[PATCH v3] common: usb-hub: Reset hub port before scanning

[Shantur Rathore]

Hi Andre,

On Tue, Jan 30, 2024 at 2:01 PM Andre Przywara <andre.przywara at arm.com> wrote:
>
> On Sat,  9 Dec 2023 18:10:56 +0000
> Shantur Rathore <i at shantur.com> wrote:
>
> Hi,
>
> > Currently when a hub is turned on, all the ports are powered on.
> > This works well for hubs which have individual power control.
> >
> > For the hubs without individual power control this has no effect.
> > Mostly in these scenarios the hub port is powered before the USB
> > controller is enabled, this can lead to some devices in unexpected
> > state.
> >
> > With this patch, we explicitly reset the port while powering up hub
> > This resets the port for hubs without port power control and has
> > no effect on hubs with port power control as the port is still off.
> >
> > Before this patch AMicro AM8180 based NVME to USB adapter won't be
> > detected as a USB3.0 Mass Storage device but with this it works as
> > expected.
> >
> > Tested working after this patch:
> > 1. AMicro AM8180 based NVME to USB Adapter
> > 2. Kingston DataTraveler 3.0
> > 3. GenesysLogic USB3.0 Hub
> >
> > The drives were tested while connected directly and via the hub.
>
> so this broke USB operation on some Allwinner boards. The ports still
> enumerate correctly, but no devices are detected. With mainline
> (containing this patch), and a USB stick connected:
> starting USB...
> Bus usb at 5200000: USB EHCI 1.00
> Bus usb at 5200400: USB OHCI 1.0
> scanning bus usb at 5200000 for devices... 1 USB Device(s) found
> scanning bus usb at 5200400 for devices... 1 USB Device(s) found
>        scanning usb for storage devices... 0 Storage Device(s) found
>
> With this patch here reverted:
> starting USB...
> Bus usb at 5200000: USB EHCI 1.00
> Bus usb at 5200400: USB OHCI 1.0
> scanning bus usb at 5200000 for devices... 2 USB Device(s) found
> scanning bus usb at 5200400 for devices... 1 USB Device(s) found
>        scanning usb for storage devices... 1 Storage Device(s) found
>
> I have no clue why this happens, there is no discrete hub anywhere in this
> setup, so I guess the code runs for the root hub here?
> I am attaching a log with DEBUG enabled for common/usb_hub.c, for both
> cases.
>
> Any clues, debug suggestions, or even a fix are warmly welcome.
>

Which USB disk are you using? Is it a USB 2.0 disk ?
Can you try with any other USB disk to confirm?

Regards,
Shantur