index, mask, count) {
 494                 if (desc[index].dma_width) {
 495                         const void *addr = dma_buf + desc[index].offset;
 496                         u64 val;
 497
 498                         switch (desc[index].dma_width) {
 499                         case 16:
 500                                 val = le16_to_cpup((__le16 *)addr);
 501                                 break;
 502                         case 32:
 503                                 val = le32_to_cpup((__le32 *)addr);
 504                                 break;
 505                         case 64:
 506                                 val = le64_to_cpup((__le64 *)addr);
 507                                 break;
 508                         default:
 509                                 WARN_ON(1);
 510                                 val = 0;
 511                                 break;
 512                         }
 513
 514                         if (accumulate)
 515                                 stats[index] += val;
 516                         else
 517                                 stats[index] = val;
 518                 }
 519         }
 520 }
 521
 522 void efx_nic_fix_nodesc_drop_stat(struct efx_nic *efx, u64 *rx_nodesc_drops)
 523 {
 524         /* if down, or this is the first update after coming up */
 525         if (!(efx->net_dev->flags & IFF_UP) || !efx->rx_nodesc_drops_prev_state)
 526                 efx->rx_nodesc_drops_while_down +=
 527                         *rx_nodesc_drops - efx->rx_nodesc_drops_total;
 528         efx->rx_nodesc_drops_total = *rx_nodesc_drops;
 529         efx->rx_nodesc_drops_prev_state = !!(efx->net_dev->flags & IFF_UP);
 530         *rx_nodesc_drops -= efx->rx_nodesc_drops_while_down;
 531 }