usb: dwc3: add a quirk xhci_slow_suspend_quirk

On some xHCI controllers (e.g. Rockchip SoCs), which are
integrated in DWC3 IP, need an extraordinary delay to wait
for xHCI enter the Halted state(i.e. HCH in the USBSTS
register is '1'), especially if DWC3 is in DRD mode.

Change-Id: I67c84d4768df95f7616d6716a77cf743e4334122
Signed-off-by: Wu Liang feng <wulf@rock-chips.com>

Documentation/devicetree/bindings/usb/dwc3.txt

@@ -70,6 +70,9 @@ Optional properties:
 			during HS transmit.
  - snps,dis_metastability_quirk: when set, disable metastability workaround.
 			CAUTION: use only if you are absolutely sure of it.
+ - snps,xhci-slow-suspend-quirk: when set, need an extraordinary delay to wait
+			for xHC enter the Halted state (i.e. HCH in the USBSTS
+			register is '1').
  - snps,is-utmi-l1-suspend: true when DWC3 asserts output signal
 			utmi_l1_suspend_n, false when asserts utmi_sleep_n
  - snps,hird-threshold: HIRD threshold

drivers/usb/dwc3/core.c

@@ -1285,6 +1285,8 @@ static void dwc3_get_properties(struct dwc3 *dwc)
 				"snps,dis-del-phy-power-chg-quirk");
 	dwc->dis_tx_ipgap_linecheck_quirk = device_property_read_bool(dev,
 				"snps,dis-tx-ipgap-linecheck-quirk");
+	dwc->xhci_slow_suspend_quirk = device_property_read_bool(dev,
+				"snps,xhci-slow-suspend-quirk");
 
 	dwc->tx_de_emphasis_quirk = device_property_read_bool(dev,
 				"snps,tx_de_emphasis_quirk");

drivers/usb/dwc3/core.h

@@ -991,6 +991,9 @@ struct dwc3_scratchpad_array {
  *			change quirk.
  * @dis_tx_ipgap_linecheck_quirk: set if we disable u2mac linestate
  *			check during HS transmit.
+ * @xhci_slow_suspend_quirk: set if need an extraordinary delay to wait
+ *			for xHC enter the Halted state after the Run/Stop
+ *			(R/S) bit is cleared to '0'.
  * @tx_de_emphasis_quirk: set if we enable Tx de-emphasis quirk
  * @tx_de_emphasis: Tx de-emphasis value
  * 	0	- -6dB de-emphasis
@@ -1162,6 +1165,7 @@ struct dwc3 {
 	unsigned		dis_u2_freeclk_exists_quirk:1;
 	unsigned		dis_del_phy_power_chg_quirk:1;
 	unsigned		dis_tx_ipgap_linecheck_quirk:1;
+	unsigned		xhci_slow_suspend_quirk:1;
 
 	unsigned		tx_de_emphasis_quirk:1;
 	unsigned		tx_de_emphasis:2;

drivers/usb/dwc3/host.c

@@ -93,6 +93,9 @@ int dwc3_host_init(struct dwc3 *dwc)
 	if (dwc->usb3_lpm_capable)
 		props[prop_idx++].name = "usb3-lpm-capable";
 
+	if (dwc->xhci_slow_suspend_quirk)
+		props[prop_idx++].name = "xhci-slow-suspend";
+
 	/**
 	 * WORKAROUND: dwc3 revisions <=3.00a have a limitation
 	 * where Port Disable command doesn't work.