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iwlwifi: document txpower calculations 

Document txpower calculations

Signed-off-by: Ben Cahill <ben.m.cahill@intel.com>
Signed-off-by: Zhu Yi <yi.zhu@intel.com>
Signed-off-by: John W. Linville <linville@tuxdriver.com>
This commit is contained in:
Ben Cahill 2007-11-29 11:10:02 +08:00 committed by David S. Miller
parent 5991b419f0
commit 0c434c5a7f
2 changed files with 579 additions and 33 deletions
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609
drivers/net/wireless/iwlwifi/iwl-4965-hw.h
View File

@ -647,7 +647,7 @@ static inline int iwl4965_hw_valid_rtc_data_addr(u32 addr)
/********************* START TEMPERATURE *************************************/
/*
/**
* 4965 temperature calculation.
*
* The driver must calculate the device temperature before calculating
@ -693,6 +693,584 @@ static inline int iwl4965_hw_valid_rtc_data_addr(u32 addr)
/********************* START TXPOWER *****************************************/
/**
* 4965 txpower calculations rely on information from three sources:
*
* 1) EEPROM
* 2) "initialize" alive notification
* 3) statistics notifications
*
* EEPROM data consists of:
*
* 1) Regulatory information (max txpower and channel usage flags) is provided
* separately for each channel that can possibly supported by 4965.
* 40 MHz wide (.11n fat) channels are listed separately from 20 MHz
* (legacy) channels.
*
* See struct iwl4965_eeprom_channel for format, and struct iwl4965_eeprom
* for locations in EEPROM.
*
* 2) Factory txpower calibration information is provided separately for
* sub-bands of contiguous channels. 2.4GHz has just one sub-band,
* but 5 GHz has several sub-bands.
*
* In addition, per-band (2.4 and 5 Ghz) saturation txpowers are provided.
*
* See struct iwl4965_eeprom_calib_info (and the tree of structures
* contained within it) for format, and struct iwl4965_eeprom for
* locations in EEPROM.
*
* "Initialization alive" notification (see struct iwl4965_init_alive_resp)
* consists of:
*
* 1) Temperature calculation parameters.
*
* 2) Power supply voltage measurement.
*
* 3) Tx gain compensation to balance 2 transmitters for MIMO use.
*
* Statistics notifications deliver:
*
* 1) Current values for temperature param R4.
*/
/**
* To calculate a txpower setting for a given desired target txpower, channel,
* modulation bit rate, and transmitter chain (4965 has 2 transmitters to
* support MIMO and transmit diversity), driver must do the following:
*
* 1) Compare desired txpower vs. (EEPROM) regulatory limit for this channel.
* Do not exceed regulatory limit; reduce target txpower if necessary.
*
* If setting up txpowers for MIMO rates (rate indexes 8-15, 24-31),
* 2 transmitters will be used simultaneously; driver must reduce the
* regulatory limit by 3 dB (half-power) for each transmitter, so the
* combined total output of the 2 transmitters is within regulatory limits.
*
*
* 2) Compare target txpower vs. (EEPROM) saturation txpower *reduced by
* backoff for this bit rate*. Do not exceed (saturation - backoff[rate]);
* reduce target txpower if necessary.
*
* Backoff values below are in 1/2 dB units (equivalent to steps in
* txpower gain tables):
*
* OFDM 6 - 36 MBit: 10 steps (5 dB)
* OFDM 48 MBit: 15 steps (7.5 dB)
* OFDM 54 MBit: 17 steps (8.5 dB)
* OFDM 60 MBit: 20 steps (10 dB)
* CCK all rates: 10 steps (5 dB)
*
* Backoff values apply to saturation txpower on a per-transmitter basis;
* when using MIMO (2 transmitters), each transmitter uses the same
* saturation level provided in EEPROM, and the same backoff values;
* no reduction (such as with regulatory txpower limits) is required.
*
* Saturation and Backoff values apply equally to 20 Mhz (legacy) channel
* widths and 40 Mhz (.11n fat) channel widths; there is no separate
* factory measurement for fat channels.
*
* The result of this step is the final target txpower. The rest of
* the steps figure out the proper settings for the device to achieve
* that target txpower.
*
*
* 3) Determine (EEPROM) calibration subband for the target channel, by
* comparing against first and last channels in each subband
* (see struct iwl4965_eeprom_calib_subband_info).
*
*
* 4) Linearly interpolate (EEPROM) factory calibration measurement sets,
* referencing the 2 factory-measured (sample) channels within the subband.
*
* Interpolation is based on difference between target channel's frequency
* and the sample channels' frequencies. Since channel numbers are based
* on frequency (5 MHz between each channel number), this is equivalent
* to interpolating based on channel number differences.
*
* Note that the sample channels may or may not be the channels at the
* edges of the subband. The target channel may be "outside" of the
* span of the sampled channels.
*
* Driver may choose the pair (for 2 Tx chains) of measurements (see
* struct iwl4965_eeprom_calib_ch_info) for which the actual measured
* txpower comes closest to the desired txpower. Usually, though,
* the middle set of measurements is closest to the regulatory limits,
* and is therefore a good choice for all txpower calculations (this
* assumes that high accuracy is needed for maximizing legal txpower,
* while lower txpower configurations do not need as much accuracy).
*
* Driver should interpolate both members of the chosen measurement pair,
* i.e. for both Tx chains (radio transmitters), unless the driver knows
* that only one of the chains will be used (e.g. only one tx antenna
* connected, but this should be unusual). The rate scaling algorithm
* switches antennas to find best performance, so both Tx chains will
* be used (although only one at a time) even for non-MIMO transmissions.
*
* Driver should interpolate factory values for temperature, gain table
* index, and actual power. The power amplifier detector values are
* not used by the driver.
*
* Sanity check: If the target channel happens to be one of the sample
* channels, the results should agree with the sample channel's
* measurements!
*
*
* 5) Find difference between desired txpower and (interpolated)
* factory-measured txpower. Using (interpolated) factory gain table index
* (shown elsewhere) as a starting point, adjust this index lower to
* increase txpower, or higher to decrease txpower, until the target
* txpower is reached. Each step in the gain table is 1/2 dB.
*
* For example, if factory measured txpower is 16 dBm, and target txpower
* is 13 dBm, add 6 steps to the factory gain index to reduce txpower
* by 3 dB.
*
*
* 6) Find difference between current device temperature and (interpolated)
* factory-measured temperature for sub-band. Factory values are in
* degrees Celsius. To calculate current temperature, see comments for
* "4965 temperature calculation".
*
* If current temperature is higher than factory temperature, driver must
* increase gain (lower gain table index), and vice versa.
*
* Temperature affects gain differently for different channels:
*
* 2.4 GHz all channels: 3.5 degrees per half-dB step
* 5 GHz channels 34-43: 4.5 degrees per half-dB step
* 5 GHz channels >= 44: 4.0 degrees per half-dB step
*
* NOTE: Temperature can increase rapidly when transmitting, especially
* with heavy traffic at high txpowers. Driver should update
* temperature calculations often under these conditions to
* maintain strong txpower in the face of rising temperature.
*
*
* 7) Find difference between current power supply voltage indicator
* (from "initialize alive") and factory-measured power supply voltage
* indicator (EEPROM).
*
* If the current voltage is higher (indicator is lower) than factory
* voltage, gain should be reduced (gain table index increased) by:
*
* (eeprom - current) / 7
*
* If the current voltage is lower (indicator is higher) than factory
* voltage, gain should be increased (gain table index decreased) by:
*
* 2 * (current - eeprom) / 7
*
* If number of index steps in either direction turns out to be > 2,
* something is wrong ... just use 0.
*
* NOTE: Voltage compensation is independent of band/channel.
*
* NOTE: "Initialize" uCode measures current voltage, which is assumed
* to be constant after this initial measurement. Voltage
* compensation for txpower (number of steps in gain table)
* may be calculated once and used until the next uCode bootload.
*
*
* 8) If setting up txpowers for MIMO rates (rate indexes 8-15, 24-31),
* adjust txpower for each transmitter chain, so txpower is balanced
* between the two chains. There are 5 pairs of tx_atten[group][chain]
* values in "initialize alive", one pair for each of 5 channel ranges:
*
* Group 0: 5 GHz channel 34-43
* Group 1: 5 GHz channel 44-70
* Group 2: 5 GHz channel 71-124
* Group 3: 5 GHz channel 125-200
* Group 4: 2.4 GHz all channels
*
* Add the tx_atten[group][chain] value to the index for the target chain.
* The values are signed, but are in pairs of 0 and a non-negative number,
* so as to reduce gain (if necessary) of the "hotter" channel. This
* avoids any need to double-check for regulatory compliance after
* this step.
*
*
* 9) If setting up for a CCK rate, lower the gain by adding a CCK compensation
* value to the index:
*
* Hardware rev B: 9 steps (4.5 dB)
* Hardware rev C: 5 steps (2.5 dB)
*
* Hardware rev for 4965 can be determined by reading CSR_HW_REV_WA_REG,
* bits [3:2], 1 = B, 2 = C.
*
* NOTE: This compensation is in addition to any saturation backoff that
* might have been applied in an earlier step.
*
*
* 10) Select the gain table, based on band (2.4 vs 5 GHz).
*
* Limit the adjusted index to stay within the table!
*
*
* 11) Read gain table entries for DSP and radio gain, place into appropriate
* location(s) in command (struct iwl4965_txpowertable_cmd).
*/
/* Limit range of txpower output target to be between these values */
#define IWL_TX_POWER_TARGET_POWER_MIN (0) /* 0 dBm = 1 milliwatt */
#define IWL_TX_POWER_TARGET_POWER_MAX (16) /* 16 dBm */
/**
* When MIMO is used (2 transmitters operating simultaneously), driver should
* limit each transmitter to deliver a max of 3 dB below the regulatory limit
* for the device. That is, use half power for each transmitter, so total
* txpower is within regulatory limits.
*
* The value "6" represents number of steps in gain table to reduce power 3 dB.
* Each step is 1/2 dB.
*/
#define IWL_TX_POWER_MIMO_REGULATORY_COMPENSATION (6)
/**
* CCK gain compensation.
*
* When calculating txpowers for CCK, after making sure that the target power
* is within regulatory and saturation limits, driver must additionally
* back off gain by adding these values to the gain table index.
*
* Hardware rev for 4965 can be determined by reading CSR_HW_REV_WA_REG,
* bits [3:2], 1 = B, 2 = C.
*/
#define IWL_TX_POWER_CCK_COMPENSATION_B_STEP (9)
#define IWL_TX_POWER_CCK_COMPENSATION_C_STEP (5)
/*
* 4965 power supply voltage compensation for txpower
*/
#define TX_POWER_IWL_VOLTAGE_CODES_PER_03V (7)
/**
* Gain tables.
*
* The following tables contain pair of values for setting txpower, i.e.
* gain settings for the output of the device's digital signal processor (DSP),
* and for the analog gain structure of the transmitter.
*
* Each entry in the gain tables represents a step of 1/2 dB. Note that these
* are *relative* steps, not indications of absolute output power. Output
* power varies with temperature, voltage, and channel frequency, and also
* requires consideration of average power (to satisfy regulatory constraints),
* and peak power (to avoid distortion of the output signal).
*
* Each entry contains two values:
* 1) DSP gain (or sometimes called DSP attenuation). This is a fine-grained
* linear value that multiplies the output of the digital signal processor,
* before being sent to the analog radio.
* 2) Radio gain. This sets the analog gain of the radio Tx path.
* It is a coarser setting, and behaves in a logarithmic (dB) fashion.
*
* EEPROM contains factory calibration data for txpower. This maps actual
* measured txpower levels to gain settings in the "well known" tables
* below ("well-known" means here that both factory calibration *and* the
* driver work with the same table).
*
* There are separate tables for 2.4 GHz and 5 GHz bands. The 5 GHz table
* has an extension (into negative indexes), in case the driver needs to
* boost power setting for high device temperatures (higher than would be
* present during factory calibration). A 5 Ghz EEPROM index of "40"
* corresponds to the 49th entry in the table used by the driver.
*/
#define MIN_TX_GAIN_INDEX (0) /* highest gain, lowest idx, 2.4 */
#define MIN_TX_GAIN_INDEX_52GHZ_EXT (-9) /* highest gain, lowest idx, 5 */
/**
* 2.4 GHz gain table
*
* Index Dsp gain Radio gain
* 0 110 0x3f (highest gain)
* 1 104 0x3f
* 2 98 0x3f
* 3 110 0x3e
* 4 104 0x3e
* 5 98 0x3e
* 6 110 0x3d
* 7 104 0x3d
* 8 98 0x3d
* 9 110 0x3c
* 10 104 0x3c
* 11 98 0x3c
* 12 110 0x3b
* 13 104 0x3b
* 14 98 0x3b
* 15 110 0x3a
* 16 104 0x3a
* 17 98 0x3a
* 18 110 0x39
* 19 104 0x39
* 20 98 0x39
* 21 110 0x38
* 22 104 0x38
* 23 98 0x38
* 24 110 0x37
* 25 104 0x37
* 26 98 0x37
* 27 110 0x36
* 28 104 0x36
* 29 98 0x36
* 30 110 0x35
* 31 104 0x35
* 32 98 0x35
* 33 110 0x34
* 34 104 0x34
* 35 98 0x34
* 36 110 0x33
* 37 104 0x33
* 38 98 0x33
* 39 110 0x32
* 40 104 0x32
* 41 98 0x32
* 42 110 0x31
* 43 104 0x31
* 44 98 0x31
* 45 110 0x30
* 46 104 0x30
* 47 98 0x30
* 48 110 0x6
* 49 104 0x6
* 50 98 0x6
* 51 110 0x5
* 52 104 0x5
* 53 98 0x5
* 54 110 0x4
* 55 104 0x4
* 56 98 0x4
* 57 110 0x3
* 58 104 0x3
* 59 98 0x3
* 60 110 0x2
* 61 104 0x2
* 62 98 0x2
* 63 110 0x1
* 64 104 0x1
* 65 98 0x1
* 66 110 0x0
* 67 104 0x0
* 68 98 0x0
* 69 97 0
* 70 96 0
* 71 95 0
* 72 94 0
* 73 93 0
* 74 92 0
* 75 91 0
* 76 90 0
* 77 89 0
* 78 88 0
* 79 87 0
* 80 86 0
* 81 85 0
* 82 84 0
* 83 83 0
* 84 82 0
* 85 81 0
* 86 80 0
* 87 79 0
* 88 78 0
* 89 77 0
* 90 76 0
* 91 75 0
* 92 74 0
* 93 73 0
* 94 72 0
* 95 71 0
* 96 70 0
* 97 69 0
* 98 68 0
*/
/**
* 5 GHz gain table
*
* Index Dsp gain Radio gain
* -9 123 0x3F (highest gain)
* -8 117 0x3F
* -7 110 0x3F
* -6 104 0x3F
* -5 98 0x3F
* -4 110 0x3E
* -3 104 0x3E
* -2 98 0x3E
* -1 110 0x3D
* 0 104 0x3D
* 1 98 0x3D
* 2 110 0x3C
* 3 104 0x3C
* 4 98 0x3C
* 5 110 0x3B
* 6 104 0x3B
* 7 98 0x3B
* 8 110 0x3A
* 9 104 0x3A
* 10 98 0x3A
* 11 110 0x39
* 12 104 0x39
* 13 98 0x39
* 14 110 0x38
* 15 104 0x38
* 16 98 0x38
* 17 110 0x37
* 18 104 0x37
* 19 98 0x37
* 20 110 0x36
* 21 104 0x36
* 22 98 0x36
* 23 110 0x35
* 24 104 0x35
* 25 98 0x35
* 26 110 0x34
* 27 104 0x34
* 28 98 0x34
* 29 110 0x33
* 30 104 0x33
* 31 98 0x33
* 32 110 0x32
* 33 104 0x32
* 34 98 0x32
* 35 110 0x31
* 36 104 0x31
* 37 98 0x31
* 38 110 0x30
* 39 104 0x30
* 40 98 0x30
* 41 110 0x25
* 42 104 0x25
* 43 98 0x25
* 44 110 0x24
* 45 104 0x24
* 46 98 0x24
* 47 110 0x23
* 48 104 0x23
* 49 98 0x23
* 50 110 0x22
* 51 104 0x18
* 52 98 0x18
* 53 110 0x17
* 54 104 0x17
* 55 98 0x17
* 56 110 0x16
* 57 104 0x16
* 58 98 0x16
* 59 110 0x15
* 60 104 0x15
* 61 98 0x15
* 62 110 0x14
* 63 104 0x14
* 64 98 0x14
* 65 110 0x13
* 66 104 0x13
* 67 98 0x13
* 68 110 0x12
* 69 104 0x08
* 70 98 0x08
* 71 110 0x07
* 72 104 0x07
* 73 98 0x07
* 74 110 0x06
* 75 104 0x06
* 76 98 0x06
* 77 110 0x05
* 78 104 0x05
* 79 98 0x05
* 80 110 0x04
* 81 104 0x04
* 82 98 0x04
* 83 110 0x03
* 84 104 0x03
* 85 98 0x03
* 86 110 0x02
* 87 104 0x02
* 88 98 0x02
* 89 110 0x01
* 90 104 0x01
* 91 98 0x01
* 92 110 0x00
* 93 104 0x00
* 94 98 0x00
* 95 93 0x00
* 96 88 0x00
* 97 83 0x00
* 98 78 0x00
*/
/**
* Sanity checks and default values for EEPROM regulatory levels.
* If EEPROM values fall outside MIN/MAX range, use default values.
*
* Regulatory limits refer to the maximum average txpower allowed by
* regulatory agencies in the geographies in which the device is meant
* to be operated. These limits are SKU-specific (i.e. geography-specific),
* and channel-specific; each channel has an individual regulatory limit
* listed in the EEPROM.
*
* Units are in half-dBm (i.e. "34" means 17 dBm).
*/
#define IWL_TX_POWER_DEFAULT_REGULATORY_24 (34)
#define IWL_TX_POWER_DEFAULT_REGULATORY_52 (34)
#define IWL_TX_POWER_REGULATORY_MIN (0)
#define IWL_TX_POWER_REGULATORY_MAX (34)
/**
* Sanity checks and default values for EEPROM saturation levels.
* If EEPROM values fall outside MIN/MAX range, use default values.
*
* Saturation is the highest level that the output power amplifier can produce
* without significant clipping distortion. This is a "peak" power level.
* Different types of modulation (i.e. various "rates", and OFDM vs. CCK)
* require differing amounts of backoff, relative to their average power output,
* in order to avoid clipping distortion.
*
* Driver must make sure that it is violating neither the saturation limit,
* nor the regulatory limit, when calculating Tx power settings for various
* rates.
*
* Units are in half-dBm (i.e. "38" means 19 dBm).
*/
#define IWL_TX_POWER_DEFAULT_SATURATION_24 (38)
#define IWL_TX_POWER_DEFAULT_SATURATION_52 (38)
#define IWL_TX_POWER_SATURATION_MIN (20)
#define IWL_TX_POWER_SATURATION_MAX (50)
/**
* Channel groups used for Tx Attenuation calibration (MIMO tx channel balance)
* and thermal Txpower calibration.
*
* When calculating txpower, driver must compensate for current device
* temperature; higher temperature requires higher gain. Driver must calculate
* current temperature (see "4965 temperature calculation"), then compare vs.
* factory calibration temperature in EEPROM; if current temperature is higher
* than factory temperature, driver must *increase* gain by proportions shown
* in table below. If current temperature is lower than factory, driver must
* *decrease* gain.
*
* Different frequency ranges require different compensation, as shown below.
*/
/* Group 0, 5.2 GHz ch 34-43: 4.5 degrees per 1/2 dB. */
#define CALIB_IWL_TX_ATTEN_GR1_FCH 34
#define CALIB_IWL_TX_ATTEN_GR1_LCH 43
/* Group 1, 5.3 GHz ch 44-70: 4.0 degrees per 1/2 dB. */
#define CALIB_IWL_TX_ATTEN_GR2_FCH 44
#define CALIB_IWL_TX_ATTEN_GR2_LCH 70
/* Group 2, 5.5 GHz ch 71-124: 4.0 degrees per 1/2 dB. */
#define CALIB_IWL_TX_ATTEN_GR3_FCH 71
#define CALIB_IWL_TX_ATTEN_GR3_LCH 124
/* Group 3, 5.7 GHz ch 125-200: 4.0 degrees per 1/2 dB. */
#define CALIB_IWL_TX_ATTEN_GR4_FCH 125
#define CALIB_IWL_TX_ATTEN_GR4_LCH 200
/* Group 4, 2.4 GHz all channels: 3.5 degrees per 1/2 dB. */
#define CALIB_IWL_TX_ATTEN_GR5_FCH 1
#define CALIB_IWL_TX_ATTEN_GR5_LCH 20
enum {
CALIB_CH_GROUP_1 = 0,
CALIB_CH_GROUP_2 = 1,
@ -702,35 +1280,6 @@ enum {
CALIB_CH_GROUP_MAX
};
#define IWL_TX_POWER_MIMO_REGULATORY_COMPENSATION (6)
#define IWL_TX_POWER_TARGET_POWER_MIN (0) /* 0 dBm = 1 milliwatt */
#define IWL_TX_POWER_TARGET_POWER_MAX (16) /* 16 dBm */
#define MIN_TX_GAIN_INDEX (0)
#define MIN_TX_GAIN_INDEX_52GHZ_EXT (-9)
#define IWL_TX_POWER_DEFAULT_REGULATORY_24 (34)
#define IWL_TX_POWER_DEFAULT_REGULATORY_52 (34)
#define IWL_TX_POWER_REGULATORY_MIN (0)
#define IWL_TX_POWER_REGULATORY_MAX (34)
#define IWL_TX_POWER_DEFAULT_SATURATION_24 (38)
#define IWL_TX_POWER_DEFAULT_SATURATION_52 (38)
#define IWL_TX_POWER_SATURATION_MIN (20)
#define IWL_TX_POWER_SATURATION_MAX (50)
/* First and last channels of all groups */
#define CALIB_IWL_TX_ATTEN_GR1_FCH 34
#define CALIB_IWL_TX_ATTEN_GR1_LCH 43
#define CALIB_IWL_TX_ATTEN_GR2_FCH 44
#define CALIB_IWL_TX_ATTEN_GR2_LCH 70
#define CALIB_IWL_TX_ATTEN_GR3_FCH 71
#define CALIB_IWL_TX_ATTEN_GR3_LCH 124
#define CALIB_IWL_TX_ATTEN_GR4_FCH 125
#define CALIB_IWL_TX_ATTEN_GR4_LCH 200
#define CALIB_IWL_TX_ATTEN_GR5_FCH 1
#define CALIB_IWL_TX_ATTEN_GR5_LCH 20
/********************* END TXPOWER *****************************************/
/* Flow Handler Definitions */

3
drivers/net/wireless/iwlwifi/iwl-4965.h
View File

@ -859,9 +859,6 @@ struct iwl4965_kw {
#define NUM_RX_CHAINS (3)
#define TX_POWER_IWL_ILLEGAL_VOLTAGE -10000
#define TX_POWER_IWL_VOLTAGE_CODES_PER_03V 7
#define IWL_TX_POWER_CCK_COMPENSATION_B_STEP (9)
#define IWL_TX_POWER_CCK_COMPENSATION_C_STEP (5)
struct iwl4965_traffic_load {
unsigned long time_stamp;