Gitweb:
http://git.kernel.org/git/?p=linux/kernel/git/torvalds/linux-2.6.git;a=commit;h=f7d09d7c453f197d802c50172b27170a43e1a816
Commit: f7d09d7c453f197d802c50172b27170a43e1a816
Parent: abceddb40728397fcfd0b295d7530920a606ab88
Author: Ben Cahill <[EMAIL PROTECTED]>
AuthorDate: Thu Nov 29 11:09:51 2007 +0800
Committer: David S. Miller <[EMAIL PROTECTED]>
CommitDate: Mon Jan 28 15:05:20 2008 -0800
iwlwifi: Document Rx calibration
Document Rx calibration
Signed-off-by: Ben Cahill <[EMAIL PROTECTED]>
Signed-off-by: Zhu Yi <[EMAIL PROTECTED]>
Signed-off-by: John W. Linville <[EMAIL PROTECTED]>
---
drivers/net/wireless/iwlwifi/iwl-4965-commands.h | 267 +++++++++++++++++++++-
drivers/net/wireless/iwlwifi/iwl-4965.c | 1 +
drivers/net/wireless/iwlwifi/iwl-4965.h | 18 --
3 files changed, 261 insertions(+), 25 deletions(-)
diff --git a/drivers/net/wireless/iwlwifi/iwl-4965-commands.h
b/drivers/net/wireless/iwlwifi/iwl-4965-commands.h
index 00d4ab7..575a065 100644
--- a/drivers/net/wireless/iwlwifi/iwl-4965-commands.h
+++ b/drivers/net/wireless/iwlwifi/iwl-4965-commands.h
@@ -1573,25 +1573,278 @@ struct iwl4965_missed_beacon_notif {
__le32 num_recvd_beacons;
} __attribute__ ((packed));
+
/******************************************************************************
* (11)
* Rx Calibration Commands:
*
+ * With the uCode used for open source drivers, most Tx calibration (except
+ * for Tx Power) and most Rx calibration is done by uCode during the
+ * "initialize" phase of uCode boot. Driver must calibrate only:
+ *
+ * 1) Tx power (depends on temperature), described elsewhere
+ * 2) Receiver gain balance (optimize MIMO, and detect disconnected antennas)
+ * 3) Receiver sensitivity (to optimize signal detection)
+ *
*****************************************************************************/
-#define PHY_CALIBRATE_DIFF_GAIN_CMD (7)
-#define HD_TABLE_SIZE (11)
+/**
+ * SENSITIVITY_CMD = 0xa8 (command, has simple generic response)
+ *
+ * This command sets up the Rx signal detector for a sensitivity level that
+ * is high enough to lock onto all signals within the associated network,
+ * but low enough to ignore signals that are below a certain threshold, so as
+ * not to have too many "false alarms". False alarms are signals that the
+ * Rx DSP tries to lock onto, but then discards after determining that they
+ * are noise.
+ *
+ * The optimum number of false alarms is between 5 and 50 per 200 TUs
+ * (200 * 1024 uSecs, i.e. 204.8 milliseconds) of actual Rx time (i.e.
+ * time listening, not transmitting). Driver must adjust sensitivity so that
+ * the ratio of actual false alarms to actual Rx time falls within this range.
+ *
+ * While associated, uCode delivers STATISTICS_NOTIFICATIONs after each
+ * received beacon. These provide information to the driver to analyze the
+ * sensitivity. Don't analyze statistics that come in from scanning, or any
+ * other non-associated-network source. Pertinent statistics include:
+ *
+ * From "general" statistics (struct statistics_rx_non_phy):
+ *
+ * (beacon_energy_[abc] & 0x0FF00) >> 8 (unsigned, higher value is lower level)
+ * Measure of energy of desired signal. Used for establishing a level
+ * below which the device does not detect signals.
+ *
+ * (beacon_silence_rssi_[abc] & 0x0FF00) >> 8 (unsigned, units in dB)
+ * Measure of background noise in silent period after beacon.
+ *
+ * channel_load
+ * uSecs of actual Rx time during beacon period (varies according to
+ * how much time was spent transmitting).
+ *
+ * From "cck" and "ofdm" statistics (struct statistics_rx_phy), separately:
+ *
+ * false_alarm_cnt
+ * Signal locks abandoned early (before phy-level header).
+ *
+ * plcp_err
+ * Signal locks abandoned late (during phy-level header).
+ *
+ * NOTE: Both false_alarm_cnt and plcp_err increment monotonically from
+ * beacon to beacon, i.e. each value is an accumulation of all errors
+ * before and including the latest beacon. Values will wrap around to 0
+ * after counting up to 2^32 - 1. Driver must differentiate vs.
+ * previous beacon's values to determine # false alarms in the current
+ * beacon period.
+ *
+ * Total number of false alarms = false_alarms + plcp_errs
+ *
+ * For OFDM, adjust the following table entries in struct iwl_sensitivity_cmd
+ * (notice that the start points for OFDM are at or close to settings for
+ * maximum sensitivity):
+ *
+ * START / MIN / MAX
+ * HD_AUTO_CORR32_X1_TH_ADD_MIN_INDEX 90 / 85 / 120
+ * HD_AUTO_CORR32_X1_TH_ADD_MIN_MRC_INDEX 170 / 170 / 210
+ * HD_AUTO_CORR32_X4_TH_ADD_MIN_INDEX 105 / 105 / 140
+ * HD_AUTO_CORR32_X4_TH_ADD_MIN_MRC_INDEX 220 / 220 / 270
+ *
+ * If actual rate of OFDM false alarms (+ plcp_errors) is too high
+ * (greater than 50 for each 204.8 msecs listening), reduce sensitivity
+ * by *adding* 1 to all 4 of the table entries above, up to the max for
+ * each entry. Conversely, if false alarm rate is too low (less than 5
+ * for each 204.8 msecs listening), *subtract* 1 from each entry to
+ * increase sensitivity.
+ *
+ * For CCK sensitivity, keep track of the following:
+ *
+ * 1). 20-beacon history of maximum background noise, indicated by
+ * (beacon_silence_rssi_[abc] & 0x0FF00), units in dB, across the
+ * 3 receivers. For any given beacon, the "silence reference" is
+ * the maximum of last 60 samples (20 beacons * 3 receivers).
+ *
+ * 2). 10-beacon history of strongest signal level, as indicated
+ * by (beacon_energy_[abc] & 0x0FF00) >> 8, across the 3 receivers,
+ * i.e. the strength of the signal through the best receiver at the
+ * moment. These measurements are "upside down", with lower values
+ * for stronger signals, so max energy will be *minimum* value.
+ *
+ * Then for any given beacon, the driver must determine the *weakest*
+ * of the strongest signals; this is the minimum level that needs to be
+ * successfully detected, when using the best receiver at the moment.
+ * "Max cck energy" is the maximum (higher value means lower energy!)
+ * of the last 10 minima. Once this is determined, driver must add
+ * a little margin by adding "6" to it.
+ *
+ * 3). Number of consecutive beacon periods with too few false alarms.
+ * Reset this to 0 at the first beacon period that falls within the
+ * "good" range (5 to 50 false alarms per 204.8 milliseconds rx).
+ *
+ * Then, adjust the following CCK table entries in struct iwl_sensitivity_cmd
+ * (notice that the start points for CCK are at maximum sensitivity):
+ *
+ * START / MIN / MAX
+ * HD_AUTO_CORR40_X4_TH_ADD_MIN_INDEX 125 / 125 / 200
+ * HD_AUTO_CORR40_X4_TH_ADD_MIN_MRC_INDEX 200 / 200 / 400
+ * HD_MIN_ENERGY_CCK_DET_INDEX 100 / 0 / 100
+ *
+ * If actual rate of CCK false alarms (+ plcp_errors) is too high
+ * (greater than 50 for each 204.8 msecs listening), method for reducing
+ * sensitivity is:
+ *
+ * 1) *Add* 3 to value in HD_AUTO_CORR40_X4_TH_ADD_MIN_MRC_INDEX,
+ * up to max 400.
+ *
+ * 2) If current value in HD_AUTO_CORR40_X4_TH_ADD_MIN_INDEX is < 160,
+ * sensitivity has been reduced a significant amount; bring it up to
+ * a moderate 161. Otherwise, *add* 3, up to max 200.
+ *
+ * 3) a) If current value in HD_AUTO_CORR40_X4_TH_ADD_MIN_INDEX is > 160,
+ * sensitivity has been reduced only a moderate or small amount;
+ * *subtract* 2 from value in HD_MIN_ENERGY_CCK_DET_INDEX,
+ * down to min 0. Otherwise (if gain has been significantly reduced),
+ * don't change the HD_MIN_ENERGY_CCK_DET_INDEX value.
+ *
+ * b) Save a snapshot of the "silence reference".
+ *
+ * If actual rate of CCK false alarms (+ plcp_errors) is too low
+ * (less than 5 for each 204.8 msecs listening), method for increasing
+ * sensitivity is used only if:
+ *
+ * 1a) Previous beacon did not have too many false alarms
+ * 1b) AND difference between previous "silence reference" and current
+ * "silence reference" (prev - current) is 2 or more,
+ * OR 2) 100 or more consecutive beacon periods have had rate of
+ * less than 5 false alarms per 204.8 milliseconds rx time.
+ *
+ * Method for increasing sensitivity:
+ *
+ * 1) *Subtract* 3 from value in HD_AUTO_CORR40_X4_TH_ADD_MIN_INDEX,
+ * down to min 125.
+ *
+ * 2) *Subtract* 3 from value in HD_AUTO_CORR40_X4_TH_ADD_MIN_MRC_INDEX,
+ * down to min 200.
+ *
+ * 3) *Add* 2 to value in HD_MIN_ENERGY_CCK_DET_INDEX, up to max 100.
+ *
+ * If actual rate of CCK false alarms (+ plcp_errors) is within good range
+ * (between 5 and 50 for each 204.8 msecs listening):
+ *
+ * 1) Save a snapshot of the silence reference.
+ *
+ * 2) If previous beacon had too many CCK false alarms (+ plcp_errors),
+ * give some extra margin to energy threshold by *subtracting* 8
+ * from value in HD_MIN_ENERGY_CCK_DET_INDEX.
+ *
+ * For all cases (too few, too many, good range), make sure that the CCK
+ * detection threshold (energy) is below the energy level for robust
+ * detection over the past 10 beacon periods, the "Max cck energy".
+ * Lower values mean higher energy; this means making sure that the value
+ * in HD_MIN_ENERGY_CCK_DET_INDEX is at or *above* "Max cck energy".
+ *
+ * Driver should set the following entries to fixed values:
+ *
+ * HD_MIN_ENERGY_OFDM_DET_INDEX 100
+ * HD_BARKER_CORR_TH_ADD_MIN_INDEX 190
+ * HD_BARKER_CORR_TH_ADD_MIN_MRC_INDEX 390
+ * HD_OFDM_ENERGY_TH_IN_INDEX 62
+ */
+
+/*
+ * Table entries in SENSITIVITY_CMD (struct iwl4965_sensitivity_cmd)
+ */
+#define HD_TABLE_SIZE (11) /* number of entries */
+#define HD_MIN_ENERGY_CCK_DET_INDEX (0) /* table
indexes */
+#define HD_MIN_ENERGY_OFDM_DET_INDEX (1)
+#define HD_AUTO_CORR32_X1_TH_ADD_MIN_INDEX (2)
+#define HD_AUTO_CORR32_X1_TH_ADD_MIN_MRC_INDEX (3)
+#define HD_AUTO_CORR40_X4_TH_ADD_MIN_MRC_INDEX (4)
+#define HD_AUTO_CORR32_X4_TH_ADD_MIN_INDEX (5)
+#define HD_AUTO_CORR32_X4_TH_ADD_MIN_MRC_INDEX (6)
+#define HD_BARKER_CORR_TH_ADD_MIN_INDEX (7)
+#define HD_BARKER_CORR_TH_ADD_MIN_MRC_INDEX (8)
+#define HD_AUTO_CORR40_X4_TH_ADD_MIN_INDEX (9)
+#define HD_OFDM_ENERGY_TH_IN_INDEX (10)
+
+/* Control field in struct iwl4965_sensitivity_cmd */
+#define SENSITIVITY_CMD_CONTROL_DEFAULT_TABLE __constant_cpu_to_le16(0)
+#define SENSITIVITY_CMD_CONTROL_WORK_TABLE __constant_cpu_to_le16(1)
+/**
+ * struct iwl4965_sensitivity_cmd
+ * @control: (1) updates working table, (0) updates default table
+ * @table: energy threshold values, use HD_* as index into table
+ *
+ * Always use "1" in "control" to update uCode's working table and DSP.
+ */
struct iwl4965_sensitivity_cmd {
- __le16 control;
- __le16 table[HD_TABLE_SIZE];
+ __le16 control; /* always use "1" */
+ __le16 table[HD_TABLE_SIZE]; /* use HD_* as index */
} __attribute__ ((packed));
+
+/**
+ * REPLY_PHY_CALIBRATION_CMD = 0xb0 (command, has simple generic response)
+ *
+ * This command sets the relative gains of 4965's 3 radio receiver chains.
+ *
+ * After the first association, driver should accumulate signal and noise
+ * statistics from the STATISTICS_NOTIFICATIONs that follow the first 20
+ * beacons from the associated network (don't collect statistics that come
+ * in from scanning, or any other non-network source).
+ *
+ * DISCONNECTED ANTENNA:
+ *
+ * Driver should determine which antennas are actually connected, by comparing
+ * average beacon signal levels for the 3 Rx chains. Accumulate (add) the
+ * following values over 20 beacons, one accumulator for each of the chains
+ * a/b/c, from struct statistics_rx_non_phy:
+ *
+ * beacon_rssi_[abc] & 0x0FF (unsigned, units in dB)
+ *
+ * Find the strongest signal from among a/b/c. Compare the other two to the
+ * strongest. If any signal is more than 15 dB (times 20, unless you
+ * divide the accumulated values by 20) below the strongest, the driver
+ * considers that antenna to be disconnected, and should not try to use that
+ * antenna/chain for Rx or Tx. If both A and B seem to be disconnected,
+ * driver should declare the stronger one as connected, and attempt to use it
+ * (A and B are the only 2 Tx chains!).
+ *
+ *
+ * RX BALANCE:
+ *
+ * Driver should balance the 3 receivers (but just the ones that are connected
+ * to antennas, see above) for gain, by comparing the average signal levels
+ * detected during the silence after each beacon (background noise).
+ * Accumulate (add) the following values over 20 beacons, one accumulator for
+ * each of the chains a/b/c, from struct statistics_rx_non_phy:
+ *
+ * beacon_silence_rssi_[abc] & 0x0FF (unsigned, units in dB)
+ *
+ * Find the weakest background noise level from among a/b/c. This Rx chain
+ * will be the reference, with 0 gain adjustment. Attenuate other channels by
+ * finding noise difference:
+ *
+ * (accum_noise[i] - accum_noise[reference]) / 30
+ *
+ * The "30" adjusts the dB in the 20 accumulated samples to units of 1.5 dB.
+ * For use in diff_gain_[abc] fields of struct iwl_calibration_cmd, the
+ * driver should limit the difference results to a range of 0-3 (0-4.5 dB),
+ * and set bit 2 to indicate "reduce gain". The value for the reference
+ * (weakest) chain should be "0".
+ *
+ * diff_gain_[abc] bit fields:
+ * 2: (1) reduce gain, (0) increase gain
+ * 1-0: amount of gain, units of 1.5 dB
+ */
+
+/* "Differential Gain" opcode used in REPLY_PHY_CALIBRATION_CMD. */
+#define PHY_CALIBRATE_DIFF_GAIN_CMD (7)
+
struct iwl4965_calibration_cmd {
- u8 opCode;
- u8 flags;
+ u8 opCode; /* PHY_CALIBRATE_DIFF_GAIN_CMD (7) */
+ u8 flags; /* not used */
__le16 reserved;
- s8 diff_gain_a;
+ s8 diff_gain_a; /* see above */
s8 diff_gain_b;
s8 diff_gain_c;
u8 reserved1;
diff --git a/drivers/net/wireless/iwlwifi/iwl-4965.c
b/drivers/net/wireless/iwlwifi/iwl-4965.c
index 7d95de9..d44166a 100644
--- a/drivers/net/wireless/iwlwifi/iwl-4965.c
+++ b/drivers/net/wireless/iwlwifi/iwl-4965.c
@@ -1068,6 +1068,7 @@ static int iwl4965_sensitivity_write(struct iwl4965_priv
*priv, u8 flags)
data->auto_corr_cck, data->auto_corr_cck_mrc,
data->nrg_th_cck);
+ /* Update uCode's "work" table, and copy it to DSP */
cmd.control = SENSITIVITY_CMD_CONTROL_WORK_TABLE;
if (flags & CMD_ASYNC)
diff --git a/drivers/net/wireless/iwlwifi/iwl-4965.h
b/drivers/net/wireless/iwlwifi/iwl-4965.h
index af34974..321767f 100644
--- a/drivers/net/wireless/iwlwifi/iwl-4965.h
+++ b/drivers/net/wireless/iwlwifi/iwl-4965.h
@@ -924,22 +924,6 @@ struct iwl4965_lq_mngr {
#define CAL_NUM_OF_BEACONS 20
#define MAXIMUM_ALLOWED_PATHLOSS 15
-/* Param table within SENSITIVITY_CMD */
-#define HD_MIN_ENERGY_CCK_DET_INDEX (0)
-#define HD_MIN_ENERGY_OFDM_DET_INDEX (1)
-#define HD_AUTO_CORR32_X1_TH_ADD_MIN_INDEX (2)
-#define HD_AUTO_CORR32_X1_TH_ADD_MIN_MRC_INDEX (3)
-#define HD_AUTO_CORR40_X4_TH_ADD_MIN_MRC_INDEX (4)
-#define HD_AUTO_CORR32_X4_TH_ADD_MIN_INDEX (5)
-#define HD_AUTO_CORR32_X4_TH_ADD_MIN_MRC_INDEX (6)
-#define HD_BARKER_CORR_TH_ADD_MIN_INDEX (7)
-#define HD_BARKER_CORR_TH_ADD_MIN_MRC_INDEX (8)
-#define HD_AUTO_CORR40_X4_TH_ADD_MIN_INDEX (9)
-#define HD_OFDM_ENERGY_TH_IN_INDEX (10)
-
-#define SENSITIVITY_CMD_CONTROL_DEFAULT_TABLE __constant_cpu_to_le16(0)
-#define SENSITIVITY_CMD_CONTROL_WORK_TABLE __constant_cpu_to_le16(1)
-
#define CHAIN_NOISE_MAX_DELTA_GAIN_CODE 3
#define MAX_FA_OFDM 50
@@ -967,8 +951,6 @@ struct iwl4965_lq_mngr {
#define AUTO_CORR_STEP_CCK 3
#define AUTO_CORR_MAX_TH_CCK 160
-#define NRG_ALG 0
-#define AUTO_CORR_ALG 1
#define NRG_DIFF 2
#define NRG_STEP_CCK 2
#define NRG_MARGIN 8
-
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