[added to the 4.1 stable tree] usb: misc: usb3503: make sure reset is low for at least 100us

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From: Stefan Agner <stefan@xxxxxxxx>

This patch has been added to the 4.1 stable tree. If you have any
objections, please let us know.

===============

[ Upstream commit b8626f1dc29d3eee444bfaa92146ec7b291ef41c ]

When using a GPIO which is high by default, and initialize the
driver in USB Hub mode, initialization fails with:
  [  111.757794] usb3503 0-0008: SP_ILOCK failed (-5)

The reason seems to be that the chip is not properly reset.
Probe does initialize reset low, however some lines later the
code already set it back high, which is not long enouth.

Make sure reset is asserted for at least 100us by inserting a
delay after initializing the reset pin during probe.

Signed-off-by: Stefan Agner <stefan@xxxxxxxx>
Cc: stable <stable@xxxxxxxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
Signed-off-by: Sasha Levin <alexander.levin@xxxxxxxxxxxxx>
---
 drivers/usb/misc/usb3503.c | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/drivers/usb/misc/usb3503.c b/drivers/usb/misc/usb3503.c
index 64ff5b91752d..b117a1f6bfc3 100644
--- a/drivers/usb/misc/usb3503.c
+++ b/drivers/usb/misc/usb3503.c
@@ -292,6 +292,8 @@ static int usb3503_probe(struct usb3503 *hub)
 	if (gpio_is_valid(hub->gpio_reset)) {
 		err = devm_gpio_request_one(dev, hub->gpio_reset,
 				GPIOF_OUT_INIT_LOW, "usb3503 reset");
+		/* Datasheet defines a hardware reset to be at least 100us */
+		usleep_range(100, 10000);
 		if (err) {
 			dev_err(dev,
 				"unable to request GPIO %d as reset pin (%d)\n",
-- 
2.14.1




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