On Wed, Mar 8, 2023, at 12:24, Niklas Schnelle wrote:
> On Thu, 2023-01-05 at 09:03 +0100, Arnd Bergmann wrote:
>
> Yes that makes sense, it's clearly not correct to put the default case
> inside CONFIG_SERIAL_8250_RT288X. What do you think about going with
> something like:
>
> @@ -519,9 +534,14 @@ static void set_io_from_upio(struct uart_port *p)
> #endif
>
> default:
> +#ifdef CONFIG_HAS_IOPORT
> p->serial_in = io_serial_in;
> p->serial_out = io_serial_out;
> break;
> +#else
> + WARN(1, "Unsupported UART type \"io\"\n");
> + return;
> +#endif
> }
I think we have to ensure that ->serial_in() always points
to some function that doesn't immediately panic, though that
could be an empty dummy like
default:
p->serial_in = IS_ENABLED(CONFIG_HAS_IOPORT) ?
io_serial_in : no_serial_in;
p->serial_out = IS_ENABLED(CONFIG_HAS_IOPORT) ?
io_serial_out : no_serial_out;
Ideally we'd make mem_serial_in() the default function
and only use io_serial_in() when UPIO_PORT is selected,
but that still causes a NULL pointer dereference when
a platform initializes a 8250 like
static struct plat_serial8250_port serial_platform_data[] = {
{
.iobase = 0x3f8, /* NULL pointer */
.irq = IRQ_ISA_UART,
.uartclk = 1843200,
/* default .iotype = UPIO_PORT, */
},
so I think an empty function plus a warning is best here.
> I've pushed a version with the above change rebased on v6.3-rc1 to my
> git.kernel.org repository and will do some more testing before I can
> hopefully send this out for review and make some progress on this.
> Meanwhile the original problem is now the only thing preventing clean
> Werror builds on clang for s390 as far as I understand.
Thanks a lot! Let's hope we can manage to get this merged at last.
Arnd
