iwlegacy: fix tx_power initialization

priv->tx_power_next is not initialized to max supported power,
but instead default value is used, what cause errors like

[ 58.597834] iwl3945 0000:03:00.0: Requested user TXPOWER 15 above upper limit 14.
[ 58.597839] iwl3945 0000:03:00.0: Error setting Tx power (-22).

if maximum tx power read from the eeprom is smaller than default.
In consequence card is unable to initialize properly. Fix the problem
and cleanup tx power initialization.

Reported-and-tested-by: Robin Dong <[e-mail]>
Signed-off-by: Stanislaw Gruszka <[e-mail]>
Signed-off-by: John W. Linville <[e-mail]>

drivers/net/wireless/iwlegacy/iwl-3945-hw.h

···
 /* RSSI to dBm */
 #define IWL39_RSSI_OFFSET	95
 
-#define IWL_DEFAULT_TX_POWER	0x0F
-
 /*
  * EEPROM related constants, enums, and structures.
  */

drivers/net/wireless/iwlegacy/iwl-4965-hw.h

···
 
 #define IWL4965_DEFAULT_TX_RETRY  15
 
-/* Limit range of txpower output target to be between these values */
-#define IWL4965_TX_POWER_TARGET_POWER_MIN	(0)	/* 0 dBm: 1 milliwatt */
-
 /* EEPROM */
 #define IWL4965_FIRST_AMPDU_QUEUE	10
 

drivers/net/wireless/iwlegacy/iwl-core.c

···
 	struct ieee80211_channel *geo_ch;
 	struct ieee80211_rate *rates;
 	int i = 0;
+	s8 max_tx_power = 0;
 
 	if (priv->bands[IEEE80211_BAND_2GHZ].n_bitrates ||
 	    priv->bands[IEEE80211_BAND_5GHZ].n_bitrates) {
···
 
 			geo_ch->flags |= ch->ht40_extension_channel;
 
-			if (ch->max_power_avg > priv->tx_power_device_lmt)
-				priv->tx_power_device_lmt = ch->max_power_avg;
+			if (ch->max_power_avg > max_tx_power)
+				max_tx_power = ch->max_power_avg;
 		} else {
 			geo_ch->flags |= IEEE80211_CHAN_DISABLED;
 		}
···
 				"restricted" : "valid",
 				 geo_ch->flags);
 	}
+
+	priv->tx_power_device_lmt = max_tx_power;
+	priv->tx_power_user_lmt = max_tx_power;
+	priv->tx_power_next = max_tx_power;
 
 	if ((priv->bands[IEEE80211_BAND_5GHZ].n_channels == 0) &&
 	     priv->cfg->sku & IWL_SKU_A) {
···
 	if (!priv->cfg->ops->lib->send_tx_power)
 		return -EOPNOTSUPP;
 
-	if (tx_power < IWL4965_TX_POWER_TARGET_POWER_MIN) {
+	/* 0 dBm mean 1 milliwatt */
+	if (tx_power < 0) {
 		IWL_WARN(priv,
-			 "Requested user TXPOWER %d below lower limit %d.\n",
-			 tx_power,
-			 IWL4965_TX_POWER_TARGET_POWER_MIN);
+			 "Requested user TXPOWER %d below 1 mW.\n",
+			 tx_power);
 		return -EINVAL;
 	}
 

drivers/net/wireless/iwlegacy/iwl-eeprom.c

···
 					     flags & EEPROM_CHANNEL_RADAR))
 				       ? "" : "not ");
 
-			/* Set the tx_power_user_lmt to the highest power
-			 * supported by any channel */
-			if (eeprom_ch_info[ch].max_power_avg >
-						priv->tx_power_user_lmt)
-				priv->tx_power_user_lmt =
-				    eeprom_ch_info[ch].max_power_avg;
-
 			ch_info++;
 		}
 	}

drivers/net/wireless/iwlegacy/iwl3945-base.c

···
 	priv->force_reset[IWL_FW_RESET].reset_duration =
 		IWL_DELAY_NEXT_FORCE_FW_RELOAD;
 
-
-	priv->tx_power_user_lmt = IWL_DEFAULT_TX_POWER;
-	priv->tx_power_next = IWL_DEFAULT_TX_POWER;
-
 	if (eeprom->version < EEPROM_3945_EEPROM_VERSION) {
 		IWL_WARN(priv, "Unsupported EEPROM version: 0x%04X\n",
 			 eeprom->version);

drivers/net/wireless/iwlegacy/iwl4965-base.c

···
 
 	iwl_legacy_init_scan_params(priv);
 
-	/* Set the tx_power_user_lmt to the lowest power level
-	 * this value will get overwritten by channel max power avg
-	 * from eeprom */
-	priv->tx_power_user_lmt = IWL4965_TX_POWER_TARGET_POWER_MIN;
-	priv->tx_power_next = IWL4965_TX_POWER_TARGET_POWER_MIN;
-
 	ret = iwl_legacy_init_channel_map(priv);
 	if (ret) {
 		IWL_ERR(priv, "initializing regulatory failed: %d\n", ret);