[bionic] Support Intel Atom (Baytrail-I) HS-UART serdev slaves over tty

Bug #1864147 reported by Shrirang Bagul
6
This bug affects 1 person
Affects Status Importance Assigned to Milestone
linux (Ubuntu)
Confirmed
High
Unassigned
Bionic
Confirmed
High
Unassigned

Bug Description

[SRU Justification]

[Impact]
Support Intel Atom (Baytrail-I) HS-UART serdev slaves over tty

On systems using Intel Atom (Baytrail-I) SoC's, slave devices connected on
HSUART1/2 ports are described by the ACPI BIOS as virtual hardware using
HID's INT3511/INT3512.

As a consequence, HW manufacturers have complete freedom to install any
devices on-board as long as they can be accessed over serial tty
interface. Once such device is Dell Edge 3002 IoT Gateway which sports
ZigBee & GPS devices on the HS-UART ports 1 & 2 respectively.

Post 4.15, with CONFIG_SERIAL_DEV_BUS=y, serdev port controller driver
handles the enumeration for the slaves connected on these ports. Also,
/dev/ttySx device nodes for these ports are no longer exposed to the
userspace.

[Fixes]
This patchset allows the skipped virtual UART's with ACPI HID's mentioned
above to be enumerated as ttyHSx port.

[Regression Potential]
Low. This driver binds only to Intel Atom E38XX (Baytrail-I) virtual serial
ports on the Dell Edge 300x GW. These updates are being carried in the
linux-oem (4.15.y) kernel for more than 2 years without any regressions.

[Note]
This driver has been submitted upstream and is under review. This issue has
been identified as a regression in 4.15 and multiple solutions are being
explored. Meanwhile, to support customer and maintain release schedule,
this driver needs to be in Ubuntu 4.15 based kernels.
More info:
https://marc.info/?t=152455871600007&r=1&w=2

linux-oem buglink: http://bugs.launchpad.net/bugs/1690362

Tags: bionic
description: updated
Revision history for this message
Ubuntu Kernel Bot (ubuntu-kernel-bot) wrote : Missing required logs.

This bug is missing log files that will aid in diagnosing the problem. While running an Ubuntu kernel (not a mainline or third-party kernel) please enter the following command in a terminal window:

apport-collect 1864147

and then change the status of the bug to 'Confirmed'.

If, due to the nature of the issue you have encountered, you are unable to run this command, please add a comment stating that fact and change the bug status to 'Confirmed'.

This change has been made by an automated script, maintained by the Ubuntu Kernel Team.

Changed in linux (Ubuntu):
status: New → Incomplete
Changed in linux (Ubuntu Bionic):
status: New → Incomplete
tags: added: bionic
Changed in linux (Ubuntu Bionic):
status: Incomplete → Confirmed
importance: Undecided → High
Changed in linux (Ubuntu):
status: Incomplete → Confirmed
importance: Undecided → High
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