tty: serial: meson: fix hard LOCKUP on crtscts mode

There might be hard lockup if we set crtscts mode on port without RTS/CTS configured:

# stty -F /dev/ttyAML6 crtscts; echo 1 > /dev/ttyAML6; echo 2 > /dev/ttyAML6
[   95.890386] rcu: INFO: rcu_preempt detected stalls on CPUs/tasks:
[   95.890857] rcu:     3-...0: (201 ticks this GP) idle=e33c/1/0x4000000000000000 softirq=5844/5846 fqs=4984
[   95.900212] rcu:     (detected by 2, t=21016 jiffies, g=7753, q=296 ncpus=4)
[   95.906972] Task dump for CPU 3:
[   95.910178] task:bash            state:R  running task     stack:0     pid:205   ppid:1      flags:0x00000202
[   95.920059] Call trace:
[   95.922485]  __switch_to+0xe4/0x168
[   95.925951]  0xffffff8003477508
[   95.974379] watchdog: Watchdog detected hard LOCKUP on cpu 3
[   95.974424] Modules linked in: 88x2cs(O) rtc_meson_vrtc

Possible solution would be to not allow to setup crtscts on such port.

Tested on S905X3 based board.

Fixes: ff7693d079e5 ("ARM: meson: serial: add MesonX SoC on-chip uart driver")
Cc: [email protected]
Signed-off-by: Pavel Krasavin <[email protected]>
Reviewed-by: Neil Armstrong <[email protected]>
Reviewed-by: Dmitry Rokosov <[email protected]>

v6: stable tag added
v5: https://lore.kernel.org/lkml/[email protected]/
added missed Reviewed-by tags, Fixes tag added according to Dmitry and Neil notes
v4: https://lore.kernel.org/lkml/[email protected]/
More correct patch subject according to Jiri's note
v3: https://lore.kernel.org/lkml/[email protected]/
"From:" line added to the mail
v2: https://lore.kernel.org/lkml/[email protected]/
braces for single statement removed according to Dmitry's note
v1: https://lore.kernel.org/lkml/[email protected]/
Link: https://lore.kernel.org/r/[email protected]

Signed-off-by: Greg Kroah-Hartman <[email protected]>

0 files changed, 0 insertions, 0 deletions