Hi Alan,
I am working on an new USB3 DRD IP development, in order to avoid the
problem that the DRD core device drvdata is overwritten by usb_hcd
at __usb_create_hcd [1], I create one device as DRD core device's child
for USB core (as controller device from USB core point), the device hierarchy
likes below:
DRD core device (IP device, like dwc3/chipidea)
|
|
---------------
| |
ip-xhci-dev ip-gadget-dev
| |
roothub gadget
But this device (ip-xhci-dev) has no device_driver, in that case, the
udev->bus->controller->driver is NULL, so at hub_port_init, it
shows NULL pointer oops during the enumeration.
In order to fix this problem, my temp solution is using sysdev instead
of udev->bus->controller, see below:
commit 8fb6057bd59ebb6985dc39ebf41ad7f13ea41b70
Author: Peter Chen <peter.chen@xxxxxxx>
Date: Thu Jun 8 14:37:25 2017 +0800
usb: core: hub: fix NULL pointer for driver->name
Signed-off-by: Peter Chen <peter.chen@xxxxxxx>
diff --git a/drivers/usb/core/hub.c b/drivers/usb/core/hub.c
index 96c66d7..0d7b4eb 100644
--- a/drivers/usb/core/hub.c
+++ b/drivers/usb/core/hub.c
@@ -4399,7 +4399,8 @@ hub_port_init(struct usb_hub *hub, struct usb_device *udev, int port1,
dev_info(&udev->dev,
"%s %s USB device number %d using %s\n",
(udev->config) ? "reset" : "new", speed,
- devnum, udev->bus->controller->driver->name);
+ devnum, udev->bus->controller->driver ? udev->bus->controller->driver->name :
+ udev->bus->sysdev->driver->name);
/* Set up TT records, if needed */
if (hdev->tt) {
@@ -4532,7 +4533,8 @@ hub_port_init(struct usb_hub *hub, struct usb_device *udev, int port1,
"%s SuperSpeed%s USB device number %d using %s\n",
(udev->config) ? "reset" : "new",
(udev->speed == USB_SPEED_SUPER_PLUS) ? "Plus" : "",
- devnum, udev->bus->controller->driver->name);
+ devnum, udev->bus->controller->driver ? udev->bus->controller->driver->name :
+ udev->bus->sysdev->driver->name);
}
/* cope with hardware quirkiness:
But I think above changes may not good enough, do you have any
suggestions?
If there is no good solution for fixing it, how about just using core device
as parent for roothub, this is what chipidea does now?
Since the xhci has no /sys interfaces like ehci at ehci-sysfs.c implements,
it is ok for now, but I am not sure if the USB core will use platform device's
drvdata in the future, like what usb_hcd_platform_shutdown does.
Thanks.
[1] https://www.spinics.net/lists/linux-usb/msg128599.html
--
Best Regards,
Peter Chen
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