Re: USB hub problem

[Felipe Balbi <balbi@kernel.org>]

Hi,

Eyal Lebedinsky <eyal@eyal.emu.id.au> writes:
> On 15/08/2021 16.28, Greg KH wrote:
>> On Sun, Aug 15, 2021 at 09:32:06AM +1000, Eyal Lebedinsky wrote:
>>> I have an external 4-way USB3.0 hub (I actually have two of them) That do not behave as expected.
>>> It is an XCD XCDESSUSBH4BK. It is unpowered. I am on fedora 34, kernel 5.13.8-200.fc34.x86_64
>>>
>>> For starters, I found that attaching a USB SSD does not allow booting from it.
>> That is up to your BIOS, not Linux.
>
> Attaching the USB SSD directly to the PC does boot from it though.

right, booting happens way before the OS gets a chance to run. Sounds
like a BIOS issue.

>>> I then found that when attaching my phone it is not recognized.
>> In what way?
>> 
>>> I searched the hub model and IDs but did not find relevant information.
>>> Is there an official list of supported hubs (or devices)?
>> No, as any list would instantly be out of date.
>> 
>>> Here is what it looks like.
>>>
>>> When the hub is attached (no phone) I see
>>>          Bus 001 Device 048: ID 0bda:5411 Realtek Semiconductor Corp. RTS5411 Hub
>>> and
>>>          /:  Bus 01.Port 1: Dev 1, Class=root_hub, Driver=xhci_hcd/16p, 480M
>>>              |__ Port 5: Dev 5, If 0, Class=Hub, Driver=hub/4p, 480M
>>>                  |__ Port 2: Dev 48, If 0, Class=Hub, Driver=hub/4p, 480M
>>> Attaching the phone does not add a device.
>>>
>>> Detaching/attaching the hub (with the phone already plugged in) I get
>>>          Bus 001 Device 052: ID 04e8:6860 Samsung Electronics Co., Ltd Galaxy A5 (MTP)
>>>          Bus 001 Device 051: ID 0bda:5411 Realtek Semiconductor Corp. RTS5411 Hub
>>> and
>>>          /:  Bus 01.Port 1: Dev 1, Class=root_hub, Driver=xhci_hcd/16p, 480M
>>>              |__ Port 5: Dev 5, If 0, Class=Hub, Driver=hub/4p, 480M
>>>                  |__ Port 2: Dev 51, If 0, Class=Hub, Driver=hub/4p, 480M
>>>                      |__ Port 1: Dev 52, If 1, Class=Communications, Driver=cdc_acm, 480M
>>>                      |__ Port 1: Dev 52, If 2, Class=CDC Data, Driver=cdc_acm, 480M
>>>                      |__ Port 1: Dev 52, If 0, Class=Imaging, Driver=, 480M
>>>                      |__ Port 1: Dev 52, If 3, Class=Vendor Specific Class, Driver=, 480M
>>> and the phone is recognized and accessible as MTP device.
>> Great, so when does this not work?  This shows a successful device
>> found.
>
> Yes, this does show success, but earlier there is this failure shown:
> 	## plug phone:
>         	(no new messages)
>
> In other words, the system did not notice the phone when it was
> plugged into that hub.

does anything work when plugged to that hub? Is the hub self-powered or
bus powered?

> I then attached the hub to the machine with the phone already plugged
> into it and it was noticed.
>
> My suspicion is that the hub is at fault and it fails to report the
> (phone plugged in) event so linux probably has no knowledge of this.
>
> What I failed to mention is that plugging a USB disk into this hub IS
> recognized as expected.  Something is not happy between the phone and
> this hub.
>
> Plugging the phone to other USB 3.0 ports on this machine is
> recognized properly.

do you have other hubs around to test?

-- 
balbi