From bafa91b945ac77e2e1d000e356ca819bd5f87460 Mon Sep 17 00:00:00 2001
From: Christian Poessinger <christian@poessinger.com>
Date: Mon, 8 Jun 2020 22:45:04 +0200
Subject: console: T2529: migrate from ttyUSB device to new device in
 /dev/serial/by-bus

During testing it was discovered that there is a well known problem (we had for
ethernet interfaces) also in the serial port world. They will be enumerated and
mapped to /dev/ttyUSBxxx differently from boot to boot. This is especially
painful on my development APU4 board which also has a Sierra Wireless MC7710
LTE module installed.

The serial port will toggle between ttyUSB2 and ttyUSB5 depending on the
amount of serial port extenders attached (FT4232H).

The shipped udev rule (/usr/lib/udev/rules.d/60-serial.rules) partly solves
this by enumerating the devices into /dev/serial/by-id folder with their name
and serial number - it's a very good idea but I've found that not all of the
FT4232H dongles have a serial number programmed - this leads to the situation
that when you plug in two cables with both having serial number 0 - only one
device symlink will appear - the previous one is always overwritten by the
latter one.

Derive /usr/lib/udev/rules.d/60-serial.rules and create a /dev/serial/by-bus
directory and group devices by attached USB root port.
---
 interface-definitions/system-console.xml.in | 14 +++++++++-----
 1 file changed, 9 insertions(+), 5 deletions(-)

(limited to 'interface-definitions')

diff --git a/interface-definitions/system-console.xml.in b/interface-definitions/system-console.xml.in
index ccaaa51b2..71e63d0cb 100644
--- a/interface-definitions/system-console.xml.in
+++ b/interface-definitions/system-console.xml.in
@@ -11,20 +11,24 @@
           <tagNode name="device">
             <properties>
               <help>Serial console device name</help>
+              <completionHelp>
+                <script>ls -1 /dev | grep -e ttyS -e hvc</script>
+                <script>if [ -d /dev/serial/by-bus ]; then ls -1 /dev/serial/by-bus; fi</script>
+              </completionHelp>
               <valueHelp>
                 <format>ttySN</format>
-                <description>Serial device name</description>
+                <description>TTY device name, regular serial port</description>
               </valueHelp>
               <valueHelp>
-                <format>ttyUSBX</format>
-                <description>USB Serial device name</description>
+                <format>usbNbXpY</format>
+                <description>TTY device name, USB based</description>
               </valueHelp>
               <valueHelp>
-                <format>hvc0</format>
+                <format>hvcN</format>
                 <description>Xen console</description>
               </valueHelp>
               <constraint>
-                  <regex>^(ttyS|ttyUSB|hvc)[0-9]+$</regex>
+                  <regex>^(ttyS[0-9]+|hvc[0-9]+|usb[0-9]+b.*)$</regex>
               </constraint>
             </properties>
             <children>
-- 
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