linux-kernel - [PATCH v3 3/4] usb: hcd: Caibrate PHY post hcd reset

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Date:	Mon, 14 Jul 2014 18:19:57 +0530
From:	Vivek Gautam <gautam.vivek@...sung.com>
To:	linux-usb@...r.kernel.org, linux-samsung-soc@...r.kernel.org
Cc:	linux-arm-kernel@...ts.infradead.org, linux-kernel@...r.kernel.org,
	gregkh@...uxfoundation.org, kishon@...com, kgene.kim@...sung.com,
	mathias.nyman@...el.com, jwerner@...omium.org,
	sergei.shtylyov@...entembedded.com,
	heikki.krogerus@...ux.intel.com, pratyush.anand@...com,
	Vivek Gautam <gautam.vivek@...sung.com>
Subject: [PATCH v3 3/4] usb: hcd: Caibrate PHY post hcd reset

Some quirky PHYs may require to be calibrated post the
hcd initialization.
The USB 3.0 DRD PHY on Exynos5420/5800 systems, coming along
with Synopsys's DWC3 controller, is one such PHY which needs
to be calibrated post xhci's reset at initialization time and
at resume time, to get the controller work at SuperSpeed.
So facilitating the HCDs to calibrate the PHY.

Signed-off-by: Vivek Gautam <gautam.vivek@...sung.com>
---
 drivers/usb/core/hcd.c |   22 ++++++++++++++++++++++
 1 file changed, 22 insertions(+)

diff --git a/drivers/usb/core/hcd.c b/drivers/usb/core/hcd.c
index 2841149..a344b76 100644
--- a/drivers/usb/core/hcd.c
+++ b/drivers/usb/core/hcd.c
@@ -2206,6 +2206,7 @@ int hcd_bus_resume(struct usb_device *rhdev, pm_message_t msg)
 	struct usb_hcd	*hcd = container_of(rhdev->bus, struct usb_hcd, self);
 	int		status;
 	int		old_state = hcd->state;
+	int		ret;
 
 	dev_dbg(&rhdev->dev, "usb %sresume\n",
 			(PMSG_IS_AUTO(msg) ? "auto-" : ""));
@@ -2220,6 +2221,17 @@ int hcd_bus_resume(struct usb_device *rhdev, pm_message_t msg)
 
 	hcd->state = HC_STATE_RESUMING;
 	status = hcd->driver->bus_resume(hcd);
+
+	/* calibrate the phy here */
+	if (!IS_ERR(hcd->gen_phy)) {
+		ret = phy_calibrate(hcd->gen_phy);
+		if (ret < 0 && ret != -ENOTSUPP) {
+			dev_err(hcd->self.controller,
+				"failed to calibrate USB PHY\n");
+			return ret;
+		}
+	}
+
 	clear_bit(HCD_FLAG_WAKEUP_PENDING, &hcd->flags);
 	if (status == 0) {
 		struct usb_device *udev;
@@ -2742,6 +2754,16 @@ int usb_add_hcd(struct usb_hcd *hcd,
 	}
 	hcd->rh_pollable = 1;
 
+	/* calibrate the phy here */
+	if (!IS_ERR(hcd->gen_phy)) {
+		retval = phy_calibrate(hcd->gen_phy);
+		if (retval < 0 && retval != -ENOTSUPP) {
+			dev_err(hcd->self.controller,
+				"failed to calibrate USB PHY\n");
+			return retval;
+		}
+	}
+
 	/* NOTE: root hub and controller capabilities may not be the same */
 	if (device_can_wakeup(hcd->self.controller)
 			&& device_can_wakeup(&hcd->self.root_hub->dev))
-- 
1.7.10.4

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