Hello dear linux-serial developers,
I'v been struggling for some time to get brainboxes multiport serial
card working under 4.14 kernel.. it's working fine for me under 4.4
(just using some setserial magic), but I need to switch to newer kernel.
Under 4.14, when I try to setup the card, system either hangs, or just
spits backtrace and hangs when I try to use some of the configured ports
After some googling, I noticed some reports of multiport serial cards problem
between 4.8 and 4.9 (without resolution), so I tested it, and really, 4.8
works fine, 4.9 always hangs during setserial setup (I'm not 100% sure it's
the same problem I have in 4.14 though).
I've bisected it to
commit b3b57646186400d4f54652ab7bbf55f5764d9467
Author: Rob Herring <robh@xxxxxxxxxx>
Date: Mon Aug 22 17:39:09 2016 -0500
tty: serial_core: convert uart_open to use tty_port_open
tty_port_open handles much of the common parts of tty opening. Convert
uart_open to use it and move the serial_core specific parts into
tty_port.activate function. This will be needed to use tty_port functions
directly from in kernel clients.
The tricky part is uart_port_startup can return positive values to allow
setserial to configure the port. We now return the positive value to
tty_port_open so that the tty is not marked as initialized and then set the
return value in uart_open to 0.
Cc: Peter Hurley <peter@xxxxxxxxxxxxxxxxxx>
Signed-off-by: Rob Herring <robh@xxxxxxxxxx>
Acked-by: Alan Cox <alan@xxxxxxxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
before this patch, it works, after it, it doesn't. My question is, does
somebody remember some issues being fixed after this one?
It's problematic to revert even with 4.9, and even worse with 4.14, so
before I try digging deeper into it, I thougt I'd just try my luck asking
here :)
I'd be very gratefull for any hints
cheers
BR
nik
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