On Thu, Dec 05, 2024 at 06:30:33AM -0800, Guenter Roeck wrote:
> Commit 7c7e6c8924e7 ("tty: serial: handle HAS_IOPORT dependencies")
> triggers warning backtraces on a number of platforms which don't support
> IO ports.
>
> WARNING: CPU: 0 PID: 0 at drivers/tty/serial/8250/8250_port.c:470 serial8250_set_defaults+0x148/0x1d8
> Unsupported UART type 0
>
> The problem is seen because serial8250_set_defaults() is called for
> all members of the serial8250_ports[] array even if that array is
> not initialized.
>
> Work around the problem by only displaying the warning if the port
> type is not 0 (UPIO_PORT) or if iobase is set for the port.
>
> Fixes: 7c7e6c8924e7 ("tty: serial: handle HAS_IOPORT dependencies")
> Acked-by: Arnd Bergmann <arnd@xxxxxxxx>
> Cc: Niklas Schnelle <schnelle@xxxxxxxxxxxxx>
> Signed-off-by: Guenter Roeck <linux@xxxxxxxxxxxx>
> ---
> A complete fix will require a sequence of patches, which will have to be
> tested thoroughly and is thus not 6.13 material. This patch doesn't fix
> the underlying problem, but it is good enough for 6.13, or at least not
> worse than 6.12, while at the same time avoiding the warning backtrace.
This works on OpenRISC where I was seeing the issue. Has someone comitted to
work on the root cause?
Tested-by: Stafford Horne <shorne@xxxxxxxxx>
> drivers/tty/serial/8250/8250_port.c | 3 ++-
> 1 file changed, 2 insertions(+), 1 deletion(-)
>
> diff --git a/drivers/tty/serial/8250/8250_port.c b/drivers/tty/serial/8250/8250_port.c
> index 4d63d80e78a9..649e74e9b52f 100644
> --- a/drivers/tty/serial/8250/8250_port.c
> +++ b/drivers/tty/serial/8250/8250_port.c
> @@ -467,7 +467,8 @@ static void set_io_from_upio(struct uart_port *p)
> break;
> #endif
> default:
> - WARN(1, "Unsupported UART type %x\n", p->iotype);
> + WARN(p->iotype != UPIO_PORT || p->iobase,
> + "Unsupported UART type %x\n", p->iotype);
> p->serial_in = no_serial_in;
> p->serial_out = no_serial_out;
> }
> --
> 2.45.2
>
>
