Check the 'Register Bit Width' field of the ACPI Generic Address Structure that specifies the address of the UART registers to decide if the driver should use "mmio32" access instead of "mmio". If the driver is other than 16550 the access with is defined by the Interface Type field of the SPCR table. For discussion: https://lkml.kernel.org/r/7fa523de-3fbb-1566-f521-927143f73d1e@xxxxxxxxxx Signed-off-by: Aleksey Makarov <aleksey.makarov@xxxxxxxxxx> Signed-off-by: Graeme Gregory <graeme.gregory@xxxxxxxxxx> Reported-by: Heyi Guo <heyi.guo@xxxxxxxxxx> --- drivers/acpi/spcr.c | 4 ++++ 1 file changed, 4 insertions(+) diff --git a/drivers/acpi/spcr.c b/drivers/acpi/spcr.c index e8d7bc7..6c6710b 100644 --- a/drivers/acpi/spcr.c +++ b/drivers/acpi/spcr.c @@ -70,6 +70,10 @@ int __init parse_spcr(bool earlycon) break; case ACPI_DBG2_16550_COMPATIBLE: case ACPI_DBG2_16550_SUBSET: + if (table->serial_port.space_id == + ACPI_ADR_SPACE_SYSTEM_MEMORY && + table->serial_port.bit_width == 32) + iotype = "mmio32"; uart = "uart"; break; default: -- 2.10.2 -- To unsubscribe from this list: send the line "unsubscribe linux-serial" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
