[PATCH v4 4/5] usb: dwc3: Add quirk for Synopsis device disconnection errata

[Sneeker Yeh <sneeker.yeh@gmail.com>]

Synopsis Designware USB3 IP earlier than v3.00a which is configured in silicon
with DWC_USB3_SUSPEND_ON_DISCONNECT_EN=1, would need a specific quirk to prevent
xhci host controller from dying when device is disconnected.

Since DWC_USB3_SUSPEND_ON_DISCONNECT_EN is an IP configuration whose state
cannot be checked from software in runtime, it has to be enabled via platform
data or device tree.

Signed-off-by: Sneeker Yeh <Sneeker.Yeh@tw.fujitsu.com>
---
 Documentation/devicetree/bindings/usb/dwc3.txt |   17 +++++++++++++++++
 drivers/usb/dwc3/core.c                        |    6 ++++++
 drivers/usb/dwc3/core.h                        |    4 ++++
 drivers/usb/dwc3/host.c                        |    4 ++++
 drivers/usb/dwc3/platform_data.h               |    8 ++++++++
 5 files changed, 39 insertions(+)

diff --git a/Documentation/devicetree/bindings/usb/dwc3.txt b/Documentation/devicetree/bindings/usb/dwc3.txt
index cd7f045..1b78b29 100644
--- a/Documentation/devicetree/bindings/usb/dwc3.txt
+++ b/Documentation/devicetree/bindings/usb/dwc3.txt
@@ -37,6 +37,23 @@ Optional properties:
  - 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
+ - snps,has_suspend_on_disconnect: true when IP is configured in silicon with
+			DWC_USB3_SUSPEND_ON_DISCONNECT_EN=1, it can inject a
+			specific quirk to prevent xhci host controller from
+			dying when usb device is disconnected from root hub.
+			Since DWC_USB3_SUSPEND_ON_DISCONNECT_EN is an IP
+			configuration whose state cannot be checked from
+			software in runtime, it has to be enabled via platform
+			data or device tree.
+
+			xhci host dying symptom here is caused by that
+			DWC_USB3_SUSPEND_ON_DISCONNECT_EN=1
+			configuration makes IP auto-suspended after PORTCSC is
+			cleared when usb device detached, then an asynchronous
+			disconnection procedure might fail using endpoint
+			command that suspened IP won't have any response to.
+
+			this issue is fixed when IP version >= 3.00a.
 
 This is usually a subnode to DWC3 glue to which it is connected.
 
diff --git a/drivers/usb/dwc3/core.c b/drivers/usb/dwc3/core.c
index 9f0e209..705980c 100644
--- a/drivers/usb/dwc3/core.c
+++ b/drivers/usb/dwc3/core.c
@@ -838,6 +838,9 @@ static int dwc3_probe(struct platform_device *pdev)
 				"snps,tx_de_emphasis_quirk");
 		of_property_read_u8(node, "snps,tx_de_emphasis",
 				&tx_de_emphasis);
+
+		dwc->suspend_on_disconnect_quirk = of_property_read_bool(node,
+				"snps,has_suspend_on_disconnect");
 	} else if (pdata) {
 		dwc->maximum_speed = pdata->maximum_speed;
 		dwc->has_lpm_erratum = pdata->has_lpm_erratum;
@@ -864,6 +867,9 @@ static int dwc3_probe(struct platform_device *pdev)
 		dwc->tx_de_emphasis_quirk = pdata->tx_de_emphasis_quirk;
 		if (pdata->tx_de_emphasis)
 			tx_de_emphasis = pdata->tx_de_emphasis;
+
+		dwc->suspend_on_disconnect_quirk =
+			pdata->has_suspend_on_disconnect;
 	}
 
 	/* default to superspeed if no maximum_speed passed */
diff --git a/drivers/usb/dwc3/core.h b/drivers/usb/dwc3/core.h
index 0b3bb0f..dfc7d63 100644
--- a/drivers/usb/dwc3/core.h
+++ b/drivers/usb/dwc3/core.h
@@ -688,6 +688,9 @@ struct dwc3_scratchpad_array {
  * @resize_fifos: tells us it's ok to reconfigure our TxFIFO sizes.
  * @setup_packet_pending: true when there's a Setup Packet in FIFO. Workaround
  * @start_config_issued: true when StartConfig command has been issued
+ * @suspend_on_disconnect_quirk: set if core was configured with
+ *			DWC_USB3_SUSPEND_ON_DISCONNECT_EN=1. Note that there's
+ *			now way for software to detect this in runtime.
  * @three_stage_setup: set if we perform a three phase setup
  * @disable_scramble_quirk: set if we enable the disable scramble quirk
  * @u2exit_lfps_quirk: set if we enable u2exit lfps quirk
@@ -813,6 +816,7 @@ struct dwc3 {
 	unsigned		resize_fifos:1;
 	unsigned		setup_packet_pending:1;
 	unsigned		start_config_issued:1;
+	unsigned		suspend_on_disconnect_quirk:1;
 	unsigned		three_stage_setup:1;
 
 	unsigned		disable_scramble_quirk:1;
diff --git a/drivers/usb/dwc3/host.c b/drivers/usb/dwc3/host.c
index 12bfd3c..9c42074 100644
--- a/drivers/usb/dwc3/host.c
+++ b/drivers/usb/dwc3/host.c
@@ -53,6 +53,10 @@ int dwc3_host_init(struct dwc3 *dwc)
 	pdata.usb3_lpm_capable = 1;
 #endif
 
+	if ((dwc->revision < DWC3_REVISION_300A) &&
+	    dwc->suspend_on_disconnect_quirk)
+		pdata.delay_portcsc_clear = 1;
+
 	ret = platform_device_add_data(xhci, &pdata, sizeof(pdata));
 	if (ret) {
 		dev_err(dwc->dev, "couldn't add platform data to xHCI device\n");
diff --git a/drivers/usb/dwc3/platform_data.h b/drivers/usb/dwc3/platform_data.h
index a3a3b6d..ebc8eb4 100644
--- a/drivers/usb/dwc3/platform_data.h
+++ b/drivers/usb/dwc3/platform_data.h
@@ -20,6 +20,13 @@
 #include <linux/usb/ch9.h>
 #include <linux/usb/otg.h>
 
+/**
+ * struct dwc3_platform_data - platform data of dwc3 controller
+ * @has_suspend_on_disconnect: true if core was configured with
+ *			DWC_USB3_SUSPEND_ON_DISCONNECT_EN=1. Note that there's
+ *			now way for software to detect this in runtime.
+ */
+
 struct dwc3_platform_data {
 	enum usb_device_speed maximum_speed;
 	enum usb_dr_mode dr_mode;
@@ -32,6 +39,7 @@ struct dwc3_platform_data {
 
 	unsigned disable_scramble_quirk:1;
 	unsigned has_lpm_erratum:1;
+	unsigned has_suspend_on_disconnect:1;
 	unsigned u2exit_lfps_quirk:1;
 	unsigned u2ss_inp3_quirk:1;
 	unsigned req_p1p2p3_quirk:1;
-- 
1.7.9.5