patch "usb: dwc3: exynos: Fix deferred probing storm." added to usb-linus

gregkh
2016-06-01T21:50:48Z

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

usb: dwc3: exynos: Fix deferred probing storm.

to my usb git tree which can be found at
git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/usb.git
in the usb-linus branch.

The patch will show up in the next release of the linux-next tree
(usually sometime within the next 24 hours during the week.)

The patch will hopefully also be merged in Linus's tree for the
next -rc kernel release.

If you have any questions about this process, please let me know.

>From 4879efb34f7d49235fac334d76d9c6a77a021413 Mon Sep 17 00:00:00 2001
From: "Steinar H. Gunderson" <sesse@google.com>
Date: Tue, 24 May 2016 20:13:15 +0200
Subject: usb: dwc3: exynos: Fix deferred probing storm.

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.

Signed-off-by: Steinar H. Gunderson <sesse@google.com>
Reviewed-by: Krzysztof Kozlowski <k.kozlowski@samsung.com>
Reviewed-by: Vivek Gautam <gautam.vivek@samsung.com>
Fixes: d720f057fda4 ("usb: dwc3: exynos: add nop transceiver support")
Cc: <stable@vger.kernel.org>
Signed-off-by: Felipe Balbi <felipe.balbi@linux.intel.com>
---
drivers/usb/dwc3/dwc3-exynos.c | 19 +++++++++++--------
1 file changed, 11 insertions(+), 8 deletions(-)

diff --git a/drivers/usb/dwc3/dwc3-exynos.c b/drivers/usb/dwc3/dwc3-exynos.c
index dd5cb5577dca..2f1fb7e7aa54 100644
--- a/drivers/usb/dwc3/dwc3-exynos.c
+++ b/drivers/usb/dwc3/dwc3-exynos.c
@@ -128,12 +128,6 @@ static int dwc3_exynos_probe(struct platform_device *pdev)

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 platform_device *pdev)
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:
--
2.8.3