[FIX PATCH v1] Fix: common: usb_hub: Reset only USB3.0 hub

[Shantur Rathore]

Hi Marek,

On Wed, Feb 7, 2024 at 1:07 PM Marek Vasut <marex at denx.de> wrote:
>
> On 2/7/24 11:23, Shantur Rathore wrote:
> > USB 3.0 spec requires hub to reset device while
> > enumeration. Some USB 2.0 hubs / devices don't
> > handle this well and after implementation of
> > reset some USB 2.0 disks weren't detected on
> > Allwinner based boards.
> >
> > Resetting only when hub is USB 3.0 fixes it.
>
> It would be good to include as many details about the faulty hardware in
> the commit message as possible, so that when someone else runs into
> this, they would have all that information available.
>
> > Tested-by: Andre Przywara <andre.przywara at arm.com>
> >
> > Signed-off-by: Shantur Rathore <i at shantur.com>
> > ---
> >
> >   common/usb_hub.c | 6 ++++--
> >   1 file changed, 4 insertions(+), 2 deletions(-)
> >
> > diff --git a/common/usb_hub.c b/common/usb_hub.c
> > index 3fb7e14d10..2e054eb935 100644
> > --- a/common/usb_hub.c
> > +++ b/common/usb_hub.c
> > @@ -174,8 +174,10 @@ static void usb_hub_power_on(struct usb_hub_device *hub)
> >
> >       debug("enabling power on all ports\n");
> >       for (i = 0; i < dev->maxchild; i++) {
> > -             usb_set_port_feature(dev, i + 1, USB_PORT_FEAT_RESET);
> > -             debug("Reset : port %d returns %lX\n", i + 1, dev->status);
> > +             if (usb_hub_is_superspeed(dev)) {
>
> Should this condition be "all which are lower than superspeed" instead ,
> so when the next generation of USB comes, this problem won't trigger ?
>
> What does Linux do btw ?

As of now Linux checks if the hub is superspeed
https://github.com/torvalds/linux/blob/master/drivers/usb/core/hub.c#L2859

which is
 return hdev->descriptor.bDeviceProtocol == USB_HUB_PR_SS; // USB_HUB_PR_SS = 3

This holds true for newer SuperSpeedPlus hubs as well.
https://github.com/torvalds/linux/blob/master/drivers/usb/core/hub.h#L155

We can change the check to be  bDeviceProtocol > 2 but who knows if
things change in the newer version of spec.
I am open to suggestions.

Kind regards,
Shantur