===================================================================
@@ -162,6 +162,15 @@ static int __init dmi_disable_osi_win8(c
acpi_osi_setup("!Windows 2012");
return 0;
}
+#ifdef CONFIG_ACPI_REV_OVERRIDE_POSSIBLE
+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_setup(NULL);
+ 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
DMI_MATCH(DMI_PRODUCT_NAME, "1015PX"),
},
},
+
+#ifdef CONFIG_ACPI_REV_OVERRIDE_POSSIBLE
+ /*
+ * 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
{}
};
===================================================================
@@ -23,6 +23,10 @@
#define PREFIX "ACPI: "
+#ifdef CONFIG_ACPI_REV_OVERRIDE_POSSIBLE
+int __init acpi_rev_override_setup(char *str);
+#endif
+
acpi_status acpi_os_initialize1(void);
int init_acpi_device_notify(void);
int acpi_scan_init(void);
===================================================================
@@ -534,6 +534,19 @@ acpi_os_get_physical_address(void *virt,
}
#endif
+#ifdef CONFIG_ACPI_REV_OVERRIDE_POSSIBLE
+static bool acpi_rev_override;
+
+int __init acpi_rev_override_setup(char *str)
+{
+ acpi_rev_override = true;
+ return 1;
+}
+__setup("acpi_rev_override", acpi_rev_override_setup);
+#else
+#define acpi_rev_override false
+#endif
+
#define ACPI_MAX_OVERRIDE_LEN 100
static char acpi_os_name[ACPI_MAX_OVERRIDE_LEN];
@@ -552,6 +565,11 @@ acpi_os_predefined_override(const struct
*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;
}
===================================================================
@@ -428,6 +428,28 @@ config XPOWER_PMIC_OPREGION
help
This config adds ACPI operation region support for XPower AXP288 PMIC.
++config ACPI_REV_OVERRIDE_POSSIBLE
+ bool "Allow supported ACPI revision to be overriden"
+ depends on X86
+ default y
+ help
+ The platform firmware on some systems expects Linux to return "5" as
+ the supported ACPI revision which makes it expose system configuration
+ information in a special way.
+
+ For example, based on what ACPI exports as the supported revision,
+ 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).
+
endif
endif # ACPI