usb: mtu3: fix the issue about SetFeature(U1/U2_Enable)

Fix the issue: device doesn't accept LGO_U1/U2:
1. set SW_U1/U2_ACCEPT_ENABLE to eanble controller to accept LGO_U1/U2
    by default;
2. enable/disable controller to initiate requests for transition into
    U1/U2 by SW_U1/U2_REQUEST_ENABLE instead of SW_U1/U2_ACCEPT_ENABLE;
Signed-off-by: Chunfeng Yun <chunfeng.yun@mediatek.com>
Signed-off-by: Felipe Balbi <felipe.balbi@linux.intel.com>

drivers/usb/mtu3/mtu3_core.c

@@ -578,8 +578,10 @@ static void mtu3_regs_init(struct mtu3 *mtu)
 	if (mtu->is_u3_ip) {
 		/* disable LGO_U1/U2 by default */
 		mtu3_clrbits(mbase, U3D_LINK_POWER_CONTROL,
-				SW_U1_ACCEPT_ENABLE | SW_U2_ACCEPT_ENABLE |
 				SW_U1_REQUEST_ENABLE | SW_U2_REQUEST_ENABLE);
+		/* enable accept LGO_U1/U2 link command from host */
+		mtu3_setbits(mbase, U3D_LINK_POWER_CONTROL,
+				SW_U1_ACCEPT_ENABLE | SW_U2_ACCEPT_ENABLE);
 		/* device responses to u3_exit from host automatically */
 		mtu3_clrbits(mbase, U3D_LTSSM_CTRL, SOFT_U3_EXIT_EN);
 		/* automatically build U2 link when U3 detect fail */

drivers/usb/mtu3/mtu3_gadget_ep0.c

@@ -336,9 +336,9 @@ static int ep0_handle_feature_dev(struct mtu3 *mtu,
 
 		lpc = mtu3_readl(mbase, U3D_LINK_POWER_CONTROL);
 		if (set)
-			lpc |= SW_U1_ACCEPT_ENABLE;
+			lpc |= SW_U1_REQUEST_ENABLE;
 		else
-			lpc &= ~SW_U1_ACCEPT_ENABLE;
+			lpc &= ~SW_U1_REQUEST_ENABLE;
 		mtu3_writel(mbase, U3D_LINK_POWER_CONTROL, lpc);
 
 		mtu->u1_enable = !!set;
@@ -351,9 +351,9 @@ static int ep0_handle_feature_dev(struct mtu3 *mtu,
 
 		lpc = mtu3_readl(mbase, U3D_LINK_POWER_CONTROL);
 		if (set)
-			lpc |= SW_U2_ACCEPT_ENABLE;
+			lpc |= SW_U2_REQUEST_ENABLE;
 		else
-			lpc &= ~SW_U2_ACCEPT_ENABLE;
+			lpc &= ~SW_U2_REQUEST_ENABLE;
 		mtu3_writel(mbase, U3D_LINK_POWER_CONTROL, lpc);
 
 		mtu->u2_enable = !!set;