[PATCH 4.2 006/110] rtlwifi: rtl8821ae: Fix system lockups on boot

[Greg Kroah-Hartman <gregkh@linuxfoundation.org>]

4.2-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Larry Finger <Larry.Finger@lwfinger.net>

commit 54328e64047a54b8fc2362c2e1f0fa16c90f739f upstream.

In commit 1277fa2ab2f9 ("rtlwifi: Remove the clear interrupt routine from all
drivers"), the code that cleared all interrupt enable bits before setting them
was removed for all PCI drivers. This fixed an issue that caused TX to be
blocked for 3-5 seconds. On some RTL8821AE units, this change causes soft
lockups to occur on boot. For that reason, the portion of the earlier commit
that applied to rtl8821ae is reverted. Kernels 4.1 and newer are affected.

See http://marc.info/?l=linux-wireless&m=144373370103285&w=2 and
https://bugzilla.opensuse.org/show_bug.cgi?id=944978 for two cases where
this regression affected user systems. Note that this bug does not appear on
any of the developer's setups. For those users whose systems are affected
by the TX blockage, but do not lock up on boot, a module parameter is added
to disable the interrupt clear

Fixes: 1277fa2ab2f9 ("rtlwifi: Remove the clear interrupt routine from all drivers")
Signed-off-by: Larry Finger <Larry.Finger@lwfinger.net>
Signed-off-by: Kalle Valo <kvalo@codeaurora.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

---
 drivers/net/wireless/rtlwifi/pci.h          |    2 ++
 drivers/net/wireless/rtlwifi/rtl8821ae/hw.c |   17 +++++++++++++++++
 drivers/net/wireless/rtlwifi/rtl8821ae/sw.c |    5 +++++
 drivers/net/wireless/rtlwifi/wifi.h         |    3 +++
 4 files changed, 27 insertions(+)

--- a/drivers/net/wireless/rtlwifi/pci.h
+++ b/drivers/net/wireless/rtlwifi/pci.h
@@ -247,6 +247,8 @@ struct rtl_pci {
 	/* MSI support */
 	bool msi_support;
 	bool using_msi;
+	/* interrupt clear before set */
+	bool int_clear;
 };
 
 struct mp_adapter {
--- a/drivers/net/wireless/rtlwifi/rtl8821ae/hw.c
+++ b/drivers/net/wireless/rtlwifi/rtl8821ae/hw.c
@@ -2253,11 +2253,28 @@ void rtl8821ae_set_qos(struct ieee80211_
 	}
 }
 
+static void rtl8821ae_clear_interrupt(struct ieee80211_hw *hw)
+{
+	struct rtl_priv *rtlpriv = rtl_priv(hw);
+	u32 tmp = rtl_read_dword(rtlpriv, REG_HISR);
+
+	rtl_write_dword(rtlpriv, REG_HISR, tmp);
+
+	tmp = rtl_read_dword(rtlpriv, REG_HISRE);
+	rtl_write_dword(rtlpriv, REG_HISRE, tmp);
+
+	tmp = rtl_read_dword(rtlpriv, REG_HSISR);
+	rtl_write_dword(rtlpriv, REG_HSISR, tmp);
+}
+
 void rtl8821ae_enable_interrupt(struct ieee80211_hw *hw)
 {
 	struct rtl_priv *rtlpriv = rtl_priv(hw);
 	struct rtl_pci *rtlpci = rtl_pcidev(rtl_pcipriv(hw));
 
+	if (!rtlpci->int_clear)
+		rtl8821ae_clear_interrupt(hw);/*clear it here first*/
+
 	rtl_write_dword(rtlpriv, REG_HIMR, rtlpci->irq_mask[0] & 0xFFFFFFFF);
 	rtl_write_dword(rtlpriv, REG_HIMRE, rtlpci->irq_mask[1] & 0xFFFFFFFF);
 	rtlpci->irq_enabled = true;
--- a/drivers/net/wireless/rtlwifi/rtl8821ae/sw.c
+++ b/drivers/net/wireless/rtlwifi/rtl8821ae/sw.c
@@ -96,6 +96,7 @@ int rtl8821ae_init_sw_vars(struct ieee80
 
 	rtl8821ae_bt_reg_init(hw);
 	rtlpci->msi_support = rtlpriv->cfg->mod_params->msi_support;
+	rtlpci->int_clear = rtlpriv->cfg->mod_params->int_clear;
 	rtlpriv->btcoexist.btc_ops = rtl_btc_get_ops_pointer();
 
 	rtlpriv->dm.dm_initialgain_enable = 1;
@@ -167,6 +168,7 @@ int rtl8821ae_init_sw_vars(struct ieee80
 	rtlpriv->psc.swctrl_lps = rtlpriv->cfg->mod_params->swctrl_lps;
 	rtlpriv->psc.fwctrl_lps = rtlpriv->cfg->mod_params->fwctrl_lps;
 	rtlpci->msi_support = rtlpriv->cfg->mod_params->msi_support;
+	rtlpci->msi_support = rtlpriv->cfg->mod_params->int_clear;
 	if (rtlpriv->cfg->mod_params->disable_watchdog)
 		pr_info("watchdog disabled\n");
 	rtlpriv->psc.reg_fwctrl_lps = 3;
@@ -308,6 +310,7 @@ static struct rtl_mod_params rtl8821ae_m
 	.swctrl_lps = false,
 	.fwctrl_lps = true,
 	.msi_support = true,
+	.int_clear = true,
 	.debug = DBG_EMERG,
 	.disable_watchdog = 0,
 };
@@ -437,6 +440,7 @@ module_param_named(fwlps, rtl8821ae_mod_
 module_param_named(msi, rtl8821ae_mod_params.msi_support, bool, 0444);
 module_param_named(disable_watchdog, rtl8821ae_mod_params.disable_watchdog,
 		   bool, 0444);
+module_param_named(int_clear, rtl8821ae_mod_params.int_clear, bool, 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");
@@ -444,6 +448,7 @@ MODULE_PARM_DESC(fwlps, "Set to 1 to use
 MODULE_PARM_DESC(msi, "Set to 1 to use MSI interrupts mode (default 1)\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(int_clear, "Set to 1 to disable interrupt clear before set (default 0)\n");
 
 static SIMPLE_DEV_PM_OPS(rtlwifi_pm_ops, rtl_pci_suspend, rtl_pci_resume);
 
--- a/drivers/net/wireless/rtlwifi/wifi.h
+++ b/drivers/net/wireless/rtlwifi/wifi.h
@@ -2234,6 +2234,9 @@ struct rtl_mod_params {
 
 	/* default 0: 1 means disable */
 	bool disable_watchdog;
+
+	/* default 0: 1 means do not disable interrupts */
+	bool int_clear;
 };
 
 struct rtl_hal_usbint_cfg {