[PATCH] usb: common: ulpi: Fix crash in ulpi_match()

[Jon Hunter <jonathanh@nvidia.com>]

Commit 7495af930835 ("ARM: multi_v7_defconfig: Enable drivers for
DragonBoard 410c") enables the CONFIG_PHY_QCOM_USB_HS for the ARM
multi_v7_defconfig. Enabling this Kconfig is causing the kernel to crash
on the Tegra20 Ventana platform in the ulpi_match() function.

The Qualcomm USB HS PHY driver that is enabled by CONFIG_PHY_QCOM_USB_HS,
registers a ulpi_driver but this driver does not provide an 'id_table',
so when ulpi_match() is called on the Tegra20 Ventana platform, it
crashes when attempting to deference the id_table pointer which is not
valid. The Qualcomm USB HS PHY driver uses device-tree for matching the
ULPI driver with the device and so fix this crash by using device-tree
for matching if the id_table is not valid.

Signed-off-by: Jon Hunter <jonathanh@nvidia.com>
---
 drivers/usb/common/ulpi.c | 7 +++++--
 1 file changed, 5 insertions(+), 2 deletions(-)

diff --git a/drivers/usb/common/ulpi.c b/drivers/usb/common/ulpi.c
index 4169cf40a03b..8f8405b0d608 100644
--- a/drivers/usb/common/ulpi.c
+++ b/drivers/usb/common/ulpi.c
@@ -39,8 +39,11 @@ static int ulpi_match(struct device *dev, struct device_driver *driver)
 	struct ulpi *ulpi = to_ulpi_dev(dev);
 	const struct ulpi_device_id *id;
 
-	/* Some ULPI devices don't have a vendor id so rely on OF match */
-	if (ulpi->id.vendor == 0)
+	/*
+	 * Some ULPI devices don't have a vendor id
+	 * or provide an id_table so rely on OF match.
+	 */
+	if (ulpi->id.vendor == 0 || !drv->id_table)
 		return of_driver_match_device(dev, driver);
 
 	for (id = drv->id_table; id->vendor; id++)
-- 
2.25.1