On 21 April 2017 at 19:18, Ard Biesheuvel <ard.biesheuvel@xxxxxxxxxx> wrote:
> Commit fa01e2ca9f53 ("serial: 8250: Integrate Fintek into 8250_base")
> modified the probing logic for PNP0501 devices, to remove a collision
> between the generic 16550A driver and the Fintek driver, which reused
> the same ACPI _HID.
>
> The Fintek device probe is now incorporated into the common 8250 probe
> path, and gets called for all discovered 16550A compatible devices,
> including ones that are MMIO mapped rather than IO mapped. However,
> the Fintek driver assumes the port base is a I/O address, and proceeds
> to probe some arbitrary offsets above it.
>
> This is generally a wrong thing to do, but on ARM systems (having no
> native port I/O), this may result in faulting accesses of completely
> unrelated MMIO regions in the PCI I/O space. Given that this is at
> serial probe time, this results in hard to diagnose crashes at boot.
>
> So let's restrict the Fintek probe to devices that we know are using
> port I/O in the first place.
>
> Fixes: fa01e2ca9f53 ("serial: 8250: Integrate Fintek into 8250_base")
> Suggested-by: Arnd Bergmann <arnd@xxxxxxxx>
> Signed-off-by: Ard Biesheuvel <ard.biesheuvel@xxxxxxxxxx>
> ---
>
> May we have a cc stable for this one please? Thanks.
>
> drivers/tty/serial/8250/8250_port.c | 2 +-
> 1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/drivers/tty/serial/8250/8250_port.c b/drivers/tty/serial/8250/8250_port.c
> index 6119516ef5fc..4c26d15ad7d9 100644
> --- a/drivers/tty/serial/8250/8250_port.c
> +++ b/drivers/tty/serial/8250/8250_port.c
> @@ -1337,7 +1337,7 @@ static void autoconfig(struct uart_8250_port *up)
> /*
> * Check if the device is a Fintek F81216A
> */
> - if (port->type == PORT_16550A)
> + if (port->type == PORT_16550A && port->iotype == UPIO_PORT)
> fintek_8250_probe(up);
>
> if (up->capabilities != old_capabilities) {
> --
> 2.9.3
>
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