cachepc-linux

Fork of AMDESE/linux with modifications for CachePC side-channel attack
git clone https://git.sinitax.com/sinitax/cachepc-linux
Log | Files | Refs | README | LICENSE | sfeed.txt

igc_i225.c (16582B)


      1// SPDX-License-Identifier: GPL-2.0
      2/* Copyright (c)  2018 Intel Corporation */
      3
      4#include <linux/delay.h>
      5
      6#include "igc_hw.h"
      7
      8/**
      9 * igc_acquire_nvm_i225 - Acquire exclusive access to EEPROM
     10 * @hw: pointer to the HW structure
     11 *
     12 * Acquire the necessary semaphores for exclusive access to the EEPROM.
     13 * Set the EEPROM access request bit and wait for EEPROM access grant bit.
     14 * Return successful if access grant bit set, else clear the request for
     15 * EEPROM access and return -IGC_ERR_NVM (-1).
     16 */
     17static s32 igc_acquire_nvm_i225(struct igc_hw *hw)
     18{
     19	return igc_acquire_swfw_sync_i225(hw, IGC_SWFW_EEP_SM);
     20}
     21
     22/**
     23 * igc_release_nvm_i225 - Release exclusive access to EEPROM
     24 * @hw: pointer to the HW structure
     25 *
     26 * Stop any current commands to the EEPROM and clear the EEPROM request bit,
     27 * then release the semaphores acquired.
     28 */
     29static void igc_release_nvm_i225(struct igc_hw *hw)
     30{
     31	igc_release_swfw_sync_i225(hw, IGC_SWFW_EEP_SM);
     32}
     33
     34/**
     35 * igc_get_hw_semaphore_i225 - Acquire hardware semaphore
     36 * @hw: pointer to the HW structure
     37 *
     38 * Acquire the HW semaphore to access the PHY or NVM
     39 */
     40static s32 igc_get_hw_semaphore_i225(struct igc_hw *hw)
     41{
     42	s32 timeout = hw->nvm.word_size + 1;
     43	s32 i = 0;
     44	u32 swsm;
     45
     46	/* Get the SW semaphore */
     47	while (i < timeout) {
     48		swsm = rd32(IGC_SWSM);
     49		if (!(swsm & IGC_SWSM_SMBI))
     50			break;
     51
     52		usleep_range(500, 600);
     53		i++;
     54	}
     55
     56	if (i == timeout) {
     57		/* In rare circumstances, the SW semaphore may already be held
     58		 * unintentionally. Clear the semaphore once before giving up.
     59		 */
     60		if (hw->dev_spec._base.clear_semaphore_once) {
     61			hw->dev_spec._base.clear_semaphore_once = false;
     62			igc_put_hw_semaphore(hw);
     63			for (i = 0; i < timeout; i++) {
     64				swsm = rd32(IGC_SWSM);
     65				if (!(swsm & IGC_SWSM_SMBI))
     66					break;
     67
     68				usleep_range(500, 600);
     69			}
     70		}
     71
     72		/* If we do not have the semaphore here, we have to give up. */
     73		if (i == timeout) {
     74			hw_dbg("Driver can't access device - SMBI bit is set.\n");
     75			return -IGC_ERR_NVM;
     76		}
     77	}
     78
     79	/* Get the FW semaphore. */
     80	for (i = 0; i < timeout; i++) {
     81		swsm = rd32(IGC_SWSM);
     82		wr32(IGC_SWSM, swsm | IGC_SWSM_SWESMBI);
     83
     84		/* Semaphore acquired if bit latched */
     85		if (rd32(IGC_SWSM) & IGC_SWSM_SWESMBI)
     86			break;
     87
     88		usleep_range(500, 600);
     89	}
     90
     91	if (i == timeout) {
     92		/* Release semaphores */
     93		igc_put_hw_semaphore(hw);
     94		hw_dbg("Driver can't access the NVM\n");
     95		return -IGC_ERR_NVM;
     96	}
     97
     98	return 0;
     99}
    100
    101/**
    102 * igc_acquire_swfw_sync_i225 - Acquire SW/FW semaphore
    103 * @hw: pointer to the HW structure
    104 * @mask: specifies which semaphore to acquire
    105 *
    106 * Acquire the SW/FW semaphore to access the PHY or NVM.  The mask
    107 * will also specify which port we're acquiring the lock for.
    108 */
    109s32 igc_acquire_swfw_sync_i225(struct igc_hw *hw, u16 mask)
    110{
    111	s32 i = 0, timeout = 200;
    112	u32 fwmask = mask << 16;
    113	u32 swmask = mask;
    114	s32 ret_val = 0;
    115	u32 swfw_sync;
    116
    117	while (i < timeout) {
    118		if (igc_get_hw_semaphore_i225(hw)) {
    119			ret_val = -IGC_ERR_SWFW_SYNC;
    120			goto out;
    121		}
    122
    123		swfw_sync = rd32(IGC_SW_FW_SYNC);
    124		if (!(swfw_sync & (fwmask | swmask)))
    125			break;
    126
    127		/* Firmware currently using resource (fwmask) */
    128		igc_put_hw_semaphore(hw);
    129		mdelay(5);
    130		i++;
    131	}
    132
    133	if (i == timeout) {
    134		hw_dbg("Driver can't access resource, SW_FW_SYNC timeout.\n");
    135		ret_val = -IGC_ERR_SWFW_SYNC;
    136		goto out;
    137	}
    138
    139	swfw_sync |= swmask;
    140	wr32(IGC_SW_FW_SYNC, swfw_sync);
    141
    142	igc_put_hw_semaphore(hw);
    143out:
    144	return ret_val;
    145}
    146
    147/**
    148 * igc_release_swfw_sync_i225 - Release SW/FW semaphore
    149 * @hw: pointer to the HW structure
    150 * @mask: specifies which semaphore to acquire
    151 *
    152 * Release the SW/FW semaphore used to access the PHY or NVM.  The mask
    153 * will also specify which port we're releasing the lock for.
    154 */
    155void igc_release_swfw_sync_i225(struct igc_hw *hw, u16 mask)
    156{
    157	u32 swfw_sync;
    158
    159	/* Releasing the resource requires first getting the HW semaphore.
    160	 * If we fail to get the semaphore, there is nothing we can do,
    161	 * except log an error and quit. We are not allowed to hang here
    162	 * indefinitely, as it may cause denial of service or system crash.
    163	 */
    164	if (igc_get_hw_semaphore_i225(hw)) {
    165		hw_dbg("Failed to release SW_FW_SYNC.\n");
    166		return;
    167	}
    168
    169	swfw_sync = rd32(IGC_SW_FW_SYNC);
    170	swfw_sync &= ~mask;
    171	wr32(IGC_SW_FW_SYNC, swfw_sync);
    172
    173	igc_put_hw_semaphore(hw);
    174}
    175
    176/**
    177 * igc_read_nvm_srrd_i225 - Reads Shadow Ram using EERD register
    178 * @hw: pointer to the HW structure
    179 * @offset: offset of word in the Shadow Ram to read
    180 * @words: number of words to read
    181 * @data: word read from the Shadow Ram
    182 *
    183 * Reads a 16 bit word from the Shadow Ram using the EERD register.
    184 * Uses necessary synchronization semaphores.
    185 */
    186static s32 igc_read_nvm_srrd_i225(struct igc_hw *hw, u16 offset, u16 words,
    187				  u16 *data)
    188{
    189	s32 status = 0;
    190	u16 i, count;
    191
    192	/* We cannot hold synchronization semaphores for too long,
    193	 * because of forceful takeover procedure. However it is more efficient
    194	 * to read in bursts than synchronizing access for each word.
    195	 */
    196	for (i = 0; i < words; i += IGC_EERD_EEWR_MAX_COUNT) {
    197		count = (words - i) / IGC_EERD_EEWR_MAX_COUNT > 0 ?
    198			IGC_EERD_EEWR_MAX_COUNT : (words - i);
    199
    200		status = hw->nvm.ops.acquire(hw);
    201		if (status)
    202			break;
    203
    204		status = igc_read_nvm_eerd(hw, offset, count, data + i);
    205		hw->nvm.ops.release(hw);
    206		if (status)
    207			break;
    208	}
    209
    210	return status;
    211}
    212
    213/**
    214 * igc_write_nvm_srwr - Write to Shadow Ram using EEWR
    215 * @hw: pointer to the HW structure
    216 * @offset: offset within the Shadow Ram to be written to
    217 * @words: number of words to write
    218 * @data: 16 bit word(s) to be written to the Shadow Ram
    219 *
    220 * Writes data to Shadow Ram at offset using EEWR register.
    221 *
    222 * If igc_update_nvm_checksum is not called after this function , the
    223 * Shadow Ram will most likely contain an invalid checksum.
    224 */
    225static s32 igc_write_nvm_srwr(struct igc_hw *hw, u16 offset, u16 words,
    226			      u16 *data)
    227{
    228	struct igc_nvm_info *nvm = &hw->nvm;
    229	s32 ret_val = -IGC_ERR_NVM;
    230	u32 attempts = 100000;
    231	u32 i, k, eewr = 0;
    232
    233	/* A check for invalid values:  offset too large, too many words,
    234	 * too many words for the offset, and not enough words.
    235	 */
    236	if (offset >= nvm->word_size || (words > (nvm->word_size - offset)) ||
    237	    words == 0) {
    238		hw_dbg("nvm parameter(s) out of bounds\n");
    239		return ret_val;
    240	}
    241
    242	for (i = 0; i < words; i++) {
    243		ret_val = -IGC_ERR_NVM;
    244		eewr = ((offset + i) << IGC_NVM_RW_ADDR_SHIFT) |
    245			(data[i] << IGC_NVM_RW_REG_DATA) |
    246			IGC_NVM_RW_REG_START;
    247
    248		wr32(IGC_SRWR, eewr);
    249
    250		for (k = 0; k < attempts; k++) {
    251			if (IGC_NVM_RW_REG_DONE &
    252			    rd32(IGC_SRWR)) {
    253				ret_val = 0;
    254				break;
    255			}
    256			udelay(5);
    257		}
    258
    259		if (ret_val) {
    260			hw_dbg("Shadow RAM write EEWR timed out\n");
    261			break;
    262		}
    263	}
    264
    265	return ret_val;
    266}
    267
    268/**
    269 * igc_write_nvm_srwr_i225 - Write to Shadow RAM using EEWR
    270 * @hw: pointer to the HW structure
    271 * @offset: offset within the Shadow RAM to be written to
    272 * @words: number of words to write
    273 * @data: 16 bit word(s) to be written to the Shadow RAM
    274 *
    275 * Writes data to Shadow RAM at offset using EEWR register.
    276 *
    277 * If igc_update_nvm_checksum is not called after this function , the
    278 * data will not be committed to FLASH and also Shadow RAM will most likely
    279 * contain an invalid checksum.
    280 *
    281 * If error code is returned, data and Shadow RAM may be inconsistent - buffer
    282 * partially written.
    283 */
    284static s32 igc_write_nvm_srwr_i225(struct igc_hw *hw, u16 offset, u16 words,
    285				   u16 *data)
    286{
    287	s32 status = 0;
    288	u16 i, count;
    289
    290	/* We cannot hold synchronization semaphores for too long,
    291	 * because of forceful takeover procedure. However it is more efficient
    292	 * to write in bursts than synchronizing access for each word.
    293	 */
    294	for (i = 0; i < words; i += IGC_EERD_EEWR_MAX_COUNT) {
    295		count = (words - i) / IGC_EERD_EEWR_MAX_COUNT > 0 ?
    296			IGC_EERD_EEWR_MAX_COUNT : (words - i);
    297
    298		status = hw->nvm.ops.acquire(hw);
    299		if (status)
    300			break;
    301
    302		status = igc_write_nvm_srwr(hw, offset, count, data + i);
    303		hw->nvm.ops.release(hw);
    304		if (status)
    305			break;
    306	}
    307
    308	return status;
    309}
    310
    311/**
    312 * igc_validate_nvm_checksum_i225 - Validate EEPROM checksum
    313 * @hw: pointer to the HW structure
    314 *
    315 * Calculates the EEPROM checksum by reading/adding each word of the EEPROM
    316 * and then verifies that the sum of the EEPROM is equal to 0xBABA.
    317 */
    318static s32 igc_validate_nvm_checksum_i225(struct igc_hw *hw)
    319{
    320	s32 (*read_op_ptr)(struct igc_hw *hw, u16 offset, u16 count,
    321			   u16 *data);
    322	s32 status = 0;
    323
    324	status = hw->nvm.ops.acquire(hw);
    325	if (status)
    326		goto out;
    327
    328	/* Replace the read function with semaphore grabbing with
    329	 * the one that skips this for a while.
    330	 * We have semaphore taken already here.
    331	 */
    332	read_op_ptr = hw->nvm.ops.read;
    333	hw->nvm.ops.read = igc_read_nvm_eerd;
    334
    335	status = igc_validate_nvm_checksum(hw);
    336
    337	/* Revert original read operation. */
    338	hw->nvm.ops.read = read_op_ptr;
    339
    340	hw->nvm.ops.release(hw);
    341
    342out:
    343	return status;
    344}
    345
    346/**
    347 * igc_pool_flash_update_done_i225 - Pool FLUDONE status
    348 * @hw: pointer to the HW structure
    349 */
    350static s32 igc_pool_flash_update_done_i225(struct igc_hw *hw)
    351{
    352	s32 ret_val = -IGC_ERR_NVM;
    353	u32 i, reg;
    354
    355	for (i = 0; i < IGC_FLUDONE_ATTEMPTS; i++) {
    356		reg = rd32(IGC_EECD);
    357		if (reg & IGC_EECD_FLUDONE_I225) {
    358			ret_val = 0;
    359			break;
    360		}
    361		udelay(5);
    362	}
    363
    364	return ret_val;
    365}
    366
    367/**
    368 * igc_update_flash_i225 - Commit EEPROM to the flash
    369 * @hw: pointer to the HW structure
    370 */
    371static s32 igc_update_flash_i225(struct igc_hw *hw)
    372{
    373	s32 ret_val = 0;
    374	u32 flup;
    375
    376	ret_val = igc_pool_flash_update_done_i225(hw);
    377	if (ret_val == -IGC_ERR_NVM) {
    378		hw_dbg("Flash update time out\n");
    379		goto out;
    380	}
    381
    382	flup = rd32(IGC_EECD) | IGC_EECD_FLUPD_I225;
    383	wr32(IGC_EECD, flup);
    384
    385	ret_val = igc_pool_flash_update_done_i225(hw);
    386	if (ret_val)
    387		hw_dbg("Flash update time out\n");
    388	else
    389		hw_dbg("Flash update complete\n");
    390
    391out:
    392	return ret_val;
    393}
    394
    395/**
    396 * igc_update_nvm_checksum_i225 - Update EEPROM checksum
    397 * @hw: pointer to the HW structure
    398 *
    399 * Updates the EEPROM checksum by reading/adding each word of the EEPROM
    400 * up to the checksum.  Then calculates the EEPROM checksum and writes the
    401 * value to the EEPROM. Next commit EEPROM data onto the Flash.
    402 */
    403static s32 igc_update_nvm_checksum_i225(struct igc_hw *hw)
    404{
    405	u16 checksum = 0;
    406	s32 ret_val = 0;
    407	u16 i, nvm_data;
    408
    409	/* Read the first word from the EEPROM. If this times out or fails, do
    410	 * not continue or we could be in for a very long wait while every
    411	 * EEPROM read fails
    412	 */
    413	ret_val = igc_read_nvm_eerd(hw, 0, 1, &nvm_data);
    414	if (ret_val) {
    415		hw_dbg("EEPROM read failed\n");
    416		goto out;
    417	}
    418
    419	ret_val = hw->nvm.ops.acquire(hw);
    420	if (ret_val)
    421		goto out;
    422
    423	/* Do not use hw->nvm.ops.write, hw->nvm.ops.read
    424	 * because we do not want to take the synchronization
    425	 * semaphores twice here.
    426	 */
    427
    428	for (i = 0; i < NVM_CHECKSUM_REG; i++) {
    429		ret_val = igc_read_nvm_eerd(hw, i, 1, &nvm_data);
    430		if (ret_val) {
    431			hw->nvm.ops.release(hw);
    432			hw_dbg("NVM Read Error while updating checksum.\n");
    433			goto out;
    434		}
    435		checksum += nvm_data;
    436	}
    437	checksum = (u16)NVM_SUM - checksum;
    438	ret_val = igc_write_nvm_srwr(hw, NVM_CHECKSUM_REG, 1,
    439				     &checksum);
    440	if (ret_val) {
    441		hw->nvm.ops.release(hw);
    442		hw_dbg("NVM Write Error while updating checksum.\n");
    443		goto out;
    444	}
    445
    446	hw->nvm.ops.release(hw);
    447
    448	ret_val = igc_update_flash_i225(hw);
    449
    450out:
    451	return ret_val;
    452}
    453
    454/**
    455 * igc_get_flash_presence_i225 - Check if flash device is detected
    456 * @hw: pointer to the HW structure
    457 */
    458bool igc_get_flash_presence_i225(struct igc_hw *hw)
    459{
    460	bool ret_val = false;
    461	u32 eec = 0;
    462
    463	eec = rd32(IGC_EECD);
    464	if (eec & IGC_EECD_FLASH_DETECTED_I225)
    465		ret_val = true;
    466
    467	return ret_val;
    468}
    469
    470/**
    471 * igc_init_nvm_params_i225 - Init NVM func ptrs.
    472 * @hw: pointer to the HW structure
    473 */
    474s32 igc_init_nvm_params_i225(struct igc_hw *hw)
    475{
    476	struct igc_nvm_info *nvm = &hw->nvm;
    477
    478	nvm->ops.acquire = igc_acquire_nvm_i225;
    479	nvm->ops.release = igc_release_nvm_i225;
    480
    481	/* NVM Function Pointers */
    482	if (igc_get_flash_presence_i225(hw)) {
    483		nvm->ops.read = igc_read_nvm_srrd_i225;
    484		nvm->ops.write = igc_write_nvm_srwr_i225;
    485		nvm->ops.validate = igc_validate_nvm_checksum_i225;
    486		nvm->ops.update = igc_update_nvm_checksum_i225;
    487	} else {
    488		nvm->ops.read = igc_read_nvm_eerd;
    489		nvm->ops.write = NULL;
    490		nvm->ops.validate = NULL;
    491		nvm->ops.update = NULL;
    492	}
    493	return 0;
    494}
    495
    496/**
    497 *  igc_set_eee_i225 - Enable/disable EEE support
    498 *  @hw: pointer to the HW structure
    499 *  @adv2p5G: boolean flag enabling 2.5G EEE advertisement
    500 *  @adv1G: boolean flag enabling 1G EEE advertisement
    501 *  @adv100M: boolean flag enabling 100M EEE advertisement
    502 *
    503 *  Enable/disable EEE based on setting in dev_spec structure.
    504 **/
    505s32 igc_set_eee_i225(struct igc_hw *hw, bool adv2p5G, bool adv1G,
    506		     bool adv100M)
    507{
    508	u32 ipcnfg, eeer;
    509
    510	ipcnfg = rd32(IGC_IPCNFG);
    511	eeer = rd32(IGC_EEER);
    512
    513	/* enable or disable per user setting */
    514	if (hw->dev_spec._base.eee_enable) {
    515		u32 eee_su = rd32(IGC_EEE_SU);
    516
    517		if (adv100M)
    518			ipcnfg |= IGC_IPCNFG_EEE_100M_AN;
    519		else
    520			ipcnfg &= ~IGC_IPCNFG_EEE_100M_AN;
    521
    522		if (adv1G)
    523			ipcnfg |= IGC_IPCNFG_EEE_1G_AN;
    524		else
    525			ipcnfg &= ~IGC_IPCNFG_EEE_1G_AN;
    526
    527		if (adv2p5G)
    528			ipcnfg |= IGC_IPCNFG_EEE_2_5G_AN;
    529		else
    530			ipcnfg &= ~IGC_IPCNFG_EEE_2_5G_AN;
    531
    532		eeer |= (IGC_EEER_TX_LPI_EN | IGC_EEER_RX_LPI_EN |
    533			 IGC_EEER_LPI_FC);
    534
    535		/* This bit should not be set in normal operation. */
    536		if (eee_su & IGC_EEE_SU_LPI_CLK_STP)
    537			hw_dbg("LPI Clock Stop Bit should not be set!\n");
    538	} else {
    539		ipcnfg &= ~(IGC_IPCNFG_EEE_2_5G_AN | IGC_IPCNFG_EEE_1G_AN |
    540			    IGC_IPCNFG_EEE_100M_AN);
    541		eeer &= ~(IGC_EEER_TX_LPI_EN | IGC_EEER_RX_LPI_EN |
    542			  IGC_EEER_LPI_FC);
    543	}
    544	wr32(IGC_IPCNFG, ipcnfg);
    545	wr32(IGC_EEER, eeer);
    546	rd32(IGC_IPCNFG);
    547	rd32(IGC_EEER);
    548
    549	return IGC_SUCCESS;
    550}
    551
    552/* igc_set_ltr_i225 - Set Latency Tolerance Reporting thresholds
    553 * @hw: pointer to the HW structure
    554 * @link: bool indicating link status
    555 *
    556 * Set the LTR thresholds based on the link speed (Mbps), EEE, and DMAC
    557 * settings, otherwise specify that there is no LTR requirement.
    558 */
    559s32 igc_set_ltr_i225(struct igc_hw *hw, bool link)
    560{
    561	u32 tw_system, ltrc, ltrv, ltr_min, ltr_max, scale_min, scale_max;
    562	u16 speed, duplex;
    563	s32 size;
    564
    565	/* If we do not have link, LTR thresholds are zero. */
    566	if (link) {
    567		hw->mac.ops.get_speed_and_duplex(hw, &speed, &duplex);
    568
    569		/* Check if using copper interface with EEE enabled or if the
    570		 * link speed is 10 Mbps.
    571		 */
    572		if (hw->dev_spec._base.eee_enable &&
    573		    speed != SPEED_10) {
    574			/* EEE enabled, so send LTRMAX threshold. */
    575			ltrc = rd32(IGC_LTRC) |
    576			       IGC_LTRC_EEEMS_EN;
    577			wr32(IGC_LTRC, ltrc);
    578
    579			/* Calculate tw_system (nsec). */
    580			if (speed == SPEED_100) {
    581				tw_system = ((rd32(IGC_EEE_SU) &
    582					     IGC_TW_SYSTEM_100_MASK) >>
    583					     IGC_TW_SYSTEM_100_SHIFT) * 500;
    584			} else {
    585				tw_system = (rd32(IGC_EEE_SU) &
    586					     IGC_TW_SYSTEM_1000_MASK) * 500;
    587			}
    588		} else {
    589			tw_system = 0;
    590		}
    591
    592		/* Get the Rx packet buffer size. */
    593		size = rd32(IGC_RXPBS) &
    594		       IGC_RXPBS_SIZE_I225_MASK;
    595
    596		/* Calculations vary based on DMAC settings. */
    597		if (rd32(IGC_DMACR) & IGC_DMACR_DMAC_EN) {
    598			size -= (rd32(IGC_DMACR) &
    599				 IGC_DMACR_DMACTHR_MASK) >>
    600				 IGC_DMACR_DMACTHR_SHIFT;
    601			/* Convert size to bits. */
    602			size *= 1024 * 8;
    603		} else {
    604			/* Convert size to bytes, subtract the MTU, and then
    605			 * convert the size to bits.
    606			 */
    607			size *= 1024;
    608			size *= 8;
    609		}
    610
    611		if (size < 0) {
    612			hw_dbg("Invalid effective Rx buffer size %d\n",
    613			       size);
    614			return -IGC_ERR_CONFIG;
    615		}
    616
    617		/* Calculate the thresholds. Since speed is in Mbps, simplify
    618		 * the calculation by multiplying size/speed by 1000 for result
    619		 * to be in nsec before dividing by the scale in nsec. Set the
    620		 * scale such that the LTR threshold fits in the register.
    621		 */
    622		ltr_min = (1000 * size) / speed;
    623		ltr_max = ltr_min + tw_system;
    624		scale_min = (ltr_min / 1024) < 1024 ? IGC_LTRMINV_SCALE_1024 :
    625			    IGC_LTRMINV_SCALE_32768;
    626		scale_max = (ltr_max / 1024) < 1024 ? IGC_LTRMAXV_SCALE_1024 :
    627			    IGC_LTRMAXV_SCALE_32768;
    628		ltr_min /= scale_min == IGC_LTRMINV_SCALE_1024 ? 1024 : 32768;
    629		ltr_min -= 1;
    630		ltr_max /= scale_max == IGC_LTRMAXV_SCALE_1024 ? 1024 : 32768;
    631		ltr_max -= 1;
    632
    633		/* Only write the LTR thresholds if they differ from before. */
    634		ltrv = rd32(IGC_LTRMINV);
    635		if (ltr_min != (ltrv & IGC_LTRMINV_LTRV_MASK)) {
    636			ltrv = IGC_LTRMINV_LSNP_REQ | ltr_min |
    637			       (scale_min << IGC_LTRMINV_SCALE_SHIFT);
    638			wr32(IGC_LTRMINV, ltrv);
    639		}
    640
    641		ltrv = rd32(IGC_LTRMAXV);
    642		if (ltr_max != (ltrv & IGC_LTRMAXV_LTRV_MASK)) {
    643			ltrv = IGC_LTRMAXV_LSNP_REQ | ltr_max |
    644			       (scale_max << IGC_LTRMAXV_SCALE_SHIFT);
    645			wr32(IGC_LTRMAXV, ltrv);
    646		}
    647	}
    648
    649	return IGC_SUCCESS;
    650}