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

[Shantur Rathore]

On Thu, Feb 1, 2024 at 11:13 AM Marek Vasut <marex at denx.de> wrote:
>
> On 2/1/24 10:39, Shantur Rathore wrote:
> > 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?
>
> I don't think this is device specific, see the logs. Hardware from Andre
> worked before this patch, does not work after this patch. There seem to
> be no connection event with this patch.

I am trying to evaluate if this is happening due to a USB 2.0 device.
I see that the host is USB 2.0. I have tested this on my RK3399 board on both
USB 2.0 and USB 3.0 ports.
If this is not behaving on USB 2.0 ports then I can put a condition
for this to happen
only on USB 3.0 ports.