From 5991b419f04dee78c36d43de6b6ff2d27934d707 Mon Sep 17 00:00:00 2001 From: Ben Cahill Date: Thu, 29 Nov 2007 11:10:01 +0800 Subject: iwlwifi: document temperature calculation Document temperature calculation Signed-off-by: Ben Cahill Signed-off-by: Zhu Yi Signed-off-by: John W. Linville --- drivers/net/wireless/iwlwifi/iwl-4965-hw.h | 57 ++++++++++++++++++++++++------ 1 file changed, 46 insertions(+), 11 deletions(-) diff --git a/drivers/net/wireless/iwlwifi/iwl-4965-hw.h b/drivers/net/wireless/iwlwifi/iwl-4965-hw.h index 3c09225c662..78d9854f750 100644 --- a/drivers/net/wireless/iwlwifi/iwl-4965-hw.h +++ b/drivers/net/wireless/iwlwifi/iwl-4965-hw.h @@ -645,21 +645,43 @@ static inline int iwl4965_hw_valid_rtc_data_addr(u32 addr) (addr < KDR_RTC_DATA_UPPER_BOUND); } -/********************* START TXPOWER *****************************************/ - -enum { - CALIB_CH_GROUP_1 = 0, - CALIB_CH_GROUP_2 = 1, - CALIB_CH_GROUP_3 = 2, - CALIB_CH_GROUP_4 = 3, - CALIB_CH_GROUP_5 = 4, - CALIB_CH_GROUP_MAX -}; +/********************* START TEMPERATURE *************************************/ -/* Temperature calibration offset is 3% 0C in Kelvin */ +/* + * 4965 temperature calculation. + * + * The driver must calculate the device temperature before calculating + * a txpower setting (amplifier gain is temperature dependent). The + * calculation uses 4 measurements, 3 of which (R1, R2, R3) are calibration + * values used for the life of the driver, and one of which (R4) is the + * real-time temperature indicator. + * + * uCode provides all 4 values to the driver via the "initialize alive" + * notification (see struct iwl4965_init_alive_resp). After the runtime uCode + * image loads, uCode updates the R4 value via statistics notifications + * (see STATISTICS_NOTIFICATION), which occur after each received beacon + * when associated, or can be requested via REPLY_STATISTICS_CMD. + * + * NOTE: uCode provides the R4 value as a 23-bit signed value. Driver + * must sign-extend to 32 bits before applying formula below. + * + * Formula: + * + * degrees Kelvin = ((97 * 259 * (R4 - R2) / (R3 - R1)) / 100) + 8 + * + * NOTE: The basic formula is 259 * (R4-R2) / (R3-R1). The 97/100 is + * an additional correction, which should be centered around 0 degrees + * Celsius (273 degrees Kelvin). The 8 (3 percent of 273) compensates for + * centering the 97/100 correction around 0 degrees K. + * + * Add 273 to Kelvin value to find degrees Celsius, for comparing current + * temperature with factory-measured temperatures when calculating txpower + * settings. + */ #define TEMPERATURE_CALIB_KELVIN_OFFSET 8 #define TEMPERATURE_CALIB_A_VAL 259 +/* Limit range of calculated temperature to be between these Kelvin values */ #define IWL_TX_POWER_TEMPERATURE_MIN (263) #define IWL_TX_POWER_TEMPERATURE_MAX (410) @@ -667,6 +689,19 @@ enum { (((t) < IWL_TX_POWER_TEMPERATURE_MIN) || \ ((t) > IWL_TX_POWER_TEMPERATURE_MAX)) +/********************* END TEMPERATURE ***************************************/ + +/********************* START TXPOWER *****************************************/ + +enum { + CALIB_CH_GROUP_1 = 0, + CALIB_CH_GROUP_2 = 1, + CALIB_CH_GROUP_3 = 2, + CALIB_CH_GROUP_4 = 3, + CALIB_CH_GROUP_5 = 4, + CALIB_CH_GROUP_MAX +}; + #define IWL_TX_POWER_MIMO_REGULATORY_COMPENSATION (6) #define IWL_TX_POWER_TARGET_POWER_MIN (0) /* 0 dBm = 1 milliwatt */ -- cgit v1.2.3