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From: Peter Zijlstra <peterz@infradead.org>
To: baolu.lu@linux.intel.com
Cc: x86@kernel.org, linux-kernel@vger.kernel.org,
	gregkh@linuxfoundation.org, linux-usb@vger.kernel.org
Subject: earlyprintk=xdbc seems broken
Date: Thu, 2 Dec 2021 16:22:55 +0100	[thread overview]
Message-ID: <YajkzwmWQua3Kh6A@hirez.programming.kicks-ass.net> (raw)

Hi Lu,

I was unfortunate enough to need xdbc and can't get my machine to boot
with earlyprintk=xdbc on the cmdline.

When I boot the target without the earlyprintk=xdbc, but have the cable
attached, it won't boot because boot gets stuck like:

Dec  2 15:08:10 tigerlake kernel: [   42.043137] usb usb4-port3: Cannot enable. Maybe the USB cable is bad?
Dec  2 15:08:10 tigerlake kernel: [   42.043227] usb usb4-port3: config error

However, when I boot without earlyprintk=xdbc, without the cable
attached, then I can attach the cable and:

$ echo enable > /sys/bus/pci/devices/0000:00:14.0/dbc

will actually work, and it shows up on my host system:

[1023855.419430] usb usb2-port3: Cannot enable. Maybe the USB cable is bad?
[1023855.419455] usb usb2-port3: config error
[1023859.491476] usb usb2-port3: Cannot enable. Maybe the USB cable is bad?
[1023859.491487] usb usb2-port3: config error
[1023861.335436] usb usb2-port3: config error
[1023861.607476] usb 2-3: new SuperSpeed USB device number 7 using xhci_hcd
[1023861.627614] usb 2-3: LPM exit latency is zeroed, disabling LPM.
[1023861.627853] usb 2-3: New USB device found, idVendor=1d6b, idProduct=0010, bcdDevice= 0.10
[1023861.627855] usb 2-3: New USB device strings: Mfr=1, Product=2, SerialNumber=3
[1023861.627856] usb 2-3: Product: Linux USB Debug Target
[1023861.627857] usb 2-3: Manufacturer: Linux Foundation
[1023861.627858] usb 2-3: SerialNumber: 0001
[1023861.629344] usb_debug 2-3:1.0: xhci_dbc converter detected
[1023861.629532] usb 2-3: xhci_dbc converter now attached to ttyUSB0


Can you please see if you can repro and fix this?

This all was with current 5.16-rc3 on a tigerlake nuc.

Also, perhaps you can update the guide on what sort of setup/cables
etc.. you need when either the host or the client is a usb3.1 usb-c only
device.

             reply	other threads:[~2021-12-02 17:30 UTC|newest]

Thread overview: 32+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-12-02 15:22 Peter Zijlstra [this message]
2021-12-03  0:52 ` earlyprintk=xdbc seems broken Lu Baolu
2021-12-03 14:31   ` Mathias Nyman
2021-12-03 15:22     ` Dave Hansen
2021-12-03 15:29       ` Greg KH
2021-12-17 11:01         ` Mathias Nyman
2021-12-17 13:55           ` Peter Zijlstra
2021-12-17 15:19             ` Greg KH
2021-12-20 14:40               ` Peter Zijlstra
2021-12-20 15:06                 ` Greg KH
2021-12-20 17:01                   ` Peter Zijlstra
2021-12-20 14:34             ` Mathias Nyman
2021-12-20 15:51               ` Peter Zijlstra
2021-12-21  9:40             ` Peter Zijlstra
2021-12-21  9:41               ` Peter Zijlstra
2022-01-14  8:47               ` Peter Zijlstra
2022-01-14 19:31                 ` Mathias Nyman
2022-01-15 16:06                   ` Peter Zijlstra
2022-01-24 14:55                     ` Mathias Nyman
2022-01-24 16:39                       ` Peter Zijlstra
2022-01-24 16:46                         ` Peter Zijlstra
2022-01-25  8:51                           ` Mathias Nyman
2022-01-25 10:47                             ` Peter Zijlstra
2022-01-25 10:54                               ` Peter Zijlstra
2022-01-25 12:45                       ` Peter Zijlstra
2022-01-25 13:09                         ` Sven Schnelle
2022-01-25 13:54                           ` Peter Zijlstra
2022-01-25 14:01                             ` Sven Schnelle
2022-01-25 17:13                               ` Mathias Nyman
2022-01-25 16:24                           ` Dave Hansen
2022-02-17  3:44                             ` Randy Dunlap
2022-01-25 19:39                         ` Rajaram R

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