rtlwifi: rtl8723be: Add antenna select module parameter

A number of new laptops have been delivered with only a single antenna.
In principle, this is OK; however, a problem arises when the on-board
EEPROM is programmed to use the other antenna connection. The option
of opening the computer and moving the connector is not always possible
as it will void the warranty in some cases. In addition, this solution
breaks the Windows driver when the box dual boots Linux and Windows.

A fix involving a new module parameter has been developed.  This commit
adds the new parameter and implements the changes needed for the driver.

Signed-off-by: Larry Finger <Larry.Finger@lwfinger.net>
Cc: Stable <stable@vger.kernel.org> [V4.0+]
Signed-off-by: Kalle Valo <kvalo@codeaurora.org>

drivers/net/wireless/realtek/rtlwifi/rtl8723be/hw.c

@@ -2684,6 +2684,7 @@ void rtl8723be_read_bt_coexist_info_from_hwpg(struct ieee80211_hw *hw,
 					      bool auto_load_fail, u8 *hwinfo)
 {
 	struct rtl_priv *rtlpriv = rtl_priv(hw);
+	struct rtl_mod_params *mod_params = rtlpriv->cfg->mod_params;
 	u8 value;
 	u32 tmpu_32;
 
@@ -2702,6 +2703,10 @@ void rtl8723be_read_bt_coexist_info_from_hwpg(struct ieee80211_hw *hw,
 		rtlpriv->btcoexist.btc_info.ant_num = ANT_X2;
 	}
 
+	/* override ant_num / ant_path */
+	if (mod_params->ant_sel)
+		rtlpriv->btcoexist.btc_info.ant_num =
+			(mod_params->ant_sel == 1 ? ANT_X2 : ANT_X1);
 }
 
 void rtl8723be_bt_reg_init(struct ieee80211_hw *hw)

drivers/net/wireless/realtek/rtlwifi/rtl8723be/sw.c

@@ -273,6 +273,7 @@ static struct rtl_mod_params rtl8723be_mod_params = {
 	.msi_support = false,
 	.disable_watchdog = false,
 	.debug = DBG_EMERG,
+	.ant_sel = 0,
 };
 
 static struct rtl_hal_cfg rtl8723be_hal_cfg = {
@@ -394,6 +395,7 @@ module_param_named(fwlps, rtl8723be_mod_params.fwctrl_lps, bool, 0444);
 module_param_named(msi, rtl8723be_mod_params.msi_support, bool, 0444);
 module_param_named(disable_watchdog, rtl8723be_mod_params.disable_watchdog,
 		   bool, 0444);
+module_param_named(ant_sel, rtl8723be_mod_params.ant_sel, int, 0444);
 MODULE_PARM_DESC(swenc, "Set to 1 for software crypto (default 0)\n");
 MODULE_PARM_DESC(ips, "Set to 0 to not use link power save (default 1)\n");
 MODULE_PARM_DESC(swlps, "Set to 1 to use SW control power save (default 0)\n");
@@ -402,6 +404,7 @@ MODULE_PARM_DESC(msi, "Set to 1 to use MSI interrupts mode (default 0)\n");
 MODULE_PARM_DESC(debug, "Set debug level (0-5) (default 0)");
 MODULE_PARM_DESC(disable_watchdog,
 		 "Set to 1 to disable the watchdog (default 0)\n");
+MODULE_PARM_DESC(ant_sel, "Set to 1 or 2 to force antenna number (default 0)\n");
 
 static SIMPLE_DEV_PM_OPS(rtlwifi_pm_ops, rtl_pci_suspend, rtl_pci_resume);
 

drivers/net/wireless/realtek/rtlwifi/wifi.h

@@ -2246,6 +2246,9 @@ struct rtl_mod_params {
 
 	/* default 0: 1 means do not disable interrupts */
 	bool int_clear;
+
+	/* select antenna */
+	int ant_sel;
 };
 
 struct rtl_hal_usbint_cfg {