Update Linux to v5.4.2

Change-Id: Idf6911045d9d382da2cfe01b1edff026404ac8fd
diff --git a/drivers/acpi/spcr.c b/drivers/acpi/spcr.c
index 9d52743..d73b453 100644
--- a/drivers/acpi/spcr.c
+++ b/drivers/acpi/spcr.c
@@ -1,12 +1,8 @@
+// SPDX-License-Identifier: GPL-2.0-only
 /*
  * Copyright (c) 2012, Intel Corporation
  * Copyright (c) 2015, Red Hat, Inc.
  * Copyright (c) 2015, 2016 Linaro Ltd.
- *
- * This program is free software; you can redistribute it and/or modify
- * it under the terms of the GNU General Public License version 2 as
- * published by the Free Software Foundation.
- *
  */
 
 #define pr_fmt(fmt) "ACPI: SPCR: " fmt
@@ -28,7 +24,7 @@
 
 /*
  * Some Qualcomm Datacenter Technologies SoCs have a defective UART BUSY bit.
- * Detect them by examining the OEM fields in the SPCR header, similiar to PCI
+ * Detect them by examining the OEM fields in the SPCR header, similar to PCI
  * quirk detection in pci_mcfg.c.
  */
 static bool qdf2400_erratum_44_present(struct acpi_table_header *h)
@@ -148,6 +144,13 @@
 	}
 
 	switch (table->baud_rate) {
+	case 0:
+		/*
+		 * SPCR 1.04 defines 0 as a preconfigured state of UART.
+		 * Assume firmware or bootloader configures console correctly.
+		 */
+		baud_rate = 0;
+		break;
 	case 3:
 		baud_rate = 9600;
 		break;
@@ -196,6 +199,10 @@
 		 * UART so don't attempt to change to the baud rate state
 		 * in the table because driver cannot calculate the dividers
 		 */
+		baud_rate = 0;
+	}
+
+	if (!baud_rate) {
 		snprintf(opts, sizeof(opts), "%s,%s,0x%llx", uart, iotype,
 			 table->serial_port.address);
 	} else {