linux-kernel - [PATCH v2 1/2] usb: core: phy: add support for PHY calibration

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Date:   Fri, 19 Jul 2019 10:13:16 +0200
From:   Marek Szyprowski <m.szyprowski@...sung.com>
To:     linux-usb@...r.kernel.org, linux-samsung-soc@...r.kernel.org
Cc:     linux-kernel@...r.kernel.org,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        Marek Szyprowski <m.szyprowski@...sung.com>,
        Mathias Nyman <mathias.nyman@...el.com>,
        Felipe Balbi <balbi@...nel.org>,
        Bartlomiej Zolnierkiewicz <b.zolnierkie@...sung.com>,
        Krzysztof Kozlowski <krzk@...nel.org>,
        Jochen Sprickerhof <jochen@...ickerhof.de>,
        Anand Moon <linux.amoon@...il.com>
Subject: [PATCH v2 1/2] usb: core: phy: add support for PHY calibration

Some PHYs (for example Exynos5 USB3.0 DRD PHY) require calibration to be
done after every USB HCD reset. Generic PHY framework has been already
extended with phy_calibrate() function in commit 36914111e682 ("drivers:
phy: add calibrate method"). This patch adds support for it to generic
PHY handling code in USB HCD core.

Signed-off-by: Marek Szyprowski <m.szyprowski@...sung.com>
---
 drivers/usb/core/hcd.c |  7 +++++++
 drivers/usb/core/phy.c | 21 +++++++++++++++++++++
 drivers/usb/core/phy.h |  1 +
 3 files changed, 29 insertions(+)

diff --git a/drivers/usb/core/hcd.c b/drivers/usb/core/hcd.c
index 88533938ce19..b89936c1df23 100644
--- a/drivers/usb/core/hcd.c
+++ b/drivers/usb/core/hcd.c
@@ -2291,6 +2291,9 @@ int hcd_bus_resume(struct usb_device *rhdev, pm_message_t msg)
 	hcd->state = HC_STATE_RESUMING;
 	status = hcd->driver->bus_resume(hcd);
 	clear_bit(HCD_FLAG_WAKEUP_PENDING, &hcd->flags);
+	if (status == 0)
+		status = usb_phy_roothub_calibrate(hcd->phy_roothub);
+
 	if (status == 0) {
 		struct usb_device *udev;
 		int port1;
@@ -2864,6 +2867,10 @@ int usb_add_hcd(struct usb_hcd *hcd,
 	}
 	hcd->rh_pollable = 1;
 
+	retval = usb_phy_roothub_calibrate(hcd->phy_roothub);
+	if (retval)
+		goto err_hcd_driver_setup;
+
 	/* 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))
diff --git a/drivers/usb/core/phy.c b/drivers/usb/core/phy.c
index 7580493b867a..fb1588e7c282 100644
--- a/drivers/usb/core/phy.c
+++ b/drivers/usb/core/phy.c
@@ -151,6 +151,27 @@ int usb_phy_roothub_set_mode(struct usb_phy_roothub *phy_roothub,
 }
 EXPORT_SYMBOL_GPL(usb_phy_roothub_set_mode);
 
+int usb_phy_roothub_calibrate(struct usb_phy_roothub *phy_roothub)
+{
+	struct usb_phy_roothub *roothub_entry;
+	struct list_head *head;
+	int err;
+
+	if (!phy_roothub)
+		return 0;
+
+	head = &phy_roothub->list;
+
+	list_for_each_entry(roothub_entry, head, list) {
+		err = phy_calibrate(roothub_entry->phy);
+		if (err)
+			return err;
+	}
+
+	return 0;
+}
+EXPORT_SYMBOL_GPL(usb_phy_roothub_calibrate);
+
 int usb_phy_roothub_power_on(struct usb_phy_roothub *phy_roothub)
 {
 	struct usb_phy_roothub *roothub_entry;
diff --git a/drivers/usb/core/phy.h b/drivers/usb/core/phy.h
index dad564e2d2d4..20a267cd986b 100644
--- a/drivers/usb/core/phy.h
+++ b/drivers/usb/core/phy.h
@@ -18,6 +18,7 @@ int usb_phy_roothub_exit(struct usb_phy_roothub *phy_roothub);
 
 int usb_phy_roothub_set_mode(struct usb_phy_roothub *phy_roothub,
 			     enum phy_mode mode);
+int usb_phy_roothub_calibrate(struct usb_phy_roothub *phy_roothub);
 int usb_phy_roothub_power_on(struct usb_phy_roothub *phy_roothub);
 void usb_phy_roothub_power_off(struct usb_phy_roothub *phy_roothub);
 
-- 
2.17.1