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From 176c6c76841d9600f1309742dd7af40a69f6f91b Mon Sep 17 00:00:00 2001
From: Mark Salter <msalter@redhat.com>
Date: Thu, 10 May 2018 17:38:44 -0400
Subject: [PATCH] aarch64: acpi scan: Fix regression related to X-Gene UARTs
Message-id: <20180510173844.29580-4-msalter@redhat.com>
Patchwork-id: 214381
O-Subject: [RHEL-8 BZ1519554 3/3] aarch64: acpi scan: Fix regression related to X-Gene UARTs
Bugzilla: 1519554
RH-Acked-by: Al Stone <astone@redhat.com>
RH-Acked-by: Tony Camuso <tcamuso@redhat.com>
Bugzilla: https://bugzilla.redhat.com/show_bug.cgi?id=1519554
Brew: https://brewweb.engineering.redhat.com/brew/taskinfo?taskID=16144520
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.
Upstream Status: RHEL only
Signed-off-by: Mark Salter <msalter@redhat.com>
Signed-off-by: Herton R. Krzesinski <herton@redhat.com>
---
drivers/acpi/scan.c | 9 +++++++++
1 file changed, 9 insertions(+)
diff --git a/drivers/acpi/scan.c b/drivers/acpi/scan.c
index 6d3448895382..221255007dc8 100644
--- a/drivers/acpi/scan.c
+++ b/drivers/acpi/scan.c
@@ -1563,6 +1563,15 @@ static bool acpi_device_enumeration_by_parent(struct acpi_device *device)
if (!acpi_match_device_ids(device, i2c_multi_instantiate_ids))
return false;
+ /*
+ * 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 (IS_ENABLED(CONFIG_ARM64) &&
+ !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,
--
2.26.2
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