Patch "usb: dwc3: exynos: Fix deferred probing storm." has been added to the 4.6-stable tree

This is a note to let you know that I've just added the patch titled

usb: dwc3: exynos: Fix deferred probing storm.

to the 4.6-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary

The filename of the patch is:
usb-dwc3-exynos-fix-deferred-probing-storm.patch
and it can be found in the queue-4.6 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree, please let <[email protected]> know about it.

From: "Steinar H. Gunderson" <[email protected]>
Date: Tue, 24 May 2016 20:13:15 +0200
Subject: usb: dwc3: exynos: Fix deferred probing storm.

From: Steinar H. Gunderson <[email protected]>

commit 4879efb34f7d49235fac334d76d9c6a77a021413 upstream.

dwc3-exynos has two problems during init if the regulators are slow to come up (for instance if the I2C bus driver is not on the initramfs) and return probe deferral. First, every time this happens, the driver leaks the USB phys created; they need to be deallocated on error.

Second, since the phy devices are created before the regulators fail, this means that there's a new device to re-trigger deferred probing, which causes it to essentially go into a busy loop of re-probing the device until the regulators come up.

Move the phy creation to after the regulators have succeeded, and also fix cleanup on failure. On my ODROID XU4 system (with Debian's initramfs which doesn't contain the I2C driver), this reduces the number of probe attempts (for each of the two controllers) from more than 2000 to eight.

---
 drivers/usb/dwc3/dwc3-exynos.c |   19 +++++++++++--------
 1 file changed, 11 insertions(+), 8 deletions(-)

@@ -128,12 +128,6 @@ static int dwc3_exynos_probe(struct plat
 
 	platform_set_drvdata(pdev, exynos);
 
-	ret = dwc3_exynos_register_phys(exynos);
-	if (ret) {
-		dev_err(dev, "couldn't register PHYs\n");
-		return ret;
-	}
-
 	exynos->dev	= dev;
 
 	exynos->clk = devm_clk_get(dev, "usbdrd30");

@@ -183,20 +177,29 @@ static int dwc3_exynos_probe(struct plat
 		goto err3;
 	}
 
+	ret = dwc3_exynos_register_phys(exynos);
+	if (ret) {
+		dev_err(dev, "couldn't register PHYs\n");
+		goto err4;
+	}
+
 	if (node) {
 		ret = of_platform_populate(node, NULL, NULL, dev);
 		if (ret) {
 			dev_err(dev, "failed to add dwc3 core\n");
-			goto err4;
+			goto err5;
 		}
 	} else {
 		dev_err(dev, "no device node, failed to add dwc3 core\n");
 		ret = -ENODEV;
-		goto err4;
+		goto err5;
 	}
 
 	return 0;
 
+err5:
+	platform_device_unregister(exynos->usb2_phy);
+	platform_device_unregister(exynos->usb3_phy);
 err4:
 	regulator_disable(exynos->vdd10);
 err3:

Patches currently in stable-queue which might be from [email protected] are

queue-4.6/usb-dwc3-exynos-fix-deferred-probing-storm.patch