Update: the problem reproduces also on x86-64 with 8250 driver. root@madhouse:~# uname -a Linux madhouse 4.12.0-rc2+ #2 SMP Thu May 25 12:08:00 MSK 2017 x86_64 x86_64 x86_64 GNU/Linux root@madhouse:~# time stty -F /dev/ttyS0 speed 9600 baud; line = 0; -brkint -imaxbel
real 0m0.010s user 0m0.011s sys 0m0.000s root@madhouse:~# cat blah > /dev/ttyS0 ^C root@madhouse:~# time stty -F /dev/ttyS0 speed 9600 baud; line = 0; -brkint -imaxbel real 0m30.732s user 0m0.011s sys 0m0.002s root@madhouse:~# -- Best regards Dmitry Artamonow
