DRM/i915: Add QUIRK_INVERT_BRIGHTNESS for NCR machines.

commit 5f85f176 upstream.

NCR machines with LVDS panels using Intel chipsets need to have the
QUIRK_INVERT_BRIGHTNESS bit set.
Unfortunately NCR doesn't set a meaningful subvendor/subdevice ID,
therefore we add a DMI dependent quirk list.
Signed-off-by: Egbert Eich <eich@suse.de>
[danvet: fixup whitespace fail.]
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>
Acked-by: Jani Nikula <jani.nikula@intel.com>
[bwh: Backported to 3.2:
 - Adjust context
 - Add #include <linux/dmi.h>]
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>

drivers/gpu/drm/i915/intel_display.c

@@ -25,6 +25,7 @@
  */
 
 #include <linux/cpufreq.h>
+#include <linux/dmi.h>
 #include <linux/module.h>
 #include <linux/input.h>
 #include <linux/i2c.h>
@@ -8848,6 +8849,34 @@ struct intel_quirk {
 	void (*hook)(struct drm_device *dev);
 };
 
+/* For systems that don't have a meaningful PCI subdevice/subvendor ID */
+struct intel_dmi_quirk {
+	void (*hook)(struct drm_device *dev);
+	const struct dmi_system_id (*dmi_id_list)[];
+};
+
+static int intel_dmi_reverse_brightness(const struct dmi_system_id *id)
+{
+	DRM_INFO("Backlight polarity reversed on %s\n", id->ident);
+	return 1;
+}
+
+static const struct intel_dmi_quirk intel_dmi_quirks[] = {
+	{
+		.dmi_id_list = &(const struct dmi_system_id[]) {
+			{
+				.callback = intel_dmi_reverse_brightness,
+				.ident = "NCR Corporation",
+				.matches = {DMI_MATCH(DMI_SYS_VENDOR, "NCR Corporation"),
+					    DMI_MATCH(DMI_PRODUCT_NAME, ""),
+				},
+			},
+			{ }  /* terminating entry */
+		},
+		.hook = quirk_invert_brightness,
+	},
+};
+
 struct intel_quirk intel_quirks[] = {
 	/* HP Compaq 2730p needs pipe A force quirk (LP: #291555) */
 	{ 0x2a42, 0x103c, 0x30eb, quirk_pipea_force },
@@ -8895,6 +8924,10 @@ static void intel_init_quirks(struct drm_device *dev)
 		     q->subsystem_device == PCI_ANY_ID))
 			q->hook(dev);
 	}
+	for (i = 0; i < ARRAY_SIZE(intel_dmi_quirks); i++) {
+		if (dmi_check_system(*intel_dmi_quirks[i].dmi_id_list) != 0)
+			intel_dmi_quirks[i].hook(dev);
+	}
 }
 
 /* Disable the VGA plane that we never use */