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

[Dragan Simic]

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
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 -------