From patchwork Fri Apr 20 03:29:47 2018 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit Subject: ACPI / scan: Fix regression related to X-Gene UARTs From: Mark Salter X-Patchwork-Id: 10351797 Message-Id: <20180420032947.23023-1-msalter@redhat.com> To: =?UTF-8?q?Fr=C3=A9d=C3=A9ric=20Danis?= Cc: "Rafael J . Wysocki" , linux-acpi@vger.kernel.org, linux-kernel@vger.kernel.org Date: Thu, 19 Apr 2018 23:29:47 -0400 Commit e361d1f85855 ("ACPI / scan: Fix enumeration for special UART devices") caused a regression with some X-Gene based platforms (Mustang and M400) with invalid DSDT. The DSDT makes it appear that the UART device is also a slave device attached to itself. With the above commit the UART won't be enumerated by ACPI scan (slave serial devices shouldn't be). So check for X-Gene UART device and skip slace device check on it. Signed-off-by: Mark Salter --- drivers/acpi/scan.c | 8 ++++++++ 1 file changed, 8 insertions(+) diff --git a/drivers/acpi/scan.c b/drivers/acpi/scan.c index cc234e6a6297..1dcdd0122862 100644 --- a/drivers/acpi/scan.c +++ b/drivers/acpi/scan.c @@ -1551,6 +1551,14 @@ static bool acpi_device_enumeration_by_parent(struct acpi_device *device) fwnode_property_present(&device->fwnode, "baud"))) return true; + /* + * Firmware on some arm64 X-Gene platforms will make the UART + * device appear as both a UART and a slave of that UART. Just + * bail out here for X-Gene UARTs. + */ + if (!strcmp(acpi_device_hid(device), "APMC0D08")) + return false; + INIT_LIST_HEAD(&resource_list); acpi_dev_get_resources(device, &resource_list, acpi_check_serial_bus_slave,