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

Mon Feb 12 14:41:24 CET 2024

On Mon, Feb 12, 2024 at 1:40 PM Shantur Rathore <i at shantur.com> wrote:
>
> Thanks Dragan,
>
> On Sat, Feb 10, 2024 at 7:13 AM Dragan Simic <dsimic at manjaro.org> wrote:
> >
> > Hello Shantur,
> >
> > On 2024-02-08 15:17, Dragan Simic wrote:
> > > On 2024-02-08 15:10, Shantur Rathore wrote:
> > >> On Thu, Feb 8, 2024 at 1:44 PM Dragan Simic <dsimic at manjaro.org>
> > >> wrote:
> > >>> On 2024-02-08 14:33, Marek Vasut wrote:
> > >>> > On 2/8/24 12:30, Shantur Rathore wrote:
> > >>> >> 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.
> > >>> >
> > >>> > Please just include the ^ in the commit description. Use link to
> > >>> > git.kernel.org , not some mirror . This is extremely useful
> > >>> > information and, well, you already wrote the V2 commit message
> > >>> > addition in this answer.
> > >>>
> > >>> Shantur, if that would be easier or quicker for you, I can write
> > >>> a quite detailed patch description for you, in exchange for a
> > >>> "Helped-by" tag in the v2 patch submission. :)
> > >>
> > >> That would be really kind of you Dragan.
> > >
> > > Sure, I'll write the summary and send it over.
> > >
> > >> I am down with the flu so that would really help me as my brain is
> > >> working at 15% capacity.
> > >
> > > Oh, I'm really sorry to hear that. :(  I hope you'll get better
> > > soon, and I know very well what's it like;  I've also been sick
> > > recently, as a result of some kind of flu that unfortunately found
> > > its way into my lungs, and it took me about a month to get back
> > > to about 90% of my usual mental capacity.  I'm still not back to
> > > exactly 100%. :/
> > >
> > > I really hope you'll recover much faster.
> >
> > I hope you're feeling better.
> >
> > Below are the patch subject and description that I prepared for you,
> > please have a look.
> >
> > ------- >8 ------------- >8 ------------- >8 ------------- >8 -------
> > [PATCH v2] common: usb-hub: Reset USB 3.0 hubs only
> >
> > Additional testing of the changes introduced in commit 33e06dcbe57a
> > ("common:
> > usb-hub: Reset hub port before scanning") revealed that some USB 3.0
> > flash
>
> I think it was a USB 2.0 drive that didn't work on the USB 2.0 port.
>
> > drives didn't work in U-Boot on some Allwinner SoCs that support USB 2.0
> > only.
> > More precisely, some tested USB 3.0 flash drives failed to be detected
> > and
> > work on an OrangePi Zero 3 with Allwinner H616 SoC, which supports USB
> > 2.0
> > only, while the same USB flash drives worked just fine on a Pine64 H64
> > with
> > Allwinner H6 SoC, which supports both USB 2.0 and 3.0.
> >
> > Resetting USB 3.0 hubs only has been tested to work as expected,
> > resolving
> > the previous issues on the Allwinner H616, while not introducing any new
> > issues on other 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, presumably to
> > ensure
> > proper state of the USB 3.0 hub port and proper USB mode negotiation
> > during
> > the initial USB device attachment and enumeration.
> >
> > Such USB port resets don't seem to 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 also resets USB 3.0 (i.e. SuperSpeed) hubs only, as
> > visible
> > in file drivers/usb/core/hub.c in the kernel source, line 2859.  This
> > check
> > also applies to newer SuperSpeed Plus (USB 3.1 or 3.2) hubs as well,
> > which
> > hopefully makes it future proof.
> >
> > Fixes: 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>
> > ------- >8 ------------- >8 ------------- >8 ------------- >8 -------
>
> Regards,
> Shantur

Is this description acceptable to you Marek.

Thanks,
Shantur