[PATCH 3/3] usb: dwc3: qcom: pass live SS-link state into PHY at suspend entry

[Tapas Rana <tapas.rana@oss.qualcomm.com>]

dwc3_qcom_suspend() puts each host port into autonomous/wake mode
without ever telling the PHY whether a SuperSpeed device is currently
attached. qmp_combo_enable_autonomous_mode(), made SS-aware in the
previous patch, therefore has no live signal to act on and always
sees QCOM_USB_SS_UNKNOWN, falling back to the legacy receiver-detect
mask regardless of actual link state.

Add dwc3_qcom_read_ss_state() to check each port's USB3 roothub for
an attached child device running at SuperSpeed or above, and pass the
result as the submode argument of phy_set_mode_ext() so the PHY can
select LFPS detection when appropriate.

Signed-off-by: Tapas Rana <tapas.rana@oss.qualcomm.com>
---
 drivers/usb/dwc3/dwc3-qcom.c | 36 +++++++++++++++++++++++++++++++++++-
 1 file changed, 35 insertions(+), 1 deletion(-)

diff --git a/drivers/usb/dwc3/dwc3-qcom.c b/drivers/usb/dwc3/dwc3-qcom.c
index ac68b4218b56..d4ba095e47eb 100644
--- a/drivers/usb/dwc3/dwc3-qcom.c
+++ b/drivers/usb/dwc3/dwc3-qcom.c
@@ -19,6 +19,7 @@
 #include <linux/iopoll.h>
 #include <linux/usb/hcd.h>
 #include <linux/usb.h>
+#include <linux/phy/phy-qcom-qmp-usb-ss.h>
 #include "core.h"
 #include "glue.h"
 
@@ -66,6 +67,7 @@ struct dwc3_qcom_port {
 	int			dm_hs_phy_irq;
 	int			ss_phy_irq;
 	enum usb_device_speed	usb2_speed;
+	enum qcom_usb_ss_state  ss_state;
 };
 
 struct dwc3_qcom {
@@ -251,6 +253,34 @@ static enum usb_device_speed dwc3_qcom_read_usb2_speed(struct dwc3_qcom *qcom, i
 	return udev->speed;
 }
 
+static enum qcom_usb_ss_state dwc3_qcom_read_ss_state(struct dwc3_qcom *qcom, int port_index)
+{
+	struct usb_device *udev;
+	struct usb_hcd __maybe_unused *hcd, *usb3_hcd;
+	struct dwc3 *dwc = &qcom->dwc;
+
+	/*
+	 * FIXME: Fix this layering violation.
+	 */
+	hcd = platform_get_drvdata(dwc->xhci);
+	if (!hcd)
+		return QCOM_USB_SS_ABSENT;
+
+#ifdef CONFIG_USB
+	usb3_hcd = hcd->shared_hcd ? hcd->shared_hcd : hcd;
+	if (!usb3_hcd->self.root_hub)
+		return QCOM_USB_SS_ABSENT;
+
+	udev = usb_hub_find_child(usb3_hcd->self.root_hub, port_index + 1);
+#else
+	udev = NULL;
+#endif
+	if (!udev)
+		return QCOM_USB_SS_ABSENT;
+
+	return udev->speed >= USB_SPEED_SUPER ? QCOM_USB_SS_PRESENT : QCOM_USB_SS_ABSENT;
+}
+
 static void dwc3_qcom_enable_wakeup_irq(int irq, unsigned int polarity)
 {
 	if (!irq)
@@ -359,8 +389,12 @@ static int dwc3_qcom_suspend(struct dwc3_qcom *qcom, bool wakeup)
 	 * freezable workqueue.
 	 */
 	if (dwc3_qcom_is_host(qcom) && wakeup) {
-		for (i = 0; i < qcom->num_ports; i++)
+		for (i = 0; i < qcom->num_ports; i++) {
 			qcom->ports[i].usb2_speed = dwc3_qcom_read_usb2_speed(qcom, i);
+			qcom->ports[i].ss_state = dwc3_qcom_read_ss_state(qcom, i);
+			phy_set_mode_ext(qcom->dwc.usb3_generic_phy[i], PHY_MODE_USB_HOST,
+					 qcom->ports[i].ss_state);
+		}
 		dwc3_qcom_enable_interrupts(qcom);
 	}
 
-- 
2.43.0