diff --git a/Documentation/kernel-parameters.txt b/Documentation/kernel-parameters.txt
index 61ab162..1edb048 100644
--- a/Documentation/kernel-parameters.txt
+++ b/Documentation/kernel-parameters.txt
@@ -335,6 +335,22 @@ bytes respectively. Such letter suffixes can also be entirely omitted.
 			to assume that this machine's pmtimer latches its value
 			and always returns good values.
 
+	acpi.rev_override= [HW,ACPI]
+			Export 5 as the supported ACPI REV
+			Format: { "0" | "1" } (0 = DMI-based quirks,
+					       1 = force-enabled)
+			Up to and including Linux v4.1, the BIOS was told which
+			ACPI revision the ACPICA subsystem in Linux actually
+			supports (which was 5 at the time); from v4.2 on, this
+			value will be set statically to 2 to match the behavior
+			of other ACPI implementations. As some BIOS may operate
+			differently depending on which value _REV is set to, this
+			parameter offers the capability to specify that the
+			previously used value 5 is to be exported to the firmware.
+			Note that such changes in the behavior of the BIOS may
+			only be visible after cold booting the system with this
+			parameter _twice_.
+
 	acpi_sci=	[HW,ACPI] ACPI System Control Interrupt trigger mode
 			Format: { level | edge | high | low }
 
diff --git a/drivers/acpi/Kconfig b/drivers/acpi/Kconfig
index ab2cbb5..a5272c2 100644
--- a/drivers/acpi/Kconfig
+++ b/drivers/acpi/Kconfig
@@ -430,4 +430,24 @@ config XPOWER_PMIC_OPREGION
 
 endif
 
+config ACPI_REV_OVERRIDE_DELL_XPS_13_2015
+	bool "Dell XPS 13 (2015) quirk to force HDA sound"
+	depends on X86 && SND_HDA
+	default y
+	help
+	  Based on what ACPI exports as the supported revision to the firmware,
+	  Dell XPS 13 (2015) configures its audio device to either work in HDA
+	  mode or in I2S mode, where the former is supposed to be used on Linux
+	  until the latter is fully supported (in the kernel as well as in user
+	  space).
+
+	  This option enables a DMI-based quirk for the above Dell machine (so
+	  that HDA audio is exposed by the platform  firmware to the kernel) and
+	  makes it possible to force the kernel to return "5" as the supported
+	  ACPI revision via the "acpi_rev_override" command line switch (when
+	  using that switch it may be necessary to carry out a cold reboot
+	  _twice_ in a row to make it take effect on the firmware).
+
+	  If in doubt, say Y.
+
 endif	# ACPI
diff --git a/drivers/acpi/blacklist.c b/drivers/acpi/blacklist.c
index 1d17919..ed55ad7 100644
--- a/drivers/acpi/blacklist.c
+++ b/drivers/acpi/blacklist.c
@@ -162,6 +162,15 @@ static int __init dmi_disable_osi_win8(const struct dmi_system_id *d)
 	acpi_osi_setup("!Windows 2012");
 	return 0;
 }
+#ifdef CONFIG_ACPI_REV_OVERRIDE_DELL_XPS_13_2015
+static int __init dmi_enable_rev_override(const struct dmi_system_id *d)
+{
+	printk(KERN_NOTICE PREFIX "DMI detected: %s (force ACPI _REV to 5)\n",
+	       d->ident);
+	acpi_rev_override = true;
+	return 0;
+}
+#endif
 
 static struct dmi_system_id acpi_osi_dmi_table[] __initdata = {
 	{
@@ -325,6 +334,23 @@ static struct dmi_system_id acpi_osi_dmi_table[] __initdata = {
 		     DMI_MATCH(DMI_PRODUCT_NAME, "1015PX"),
 		},
 	},
+
+#ifdef CONFIG_ACPI_REV_OVERRIDE_DELL_XPS_13_2015
+	/*
+	 * DELL XPS 13 (2015) switches sound between HDA and I2S
+	 * depending on the ACPI _REV callback. If userspace supports
+	 * I2S sufficiently (or if you do not care about sound), you
+	 * can safely disable this quirk.
+	 */
+	{
+	 .callback = dmi_enable_rev_override,
+	 .ident = "DELL XPS 13 (2015)",
+	 .matches = {
+		      DMI_MATCH(DMI_SYS_VENDOR, "Dell Inc."),
+		      DMI_MATCH(DMI_PRODUCT_NAME, "XPS 13 9343"),
+		},
+	},
+#endif
 	{}
 };
 
diff --git a/drivers/acpi/internal.h b/drivers/acpi/internal.h
index ba4a61e..fc8db23 100644
--- a/drivers/acpi/internal.h
+++ b/drivers/acpi/internal.h
@@ -23,6 +23,7 @@
 
 #define PREFIX "ACPI: "
 
+extern bool acpi_rev_override;
 acpi_status acpi_os_initialize1(void);
 int init_acpi_device_notify(void);
 int acpi_scan_init(void);
diff --git a/drivers/acpi/osl.c b/drivers/acpi/osl.c
index 7ccba39..4d020d0 100644
--- a/drivers/acpi/osl.c
+++ b/drivers/acpi/osl.c
@@ -534,6 +534,9 @@ acpi_os_get_physical_address(void *virt, acpi_physical_address * phys)
 }
 #endif
 
+bool acpi_rev_override;
+module_param_named(rev_override, acpi_rev_override, bool, 0);
+
 #define ACPI_MAX_OVERRIDE_LEN 100
 
 static char acpi_os_name[ACPI_MAX_OVERRIDE_LEN];
@@ -552,6 +555,11 @@ acpi_os_predefined_override(const struct acpi_predefined_names *init_val,
 		*new_val = acpi_os_name;
 	}
 
+	if (!memcmp(init_val->name, "_REV", 4) && acpi_rev_override) {
+		printk(KERN_INFO PREFIX "Overriding _REV return value to 5\n");
+		*new_val = (char *)5;
+	}
+
 	return AE_OK;
 }
 
