[Pkg-electronics-devel] Bug#990863: Bug#990863: libserialport0: libserialport tries to use termiox on bullseye, and fails to open serial ports

[Jonathan McDowell]

On Fri, Jul 09, 2021 at 05:55:52PM +0100, Tim Small wrote:
> Package: libserialport0
> Version: 0.1.1-3+b1
> Severity: important
> Tags: upstream patch
> X-Debbugs-Cc: tim at seoss.co.uk
> 
> Serial port open seems to fail on bullseye.  Strace output follows:
> 
> 1512868 openat(AT_FDCWD, "/dev/ttyACM0", O_RDWR|O_NOCTTY|O_NONBLOCK) = 9
> 1512868 ioctl(9, TCGETS, {B9600 opost isig icanon echo ...}) = 0
> 1512868 ioctl(9, TIOCMGET, [TIOCM_DTR|TIOCM_RTS|TIOCM_CTS]) = 0
> 1512868 ioctl(9, TCGETX, 0x55cd7cc80df0) = -1 ENOTTY (Inappropriate ioctl for device)
> 1512868 close(9)                        = 0
> 1512868 write(2, "sr: ", 4)             = 4
> 1512868 write(2, "serial-libsp: Error opening port"..., 71) = 71
> 1512868 write(2, "No devices found.\n", 18) = 18
> 
> Applying upstream commit 6f9b03e597ea fixes the issue.  I tested this
> with:
> 
> /usr/local/bin/sigrok-cli --driver=rdtech-tc:conn=/dev/ttyACM0 --continuous
> 
> Patch here:
> 
> https://github.com/sigrokproject/libserialport/commit/6f9b03e597ea7200eb616a4e410add3dd1690cb1
> 
> I suspect that libserialport0 will fail to open all serial ports on
> bullseye without this fix, so this bug may unfortunately be RC?

It looks like the kernel broke this in the v5.10.37 update
(eef2158b0c44baa8cd9855091b1d99a35e16afdb), which hit
unstable towards the end of May. Not clear why this was backported to
the stable tree but I guess fixing libserialport is going to be the
easier solution.

J.

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