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

Mon Feb 12 14:40:37 CET 2024

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