[PATCH v2] common: usb-hub: Reset USB 3.0 hubs only

[Shantur Rathore]

Hi Marek,

On Wed, Feb 14, 2024 at 9:55 AM Shantur Rathore <i at shantur.com> wrote:
>
> Additional testing of the changes introduced in commit 33e06dcbe57a "common:
> usb-hub: Reset hub port before scanning") revealed that some USB 2.0 and 3.0
> flash drives didn't work in U-Boot on some Allwinner SoCs that support USB
> 2.0 interfaces only.  More precisely, some of the tested USB 2.0 and 3.0
> flash drives failed to be detected and work on an OrangePi Zero 3, based on
> the Allwinner H616 SoC that supports USB 2.0 only, while the same USB flash
> drives worked just fine on a Pine64 H64, based on the Allwinner H6 SoC that
> supports both USB 2.0 and USB 3.0 interfaces.
>
> The USB ID of the above-mentioned USB 3.0 flash drive that failed to work is
> 1f75:0917 (Innostor Technology Corporation IS917 Mass storage), it is 32 GB
> in size and sold under the PNY brand.  The mentioned USB 2.0 drive is some
> inexpensive no-name drive with an invalid USB ID.
>
> Resetting USB 3.0 hubs only, which this patch introduces to the USB hub
> resets, has been tested to work as expected, resolving the identified issues
> on the Allwinner H616, while not introducing any new issues on other tested
> Allwinner SoCs.  Thus, let's fix it that way.
>
> According to the USB 3.0 specification, resetting a USB 3.0 port is required
> when an attached USB device transitions between different states, such as
> when it resumes from suspend.  Though, the Linux kernel performs additional
> USB 3.0 port resets upon initial USB device attachment, as visible in commit
> 07194ab7be63 ("USB: Reset USB 3.0 devices on (re)discovery") in the kernel
> source, to ensure proper state of the USB 3.0 hub port and proper USB mode
> negotiation during the initial USB device attachment and enumeration.
>
> These additional types of USB port resets don't exist for USB 2.0 hubs,
> according the USB 2.0 specification.  The resets seem to be added to the USB
> 3.0 specification as part of the port and device mode negotiation.
>
> The Linux kernel resets USB 3.0 (i.e. SuperSpeed) hubs only, as visible in
> commit 10d674a82e55 ("USB: When hot reset for USB3 fails, try warm reset.")
> in the kernel source.  The check for SuperSpeed hubs is performed in a way
> that also applies to newer SuperSpeed Plus (USB 3.1 or 3.2) hubs as well,
> which hopefully makes it future proof.
>
> Fixes: commit 33e06dcbe57a ("common: usb-hub: Reset hub port before scanning")
>
> Link:
> https://lore.kernel.org/u-boot/20240207102327.35125-1-i@shantur.com/T/#u
> Link:
> https://lore.kernel.org/u-boot/20240201164604.13315fa6@donnerap.manchester.arm.com/T/#u
>
> Signed-off-by: Shantur Rathore <i at shantur.com>
> Helped-by: Dragan Simic <dsimic at manjaro.org>
> Tested-by: Andre Przywara <andre.przywara at arm.com>
> Reviewed-by: Dragan Simic <dsimic at manjaro.org>
>
> ---
>
> (no changes since v1)
>
>  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)) {
> +                       usb_set_port_feature(dev, i + 1, USB_PORT_FEAT_RESET);
> +                       debug("Reset : port %d returns %lX\n", i + 1, dev->status);
> +               }
>                 usb_set_port_feature(dev, i + 1, USB_PORT_FEAT_POWER);
>                 debug("PowerOn : port %d returns %lX\n", i + 1, dev->status);
>         }
> --
> 2.40.1
>

Is it possible to get this in before the next RC?

Regards,
Shantur