kernel/drivers/net/ethernet/sfc/nic.c

   1 /****************************************************************************
   2  * Driver for Solarflare network controllers and boards
   3  * Copyright 2005-2006 Fen Systems Ltd.
   4  * Copyright 2006-2013 Solarflare Communications Inc.
   5  *
   6  * This program is free software; you can redistribute it and/or modify it
   7  * under the terms of the GNU General Public License version 2 as published
   8  * by the Free Software Foundation, incorporated herein by reference.
   9  */
  10
  11 #include <linux/bitops.h>
  12 #include <linux/delay.h>
  13 #include <linux/interrupt.h>
  14 #include <linux/pci.h>
  15 #include <linux/module.h>
  16 #include <linux/seq_file.h>
  17 #include <linux/cpu_rmap.h>
  18 #include "net_driver.h"
  19 #include "bitfield.h"
  20 #include "efx.h"
  21 #include "nic.h"
  22 #include "ef10_regs.h"
  23 #include "farch_regs.h"
  24 #include "io.h"
  25 #include "workarounds.h"
  26
  27 /**************************************************************************
  28  *
  29  * Generic buffer handling
  30  * These buffers are used for interrupt status, MAC stats, etc.
  31  *
  32  **************************************************************************/
  33
  34 int efx_nic_alloc_buffer(struct efx_nic *efx, struct efx_buffer *buffer,
  35                          unsigned int len, gfp_t gfp_flags)
  36 {
  37         buffer->addr = dma_zalloc_coherent(&efx->pci_dev->dev, len,
  38                                            &buffer->dma_addr, gfp_flags);
  39         if (!buffer->addr)
  40                 return -ENOMEM;
  41         buffer->len = len;
  42         return 0;
  43 }
  44
  45 void efx_nic_free_buffer(struct efx_nic *efx, struct efx_buffer *buffer)
  46 {
  47         if (buffer->addr) {
  48                 dma_free_coherent(&efx->pci_dev->dev, buffer->len,
  49                                   buffer->addr, buffer->dma_addr);
  50                 buffer->addr = NULL;
  51         }
  52 }
  53
  54 /* Check whether an event is present in the eventq at the current
  55  * read pointer.  Only useful for self-test.
  56  */
  57 bool efx_nic_event_present(struct efx_channel *channel)
  58 {
  59         return efx_event_present(efx_event(channel, channel->eventq_read_ptr));
  60 }
  61
  62 void efx_nic_event_test_start(struct efx_channel *channel)
  63 {
  64         channel->event_test_cpu = -1;
  65         smp_wmb();
  66         channel->efx->type->ev_test_generate(channel);
  67 }
  68
  69 void efx_nic_irq_test_start(struct efx_nic *efx)
  70 {
  71         efx->last_irq_cpu = -1;
  72         smp_wmb();
  73         efx->type->irq_test_generate(efx);
  74 }
  75
  76 /* Hook interrupt handler(s)
  77  * Try MSI and then legacy interrupts.
  78  */
  79 int efx_nic_init_interrupt(struct efx_nic *efx)
  80 {
  81         struct efx_channel *channel;
  82         unsigned int n_irqs;
  83         int rc;
  84
  85         if (!EFX_INT_MODE_USE_MSI(efx)) {
  86                 rc = request_irq(efx->legacy_irq,
  87                                  efx->type->irq_handle_legacy, IRQF_SHARED,
  88                                  efx->name, efx);
  89                 if (rc) {
  90                         netif_err(efx, drv, efx->net_dev,
  91                                   "failed to hook legacy IRQ %d\n",
  92                                   efx->pci_dev->irq);
  93                         goto fail1;
  94                 }
  95                 return 0;
  96         }
  97
  98 #ifdef CONFIG_RFS_ACCEL
  99         if (efx->interrupt_mode == EFX_INT_MODE_MSIX) {
 100                 efx->net_dev->rx_cpu_rmap =
 101                         alloc_irq_cpu_rmap(efx->n_rx_channels);
 102                 if (!efx->net_dev->rx_cpu_rmap) {
 103                         rc = -ENOMEM;
 104                         goto fail1;
 105                 }
 106         }
 107 #endif
 108
 109         /* Hook MSI or MSI-X interrupt */
 110         n_irqs = 0;
 111         efx_for_each_channel(channel, efx) {
 112                 rc = request_irq(channel->irq, efx->type->irq_handle_msi,
 113                                  IRQF_PROBE_SHARED, /* Not shared */
 114                                  efx->msi_context[channel->channel].name,
 115                                  &efx->msi_context[channel->channel]);
 116                 if (rc) {
 117                         netif_err(efx, drv, efx->net_dev,
 118                                   "failed to hook IRQ %d\n", channel->irq);
 119                         goto fail2;
 120                 }
 121                 ++n_irqs;
 122
 123 #ifdef CONFIG_RFS_ACCEL
 124                 if (efx->interrupt_mode == EFX_INT_MODE_MSIX &&
 125                     channel->channel < efx->n_rx_channels) {
 126                         rc = irq_cpu_rmap_add(efx->net_dev->rx_cpu_rmap,
 127                                               channel->irq);
 128                         if (rc)
 129                                 goto fail2;
 130                 }
 131 #endif
 132         }
 133
 134         return 0;
 135
 136  fail2:
 137 #ifdef CONFIG_RFS_ACCEL
 138         free_irq_cpu_rmap(efx->net_dev->rx_cpu_rmap);
 139         efx->net_dev->rx_cpu_rmap = NULL;
 140 #endif
 141         efx_for_each_channel(channel, efx) {
 142                 if (n_irqs-- == 0)
 143                         break;
 144                 free_irq(channel->irq, &efx->msi_context[channel->channel]);
 145         }
 146  fail1:
 147         return rc;
 148 }
 149
 150 void efx_nic_fini_interrupt(struct efx_nic *efx)
 151 {
 152         struct efx_channel *channel;
 153
 154 #ifdef CONFIG_RFS_ACCEL
 155         free_irq_cpu_rmap(efx->net_dev->rx_cpu_rmap);
 156         efx->net_dev->rx_cpu_rmap = NULL;
 157 #endif
 158
 159         if (EFX_INT_MODE_USE_MSI(efx)) {
 160                 /* Disable MSI/MSI-X interrupts */
 161                 efx_for_each_channel(channel, efx)
 162                         free_irq(channel->irq,
 163                                  &efx->msi_context[channel->channel]);
 164         } else {
 165                 /* Disable legacy interrupt */
 166                 free_irq(efx->legacy_irq, efx);
 167         }
 168 }
 169
 170 /* Register dump */
 171
 172 #define REGISTER_REVISION_FA    1
 173 #define REGISTER_REVISION_FB    2
 174 #define REGISTER_REVISION_FC    3
 175 #define REGISTER_REVISION_FZ    3       /* last Falcon arch revision */
 176 #define REGISTER_REVISION_ED    4
 177 #define REGISTER_REVISION_EZ    4       /* latest EF10 revision */
 178
 179 struct efx_nic_reg {
 180         u32 offset:24;
 181         u32 min_revision:3, max_revision:3;
 182 };
 183
 184 #define REGISTER(name, arch, min_rev, max_rev) {                        \
 185         arch ## R_ ## min_rev ## max_rev ## _ ## name,                  \
 186         REGISTER_REVISION_ ## arch ## min_rev,                          \
 187         REGISTER_REVISION_ ## arch ## max_rev                           \
 188 }
 189 #define REGISTER_AA(name) REGISTER(name, F, A, A)
 190 #define REGISTER_AB(name) REGISTER(name, F, A, B)
 191 #define REGISTER_AZ(name) REGISTER(name, F, A, Z)
 192 #define REGISTER_BB(name) REGISTER(name, F, B, B)
 193 #define REGISTER_BZ(name) REGISTER(name, F, B, Z)
 194 #define REGISTER_CZ(name) REGISTER(name, F, C, Z)
 195 #define REGISTER_DZ(name) REGISTER(name, E, D, Z)
 196
 197 static const struct efx_nic_reg efx_nic_regs[] = {
 198         REGISTER_AZ(ADR_REGION),
 199         REGISTER_AZ(INT_EN_KER),
 200         REGISTER_BZ(INT_EN_CHAR),
 201         REGISTER_AZ(INT_ADR_KER),
 202         REGISTER_BZ(INT_ADR_CHAR),
 203         /* INT_ACK_KER is WO */
 204         /* INT_ISR0 is RC */
 205         REGISTER_AZ(HW_INIT),
 206         REGISTER_CZ(USR_EV_CFG),
 207         REGISTER_AB(EE_SPI_HCMD),
 208         REGISTER_AB(EE_SPI_HADR),
 209         REGISTER_AB(EE_SPI_HDATA),
 210         REGISTER_AB(EE_BASE_PAGE),
 211         REGISTER_AB(EE_VPD_CFG0),
 212         /* EE_VPD_SW_CNTL and EE_VPD_SW_DATA are not used */
 213         /* PMBX_DBG_IADDR and PBMX_DBG_IDATA are indirect */
 214         /* PCIE_CORE_INDIRECT is indirect */
 215         REGISTER_AB(NIC_STAT),
 216         REGISTER_AB(GPIO_CTL),
 217         REGISTER_AB(GLB_CTL),
 218         /* FATAL_INTR_KER and FATAL_INTR_CHAR are partly RC */
 219         REGISTER_BZ(DP_CTRL),
 220         REGISTER_AZ(MEM_STAT),
 221         REGISTER_AZ(CS_DEBUG),
 222         REGISTER_AZ(ALTERA_BUILD),
 223         REGISTER_AZ(CSR_SPARE),
 224         REGISTER_AB(PCIE_SD_CTL0123),
 225         REGISTER_AB(PCIE_SD_CTL45),
 226         REGISTER_AB(PCIE_PCS_CTL_STAT),
 227         /* DEBUG_DATA_OUT is not used */
 228         /* DRV_EV is WO */
 229         REGISTER_AZ(EVQ_CTL),
 230         REGISTER_AZ(EVQ_CNT1),
 231         REGISTER_AZ(EVQ_CNT2),
 232         REGISTER_AZ(BUF_TBL_CFG),
 233         REGISTER_AZ(SRM_RX_DC_CFG),
 234         REGISTER_AZ(SRM_TX_DC_CFG),
 235         REGISTER_AZ(SRM_CFG),
 236         /* BUF_TBL_UPD is WO */
 237         REGISTER_AZ(SRM_UPD_EVQ),
 238         REGISTER_AZ(SRAM_PARITY),
 239         REGISTER_AZ(RX_CFG),
 240         REGISTER_BZ(RX_FILTER_CTL),
 241         /* RX_FLUSH_DESCQ is WO */
 242         REGISTER_AZ(RX_DC_CFG),
 243         REGISTER_AZ(RX_DC_PF_WM),
 244         REGISTER_BZ(RX_RSS_TKEY),
 245         /* RX_NODESC_DROP is RC */
 246         REGISTER_AA(RX_SELF_RST),
 247         /* RX_DEBUG, RX_PUSH_DROP are not used */
 248         REGISTER_CZ(RX_RSS_IPV6_REG1),
 249         REGISTER_CZ(RX_RSS_IPV6_REG2),
 250         REGISTER_CZ(RX_RSS_IPV6_REG3),
 251         /* TX_FLUSH_DESCQ is WO */
 252         REGISTER_AZ(TX_DC_CFG),
 253         REGISTER_AA(TX_CHKSM_CFG),
 254         REGISTER_AZ(TX_CFG),
 255         /* TX_PUSH_DROP is not used */
 256         REGISTER_AZ(TX_RESERVED),
 257         REGISTER_BZ(TX_PACE),
 258         /* TX_PACE_DROP_QID is RC */
 259         REGISTER_BB(TX_VLAN),
 260         REGISTER_BZ(TX_IPFIL_PORTEN),
 261         REGISTER_AB(MD_TXD),
 262         REGISTER_AB(MD_RXD),
 263         REGISTER_AB(MD_CS),
 264         REGISTER_AB(MD_PHY_ADR),
 265         REGISTER_AB(MD_ID),
 266         /* MD_STAT is RC */
 267         REGISTER_AB(MAC_STAT_DMA),
 268         REGISTER_AB(MAC_CTRL),
 269         REGISTER_BB(GEN_MODE),
 270         REGISTER_AB(MAC_MC_HASH_REG0),
 271         REGISTER_AB(MAC_MC_HASH_REG1),
 272         REGISTER_AB(GM_CFG1),
 273         REGISTER_AB(GM_CFG2),
 274         /* GM_IPG and GM_HD are not used */
 275         REGISTER_AB(GM_MAX_FLEN),
 276         /* GM_TEST is not used */
 277         REGISTER_AB(GM_ADR1),
 278         REGISTER_AB(GM_ADR2),
 279         REGISTER_AB(GMF_CFG0),
 280         REGISTER_AB(GMF_CFG1),
 281         REGISTER_AB(GMF_CFG2),
 282         REGISTER_AB(GMF_CFG3),
 283         REGISTER_AB(GMF_CFG4),
 284         REGISTER_AB(GMF_CFG5),
 285         REGISTER_BB(TX_SRC_MAC_CTL),
 286         REGISTER_AB(XM_ADR_LO),
 287         REGISTER_AB(XM_ADR_HI),
 288         REGISTER_AB(XM_GLB_CFG),
 289         REGISTER_AB(XM_TX_CFG),
 290         REGISTER_AB(XM_RX_CFG),
 291         REGISTER_AB(XM_MGT_INT_MASK),
 292         REGISTER_AB(XM_FC),
 293         REGISTER_AB(XM_PAUSE_TIME),
 294         REGISTER_AB(XM_TX_PARAM),
 295         REGISTER_AB(XM_RX_PARAM),
 296         /* XM_MGT_INT_MSK (note no 'A') is RC */
 297         REGISTER_AB(XX_PWR_RST),
 298         REGISTER_AB(XX_SD_CTL),
 299         REGISTER_AB(XX_TXDRV_CTL),
 300         /* XX_PRBS_CTL, XX_PRBS_CHK and XX_PRBS_ERR are not used */
 301         /* XX_CORE_STAT is partly RC */
 302         REGISTER_DZ(BIU_HW_REV_ID),
 303         REGISTER_DZ(MC_DB_LWRD),
 304         REGISTER_DZ(MC_DB_HWRD),
 305 };
 306
 307 struct efx_nic_reg_table {
 308         u32 offset:24;
 309         u32 min_revision:3, max_revision:3;
 310         u32 step:6, rows:21;
 311 };
 312
 313 #define REGISTER_TABLE_DIMENSIONS(_, offset, arch, min_rev, max_rev, step, rows) { \
 314         offset,                                                         \
 315         REGISTER_REVISION_ ## arch ## min_rev,                          \
 316         REGISTER_REVISION_ ## arch ## max_rev,                          \
 317         step, rows                                                      \
 318 }
 319 #define REGISTER_TABLE(name, arch, min_rev, max_rev)                    \
 320         REGISTER_TABLE_DIMENSIONS(                                      \
 321                 name, arch ## R_ ## min_rev ## max_rev ## _ ## name,    \
 322                 arch, min_rev, max_rev,                                 \
 323                 arch ## R_ ## min_rev ## max_rev ## _ ## name ## _STEP, \
 324                 arch ## R_ ## min_rev ## max_rev ## _ ## name ## _ROWS)
 325 #define REGISTER_TABLE_AA(name) REGISTER_TABLE(name, F, A, A)
 326 #define REGISTER_TABLE_AZ(name) REGISTER_TABLE(name, F, A, Z)
 327 #define REGISTER_TABLE_BB(name) REGISTER_TABLE(name, F, B, B)
 328 #define REGISTER_TABLE_BZ(name) REGISTER_TABLE(name, F, B, Z)
 329 #define REGISTER_TABLE_BB_CZ(name)                                      \
 330         REGISTER_TABLE_DIMENSIONS(name, FR_BZ_ ## name, F, B, B,        \
 331                                   FR_BZ_ ## name ## _STEP,              \
 332                                   FR_BB_ ## name ## _ROWS),             \
 333         REGISTER_TABLE_DIMENSIONS(name, FR_BZ_ ## name, F, C, Z,        \
 334                                   FR_BZ_ ## name ## _STEP,              \
 335                                   FR_CZ_ ## name ## _ROWS)
 336 #define REGISTER_TABLE_CZ(name) REGISTER_TABLE(name, F, C, Z)
 337 #define REGISTER_TABLE_DZ(name) REGISTER_TABLE(name, E, D, Z)
 338
 339 static const struct efx_nic_reg_table efx_nic_reg_tables[] = {
 340         /* DRIVER is not used */
 341         /* EVQ_RPTR, TIMER_COMMAND, USR_EV and {RX,TX}_DESC_UPD are WO */
 342         REGISTER_TABLE_BB(TX_IPFIL_TBL),
 343         REGISTER_TABLE_BB(TX_SRC_MAC_TBL),
 344         REGISTER_TABLE_AA(RX_DESC_PTR_TBL_KER),
 345         REGISTER_TABLE_BB_CZ(RX_DESC_PTR_TBL),
 346         REGISTER_TABLE_AA(TX_DESC_PTR_TBL_KER),
 347         REGISTER_TABLE_BB_CZ(TX_DESC_PTR_TBL),
 348         REGISTER_TABLE_AA(EVQ_PTR_TBL_KER),
 349         REGISTER_TABLE_BB_CZ(EVQ_PTR_TBL),
 350         /* We can't reasonably read all of the buffer table (up to 8MB!).
 351          * However this driver will only use a few entries.  Reading
 352          * 1K entries allows for some expansion of queue count and
 353          * size before we need to change the version. */
 354         REGISTER_TABLE_DIMENSIONS(BUF_FULL_TBL_KER, FR_AA_BUF_FULL_TBL_KER,
 355                                   F, A, A, 8, 1024),
 356         REGISTER_TABLE_DIMENSIONS(BUF_FULL_TBL, FR_BZ_BUF_FULL_TBL,
 357                                   F, B, Z, 8, 1024),
 358         REGISTER_TABLE_CZ(RX_MAC_FILTER_TBL0),
 359         REGISTER_TABLE_BB_CZ(TIMER_TBL),
 360         REGISTER_TABLE_BB_CZ(TX_PACE_TBL),
 361         REGISTER_TABLE_BZ(RX_INDIRECTION_TBL),
 362         /* TX_FILTER_TBL0 is huge and not used by this driver */
 363         REGISTER_TABLE_CZ(TX_MAC_FILTER_TBL0),
 364         REGISTER_TABLE_CZ(MC_TREG_SMEM),
 365         /* MSIX_PBA_TABLE is not mapped */
 366         /* SRM_DBG is not mapped (and is redundant with BUF_FLL_TBL) */
 367         REGISTER_TABLE_BZ(RX_FILTER_TBL0),
 368         REGISTER_TABLE_DZ(BIU_MC_SFT_STATUS),
 369 };
 370
 371 size_t efx_nic_get_regs_len(struct efx_nic *efx)
 372 {
 373         const struct efx_nic_reg *reg;
 374         const struct efx_nic_reg_table *table;
 375         size_t len = 0;
 376
 377         for (reg = efx_nic_regs;
 378              reg < efx_nic_regs + ARRAY_SIZE(efx_nic_regs);
 379              reg++)
 380                 if (efx->type->revision >= reg->min_revision &&
 381                     efx->type->revision <= reg->max_revision)
 382                         len += sizeof(efx_oword_t);
 383
 384         for (table = efx_nic_reg_tables;
 385              table < efx_nic_reg_tables + ARRAY_SIZE(efx_nic_reg_tables);
 386              table++)
 387                 if (efx->type->revision >= table->min_revision &&
 388                     efx->type->revision <= table->max_revision)
 389                         len += table->rows * min_t(size_t, table->step, 16);
 390
 391         return len;
 392 }
 393
 394 void efx_nic_get_regs(struct efx_nic *efx, void *buf)
 395 {
 396         const struct efx_nic_reg *reg;
 397         const struct efx_nic_reg_table *table;
 398
 399         for (reg = efx_nic_regs;
 400              reg < efx_nic_regs + ARRAY_SIZE(efx_nic_regs);
 401              reg++) {
 402                 if (efx->type->revision >= reg->min_revision &&
 403                     efx->type->revision <= reg->max_revision) {
 404                         efx_reado(efx, (efx_oword_t *)buf, reg->offset);
 405                         buf += sizeof(efx_oword_t);
 406                 }
 407         }
 408
 409         for (table = efx_nic_reg_tables;
 410              table < efx_nic_reg_tables + ARRAY_SIZE(efx_nic_reg_tables);
 411              table++) {
 412                 size_t size, i;
 413
 414                 if (!(efx->type->revision >= table->min_revision &&
 415                       efx->type->revision <= table->max_revision))
 416                         continue;
 417
 418                 size = min_t(size_t, table->step, 16);
 419
 420                 for (i = 0; i < table->rows; i++) {
 421                         switch (table->step) {
 422                         case 4: /* 32-bit SRAM */
 423                                 efx_readd(efx, buf, table->offset + 4 * i);
 424                                 break;
 425                         case 8: /* 64-bit SRAM */
 426                                 efx_sram_readq(efx,
 427                                                efx->membase + table->offset,
 428                                                buf, i);
 429                                 break;
 430                         case 16: /* 128-bit-readable register */
 431                                 efx_reado_table(efx, buf, table->offset, i);
 432                                 break;
 433                         case 32: /* 128-bit register, interleaved */
 434                                 efx_reado_table(efx, buf, table->offset, 2 * i);
 435                                 break;
 436                         default:
 437                                 WARN_ON(1);
 438                                 return;
 439                         }
 440                         buf += size;
 441                 }
 442         }
 443 }
 444
 445 /**
 446  * efx_nic_describe_stats - Describe supported statistics for ethtool
 447  * @desc: Array of &struct efx_hw_stat_desc describing the statistics
 448  * @count: Length of the @desc array
 449  * @mask: Bitmask of which elements of @desc are enabled
 450  * @names: Buffer to copy names to, or %NULL.  The names are copied
 451  *      starting at intervals of %ETH_GSTRING_LEN bytes.
 452  *
 453  * Returns the number of visible statistics, i.e. the number of set
 454  * bits in the first @count bits of @mask for which a name is defined.
 455  */
 456 size_t efx_nic_describe_stats(const struct efx_hw_stat_desc *desc, size_t count,
 457                               const unsigned long *mask, u8 *names)
 458 {
 459         size_t visible = 0;
 460         size_t index;
 461
 462         for_each_set_bit(index, mask, count) {
 463                 if (desc[index].name) {
 464                         if (names) {
 465                                 strlcpy(names, desc[index].name,
 466                                         ETH_GSTRING_LEN);
 467                                 names += ETH_GSTRING_LEN;
 468                         }
 469                         ++visible;
 470                 }
 471         }
 472
 473         return visible;
 474 }
 475
 476 /**
 477  * efx_nic_update_stats - Convert statistics DMA buffer to array of u64
 478  * @desc: Array of &struct efx_hw_stat_desc describing the DMA buffer
 479  *      layout.  DMA widths of 0, 16, 32 and 64 are supported; where
 480  *      the width is specified as 0 the corresponding element of
 481  *      @stats is not updated.
 482  * @count: Length of the @desc array
 483  * @mask: Bitmask of which elements of @desc are enabled
 484  * @stats: Buffer to update with the converted statistics.  The length
 485  *      of this array must be at least @count.
 486  * @dma_buf: DMA buffer containing hardware statistics
 487  * @accumulate: If set, the converted values will be added rather than
 488  *      directly stored to the corresponding elements of @stats
 489  */
 490 void efx_nic_update_stats(const struct efx_hw_stat_desc *desc, size_t count,
 491                           const unsigned long *mask,
 492                           u64 *stats, const void *dma_buf, bool accumulate)
 493 {
 494         size_t index;
 495
 496         for_each_set_bit(index, mask, count) {
 497                 if (desc[index].dma_width) {
 498                         const void *addr = dma_buf + desc[index].offset;
 499                         u64 val;
 500
 501                         switch (desc[index].dma_width) {
 502                         case 16:
 503                                 val = le16_to_cpup((__le16 *)addr);
 504                                 break;
 505                         case 32:
 506                                 val = le32_to_cpup((__le32 *)addr);
 507                                 break;
 508                         case 64:
 509                                 val = le64_to_cpup((__le64 *)addr);
 510                                 break;
 511                         default:
 512                                 WARN_ON(1);
 513                                 val = 0;
 514                                 break;
 515                         }
 516
 517                         if (accumulate)
 518                                 stats[index] += val;
 519                         else
 520                                 stats[index] = val;
 521                 }
 522         }
 523 }
 524
 525 void efx_nic_fix_nodesc_drop_stat(struct efx_nic *efx, u64 *rx_nodesc_drops)
 526 {
 527         /* if down, or this is the first update after coming up */
 528         if (!(efx->net_dev->flags & IFF_UP) || !efx->rx_nodesc_drops_prev_state)
 529                 efx->rx_nodesc_drops_while_down +=
 530                         *rx_nodesc_drops - efx->rx_nodesc_drops_total;
 531         efx->rx_nodesc_drops_total = *rx_nodesc_drops;
 532         efx->rx_nodesc_drops_prev_state = !!(efx->net_dev->flags & IFF_UP);
 533         *rx_nodesc_drops -= efx->rx_nodesc_drops_while_down;
 534 }