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

Mon Feb 12 22:10:42 CET 2024

Hello Marek, Andre and Shantur,

On 2024-02-12 21:19, Marek Vasut wrote:
> On 2/12/24 14:41, Shantur Rathore wrote:
>> On Mon, Feb 12, 2024 at 1:40 PM Shantur Rathore <i at shantur.com> wrote:
>>> On Sat, Feb 10, 2024 at 7:13 AM Dragan Simic <dsimic at manjaro.org> 
>>> wrote:
>>>> 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.
> 
> Please send a V2 patch . If possible, include the device information
> as reported by Andre, esp. which USB stick triggered it, including USB
> IDs, this is important for future reference and in case someone has
> similar failure.

If Andre can supply the USB IDs, I'm willing to help Shantur by
adjusting the wording of the patch description to include them.

> Please don't use "in the kernel source, line 2859", considering the
> rate of change of the Linux kernel, it is best to also include exact
> commit ID as of which this is a line 2859 and spell out this is
> referring to Linux kernel.

Good point.  I'm willing to adjust the wording.