[PATCH v3] usb: chipidea: ci_hdrc_imx: Also search for 'phys' phandle

[Fabio Estevam <festevam@gmail.com>]

When passing 'phys' in the devicetree to describe the USB PHY phandle
(which is the recommended way according to
Documentation/devicetree/bindings/usb/ci-hdrc-usb2.txt) the
following NULL pointer dereference is observed on i.MX7 and i.MX8MM:

[    1.489344] Unable to handle kernel NULL pointer dereference at virtual address 0000000000000098
[    1.498170] Mem abort info:
[    1.500966]   ESR = 0x96000044
[    1.504030]   EC = 0x25: DABT (current EL), IL = 32 bits
[    1.509356]   SET = 0, FnV = 0
[    1.512416]   EA = 0, S1PTW = 0
[    1.515569]   FSC = 0x04: level 0 translation fault
[    1.520458] Data abort info:
[    1.523349]   ISV = 0, ISS = 0x00000044
[    1.527196]   CM = 0, WnR = 1
[    1.530176] [0000000000000098] user address but active_mm is swapper
[    1.536544] Internal error: Oops: 96000044 [#1] PREEMPT SMP
[    1.542125] Modules linked in:
[    1.545190] CPU: 3 PID: 7 Comm: kworker/u8:0 Not tainted 5.14.0-dirty #3
[    1.551901] Hardware name: Kontron i.MX8MM N801X S (DT)
[    1.557133] Workqueue: events_unbound deferred_probe_work_func
[    1.562984] pstate: 80000005 (Nzcv daif -PAN -UAO -TCO BTYPE=--)
[    1.568998] pc : imx7d_charger_detection+0x3f0/0x510
[    1.573973] lr : imx7d_charger_detection+0x22c/0x510

This happens because the charger functions check for the phy presence
inside the imx_usbmisc_data structure (data->usb_phy), but the chipidea
core populates the usb_phy passed via 'phys' inside 'struct ci_hdrc'
(ci->usb_phy) instead.

This causes the NULL pointer dereference inside imx7d_charger_detection().

Fix it by also searching for 'phys' in case 'fsl,usbphy' is not found.

Tested on a imx7s-warp board.

Cc: stable@vger.kernel.org
Fixes: 746f316b753a ("usb: chipidea: introduce imx7d USB charger detection")
Reported-by: Heiko Thiery <heiko.thiery@gmail.com>
Signed-off-by: Fabio Estevam <festevam@gmail.com>
Reviewed-by: Frieder Schrempf <frieder.schrempf@kontron.de>
---
Changes since v2:

- Added Frieder's reviewed-by tag.
- Cc stable
- Improved the commit log and fixed typo in 'dereferenced'

 drivers/usb/chipidea/ci_hdrc_imx.c | 15 ++++++++++-----
 1 file changed, 10 insertions(+), 5 deletions(-)

diff --git a/drivers/usb/chipidea/ci_hdrc_imx.c b/drivers/usb/chipidea/ci_hdrc_imx.c
index 8b7bc10b6e8b..f1d100671ee6 100644
--- a/drivers/usb/chipidea/ci_hdrc_imx.c
+++ b/drivers/usb/chipidea/ci_hdrc_imx.c
@@ -420,11 +420,16 @@ static int ci_hdrc_imx_probe(struct platform_device *pdev)
 	data->phy = devm_usb_get_phy_by_phandle(dev, "fsl,usbphy", 0);
 	if (IS_ERR(data->phy)) {
 		ret = PTR_ERR(data->phy);
-		/* Return -EINVAL if no usbphy is available */
-		if (ret == -ENODEV)
-			data->phy = NULL;
-		else
-			goto err_clk;
+		if (ret == -ENODEV) {
+			data->phy = devm_usb_get_phy_by_phandle(dev, "phys", 0);
+			if (IS_ERR(data->phy)) {
+				ret = PTR_ERR(data->phy);
+				if (ret == -ENODEV)
+					data->phy = NULL;
+				else
+					goto err_clk;
+			}
+		}
 	}
 
 	pdata.usb_phy = data->phy;
-- 
2.25.1