On Thu, 24 Aug 2006, Iñaky Pérez-González wrote:
> > That's not so easy either. The fact is, hdev_to_hub() _isn't_ safe unless
> > you possess some extra prior knowledge.
>
> which priori knowledge? I had assumed that as long as it has registered,
> we were safe.
It's not enough for it to be registered; you have to know also that it is
bound to the hub driver. And it can be unbound at almost any time, so you
have to be in a context where you know that unbinding is blocked. For
instance, if you own the hub's device lock, or the lock for one of its
connected children, then you're safe. hub_port_wait_reset is one of those
safe places.
Although I see below in your new code you don't need to use hdev_to_hub at
all. Which is a good thing.
> There are no hubs per se in WUSB, hosts only have a 'virtual' root hub with
> 'virtual' ports. Devices plug directly to that.
>
> Now, devices in WUSB are all variable speed. Someone added USB_SPEED_VARIABLE
> in usb_ch9.h for wireless, so I reused that. It is kind of like the mark
> that says 'these are WUSB devices'.
Okay, I get it.
> Ok, so then it'd boil down to:
>
> /** @returns 1 if hub is a WUSB root hub, 0 otherwise */
> static
> unsigned hub_is_wusb(struct usb_hub *hub)
> {
> struct usb_hcd *hcd;
> if (hub->hdev->parent != NULL) // no root hub?
Make that comment: // not a root hub?
> return 0;
> hcd = container_of(hub->hdev->bus, struct usb_hcd, self);
> return hcd->wireless;
> }
>
> hub_port_wait_reset()
> {
> ...
> if (hub_is_wusb(hub))
> udev->speed = USB_SPEED_VARIABLE;
> else if (portstatus & USB_PORT_STAT_HIGH_SPEED)
> ...
> ...
> }
>
> How does this look?
It looks good.
Alan Stern
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