drm/vc4: Add specific compatible strings for Cygnus.

Cygnus has V3D 2.6 instead of 2.1, and doesn't use the VC4 display
modules.  The V3D can be uniquely identified by the IDENT[01]
registers, and there's nothing to key off of for the display change
other than the lack of DT nodes for the display components, but it's
convention to have new compatible strings anyway.

Signed-off-by: Eric Anholt <eric@anholt.net>
Acked-by: Rob Herring <robh@kernel.org>
Link: http://patchwork.freedesktop.org/patch/msgid/20170428224223.21904-3-eric@anholt.net
diff --git a/Documentation/devicetree/bindings/display/brcm,bcm-vc4.txt b/Documentation/devicetree/bindings/display/brcm,bcm-vc4.txt
index bc1756f..284e2b1 100644
--- a/Documentation/devicetree/bindings/display/brcm,bcm-vc4.txt
+++ b/Documentation/devicetree/bindings/display/brcm,bcm-vc4.txt
@@ -5,7 +5,7 @@
 display planes.
 
 Required properties for VC4:
-- compatible:	Should be "brcm,bcm2835-vc4"
+- compatible:	Should be "brcm,bcm2835-vc4" or "brcm,cygnus-vc4"
 
 Required properties for Pixel Valve:
 - compatible:	Should be one of "brcm,bcm2835-pixelvalve0",
@@ -54,7 +54,7 @@
 		  See bindings/interrupt-controller/brcm,bcm2835-armctrl-ic.txt
 
 Required properties for V3D:
-- compatible:	Should be "brcm,bcm2835-v3d"
+- compatible:	Should be "brcm,bcm2835-v3d" or "brcm,cygnus-v3d"
 - reg:		Physical base address and length of the V3D's registers
 - interrupts:	The interrupt number
 		  See bindings/interrupt-controller/brcm,bcm2835-armctrl-ic.txt
diff --git a/drivers/gpu/drm/vc4/vc4_drv.c b/drivers/gpu/drm/vc4/vc4_drv.c
index 92fb9a4..754ce76 100644
--- a/drivers/gpu/drm/vc4/vc4_drv.c
+++ b/drivers/gpu/drm/vc4/vc4_drv.c
@@ -335,6 +335,7 @@ static int vc4_platform_drm_remove(struct platform_device *pdev)
 
 static const struct of_device_id vc4_of_match[] = {
 	{ .compatible = "brcm,bcm2835-vc4", },
+	{ .compatible = "brcm,cygnus-vc4", },
 	{},
 };
 MODULE_DEVICE_TABLE(of, vc4_of_match);
diff --git a/drivers/gpu/drm/vc4/vc4_v3d.c b/drivers/gpu/drm/vc4/vc4_v3d.c
index 7500820..c53afec 100644
--- a/drivers/gpu/drm/vc4/vc4_v3d.c
+++ b/drivers/gpu/drm/vc4/vc4_v3d.c
@@ -450,6 +450,7 @@ static int vc4_v3d_dev_remove(struct platform_device *pdev)
 
 static const struct of_device_id vc4_v3d_dt_match[] = {
 	{ .compatible = "brcm,bcm2835-v3d" },
+	{ .compatible = "brcm,cygnus-v3d" },
 	{ .compatible = "brcm,vc4-v3d" },
 	{}
 };