[Feature] Add xHCI debug device support in the driver

[Alice Liu]

Description

xHCI compatible USB host controllers(i.e. super-speed USB3 controllers)
can be implemented with the Debug Capability(DbC). It presents a debug
device which is fully compliant with the USB framework and provides the
equivalent of a very high performance full-duplex serial link. The debug
capability operation model and registers interface are defined in 7.6.8
of the xHCI specification, revision 1.1.

The DbC debug device shares a root port with the xHCI host. By default,
the debug capability is disabled and the root port is assigned to xHCI.
When the DbC is enabled, the root port will be assigned to the DbC debug
device, and the xHCI sees nothing on this port. This implementation uses
a sysfs node named <dbc> under the xHCI device to manage the enabling
and disabling of the debug capability.

When the debug capability is enabled, it will present a debug device
through the debug port. This debug device is fully compliant with the
USB3 framework, and it can be enumerated by a debug host on the other
end of the USB link. As soon as the debug device is configured, a TTY
serial device named /dev/ttyDBC0 will be created.

One use of this link is running a login service on the debug target.
Hence it can be remote accessed by a debug host. Another use case can
probably be found in servers. It provides a peer-to-peer USB link
between two host-only machines. This provides a reasonable out-of-band
communication method between two servers.

Target Kernel: 4.16
Target Release: 18.04

[Leann Ogasawara (leannogasawara)]

Is there a list of commits we should confirm for 18.04?

[Alice Liu (dxliu)]

Merged in kernel v4.16-rc1.
Commit id:
dfba2174dc421ecad8dc50741054a305cd3ba681

[Joseph Salisbury (jsalisbury)]

https://lists.ubuntu.com/archives/kernel-team/2018-March/090558.html

[Launchpad Janitor (janitor)]

This bug was fixed in the package linux - 4.15.0-12.13

---------------
linux (4.15.0-12.13) bionic; urgency=medium

  * linux: 4.15.0-12.13 -proposed tracker (LP: #1754059)

  * CONFIG_EFI=y on armhf (LP: #1726362)
    - [Config] CONFIG_EFI=y on armhf, reconcile secureboot EFI settings

  * ppc64el: Support firmware disable of RFI flush (LP: #1751994)
    - powerpc/pseries: Support firmware disable of RFI flush
    - powerpc/powernv: Support firmware disable of RFI flush

  * [Feature] CFL/CNL (PCH:CNP-H): New GPIO Commit added (GPIO Driver needed)
    (LP: #1751714)
    - gpio / ACPI: Drop unnecessary ACPI GPIO to Linux GPIO translation
    - pinctrl: intel: Allow custom GPIO base for pad groups
    - pinctrl: cannonlake: Align GPIO number space with Windows

  * [Feature] Add xHCI debug device support in the driver (LP: #1730832)
    - usb: xhci: Make some static functions global
    - usb: xhci: Add DbC support in xHCI driver
    - [Config] USB_XHCI_DBGCAP=y for commit mainline dfba2174dc42.

  * [SRU] Lenovo E41 Mic mute hotkey is not responding (LP: #1753347)
    - platform/x86: ideapad-laptop: Increase timeout to wait for EC answer

  * headset mic can't be detected on two Dell machines (LP: #1748807)
    - ALSA: hda - Fix a wrong FIXUP for alc289 on Dell machines

  * hisi_sas: Add disk LED support (LP: #1752695)
    - scsi: hisi_sas: directly attached disk LED feature for v2 hw

  * [Feature] [Graphics]Whiskey Lake (Coffelake-U 4+2) new PCI Device ID adds
    (LP: #1742561)
    - drm/i915/cfl: Adding more Coffee Lake PCI IDs.

  * [Bug] [USB Function][CFL-CNL PCH]Stall Error and USB Transaction Error in
    trace, Disable of device-initiated U1/U2 failed and rebind failed: -517
    during suspend/resume with usb storage. (LP: #1730599)
    - usb: Don't print a warning if interface driver rebind is deferred at resume

  * retpoline: ignore %cs:0xNNN constant indirections (LP: #1752655)
    - [Packaging] retpoline -- elide %cs:0xNNNN constants on i386
    - [Config] retpoline -- clean up i386 retpoline files

  * hisilicon hibmc regression due to ea642c3216cb ("drm/ttm: add io_mem_pfn
    callback") (LP: #1738334)
    - drm/ttm: add ttm_bo_io_mem_pfn to check io_mem_pfn

  * [Asus UX360UA] battery status in unity-panel is not changing when battery is
    being charged (LP: #1661876) // AC adapter status not detected on Asus
    ZenBook UX410UAK (LP: #1745032)
    - ACPI / battery: Add quirk for Asus UX360UA and UX410UAK

  * ASUS UX305LA - Battery state not detected correctly (LP: #1482390)
    - ACPI / battery: Add quirk for Asus GL502VSK and UX305LA

  * [18.04 FEAT] Automatically detect layer2 setting in the qeth device driver
    (LP: #1747639)
    - s390/diag: add diag26c support for VNIC info
    - s390/qeth: support early setup for z/VM NICs

  * Bionic update to v4.15.7 stable release (LP: #1752317)
    - netfilter: drop outermost socket lock in getsockopt()
    - arm64: mm: don't write garbage into TTBR1_EL1 register
    - kconfig.h: Include compiler types to avoid missed struct attributes
    - MIPS: boot: Define __ASSEMBLY__ for its.S build
    - xtensa: fix high memory/reserved memory collision
    - scsi: ibmvfc: fix misde...

[Brad Figg (brad-figg)]

This bug is awaiting verification that the kernel in -proposed solves the problem. Please test the kernel and update this bug with the results. If the problem is solved, change the tag 'verification-needed-bionic' to 'verification-done-bionic'. If the problem still exists, change the tag 'verification-needed-bionic' to 'verification-failed-bionic'.

If verification is not done by 5 working days from today, this fix will be dropped from the source code, and this bug will be closed.

See https://wiki.ubuntu.com/Testing/EnableProposed for documentation how to enable and use -proposed. Thank you!

[Andy Whitcroft (apw)]

This bug was erroneously marked for verification in bionic; verification is not required and verification-needed-bionic is being removed.