rtlwifi: rtl8192ee: Fix DMA stalls

There are instances where the DMA engine stalls. The new code detects
such stalls and restarts DMA without needing a power reset.
Signed-off-by: Troy Tan <troy_tan@realsil.com.cn>
Signed-off-by: Larry Finger <Larry.Finger@lwfinger.net>
Cc: Stable <stable@vger.kernel.org> [3.18]
Signed-off-by: Kalle Valo <kvalo@codeaurora.org>

drivers/net/wireless/rtlwifi/rtl8192ee/hw.c

@@ -1137,6 +1137,139 @@ void rtl92ee_enable_hw_security_config(struct ieee80211_hw *hw)
 	rtlpriv->cfg->ops->set_hw_reg(hw, HW_VAR_WPA_CONFIG, &sec_reg_value);
 }
 
+static bool _rtl8192ee_check_pcie_dma_hang(struct rtl_priv *rtlpriv)
+{
+	u8 tmp;
+
+	/* write reg 0x350 Bit[26]=1. Enable debug port. */
+	tmp = rtl_read_byte(rtlpriv, REG_BACKDOOR_DBI_DATA + 3);
+	if (!(tmp & BIT(2))) {
+		rtl_write_byte(rtlpriv, REG_BACKDOOR_DBI_DATA + 3,
+			       tmp | BIT(2));
+		mdelay(100); /* Suggested by DD Justin_tsai. */
+	}
+
+	/* read reg 0x350 Bit[25] if 1 : RX hang
+	 * read reg 0x350 Bit[24] if 1 : TX hang
+	 */
+	tmp = rtl_read_byte(rtlpriv, REG_BACKDOOR_DBI_DATA + 3);
+	if ((tmp & BIT(0)) || (tmp & BIT(1))) {
+		RT_TRACE(rtlpriv, COMP_INIT, DBG_LOUD,
+			 "CheckPcieDMAHang8192EE(): true!!\n");
+		return true;
+	}
+	return false;
+}
+
+static void _rtl8192ee_reset_pcie_interface_dma(struct rtl_priv *rtlpriv,
+						bool mac_power_on)
+{
+	u8 tmp;
+	bool release_mac_rx_pause;
+	u8 backup_pcie_dma_pause;
+
+	RT_TRACE(rtlpriv, COMP_INIT, DBG_LOUD,
+		 "ResetPcieInterfaceDMA8192EE()\n");
+
+	/* Revise Note: Follow the document "PCIe RX DMA Hang Reset Flow_v03"
+	 * released by SD1 Alan.
+	 */
+
+	/* 1. disable register write lock
+	 *	write 0x1C bit[1:0] = 2'h0
+	 *	write 0xCC bit[2] = 1'b1
+	 */
+	tmp = rtl_read_byte(rtlpriv, REG_RSV_CTRL);
+	tmp &= ~(BIT(1) | BIT(0));
+	rtl_write_byte(rtlpriv, REG_RSV_CTRL, tmp);
+	tmp = rtl_read_byte(rtlpriv, REG_PMC_DBG_CTRL2);
+	tmp |= BIT(2);
+	rtl_write_byte(rtlpriv, REG_PMC_DBG_CTRL2, tmp);
+
+	/* 2. Check and pause TRX DMA
+	 *	write 0x284 bit[18] = 1'b1
+	 *	write 0x301 = 0xFF
+	 */
+	tmp = rtl_read_byte(rtlpriv, REG_RXDMA_CONTROL);
+	if (tmp & BIT(2)) {
+		/* Already pause before the function for another reason. */
+		release_mac_rx_pause = false;
+	} else {
+		rtl_write_byte(rtlpriv, REG_RXDMA_CONTROL, (tmp | BIT(2)));
+		release_mac_rx_pause = true;
+	}
+
+	backup_pcie_dma_pause = rtl_read_byte(rtlpriv, REG_PCIE_CTRL_REG + 1);
+	if (backup_pcie_dma_pause != 0xFF)
+		rtl_write_byte(rtlpriv, REG_PCIE_CTRL_REG + 1, 0xFF);
+
+	if (mac_power_on) {
+		/* 3. reset TRX function
+		 *	write 0x100 = 0x00
+		 */
+		rtl_write_byte(rtlpriv, REG_CR, 0);
+	}
+
+	/* 4. Reset PCIe DMA
+	 *	write 0x003 bit[0] = 0
+	 */
+	tmp = rtl_read_byte(rtlpriv, REG_SYS_FUNC_EN + 1);
+	tmp &= ~(BIT(0));
+	rtl_write_byte(rtlpriv, REG_SYS_FUNC_EN + 1, tmp);
+
+	/* 5. Enable PCIe DMA
+	 *	write 0x003 bit[0] = 1
+	 */
+	tmp = rtl_read_byte(rtlpriv, REG_SYS_FUNC_EN + 1);
+	tmp |= BIT(0);
+	rtl_write_byte(rtlpriv, REG_SYS_FUNC_EN + 1, tmp);
+
+	if (mac_power_on) {
+		/* 6. enable TRX function
+		 *	write 0x100 = 0xFF
+		 */
+		rtl_write_byte(rtlpriv, REG_CR, 0xFF);
+
+		/* We should init LLT & RQPN and
+		 * prepare Tx/Rx descrptor address later
+		 * because MAC function is reset.
+		 */
+	}
+
+	/* 7. Restore PCIe autoload down bit
+	 *	write 0xF8 bit[17] = 1'b1
+	 */
+	tmp = rtl_read_byte(rtlpriv, REG_MAC_PHY_CTRL_NORMAL + 2);
+	tmp |= BIT(1);
+	rtl_write_byte(rtlpriv, REG_MAC_PHY_CTRL_NORMAL + 2, tmp);
+
+	/* In MAC power on state, BB and RF maybe in ON state,
+	 * if we release TRx DMA here
+	 * it will cause packets to be started to Tx/Rx,
+	 * so we release Tx/Rx DMA later.
+	 */
+	if (!mac_power_on) {
+		/* 8. release TRX DMA
+		 *	write 0x284 bit[18] = 1'b0
+		 *	write 0x301 = 0x00
+		 */
+		if (release_mac_rx_pause) {
+			tmp = rtl_read_byte(rtlpriv, REG_RXDMA_CONTROL);
+			rtl_write_byte(rtlpriv, REG_RXDMA_CONTROL,
+				       (tmp & (~BIT(2))));
+		}
+		rtl_write_byte(rtlpriv, REG_PCIE_CTRL_REG + 1,
+			       backup_pcie_dma_pause);
+	}
+
+	/* 9. lock system register
+	 *	write 0xCC bit[2] = 1'b0
+	 */
+	tmp = rtl_read_byte(rtlpriv, REG_PMC_DBG_CTRL2);
+	tmp &= ~(BIT(2));
+	rtl_write_byte(rtlpriv, REG_PMC_DBG_CTRL2, tmp);
+}
+
 int rtl92ee_hw_init(struct ieee80211_hw *hw)
 {
 	struct rtl_priv *rtlpriv = rtl_priv(hw);
@@ -1162,6 +1295,13 @@ int rtl92ee_hw_init(struct ieee80211_hw *hw)
 		rtlhal->fw_ps_state = FW_PS_STATE_ALL_ON_92E;
 	}
 
+	if (_rtl8192ee_check_pcie_dma_hang(rtlpriv)) {
+		RT_TRACE(rtlpriv, COMP_INIT, DBG_DMESG, "92ee dma hang!\n");
+		_rtl8192ee_reset_pcie_interface_dma(rtlpriv,
+						    rtlhal->mac_func_enable);
+		rtlhal->mac_func_enable = false;
+	}
+
 	rtstatus = _rtl92ee_init_mac(hw);
 
 	rtl_write_byte(rtlpriv, 0x577, 0x03);

drivers/net/wireless/rtlwifi/rtl8192ee/reg.h

@@ -77,9 +77,11 @@
 #define REG_HIMRE				0x00B8
 #define REG_HISRE				0x00BC
 
+#define REG_PMC_DBG_CTRL2			0x00CC
 #define REG_EFUSE_ACCESS			0x00CF
 #define REG_HPON_FSM				0x00EC
 #define REG_SYS_CFG1				0x00F0
+#define REG_MAC_PHY_CTRL_NORMAL			0x00F8
 #define REG_SYS_CFG2				0x00FC
 
 #define REG_CR					0x0100