drm/vc4: Add DT parameters to control CMA usage

Example: dtoverlay=vc4-kms-v3d,cma-128

See: #1431

Signed-off-by: Phil Elwell <[email protected]>

Author: Phil Elwell

arch/arm/boot/dts/overlays/README

@@ -1023,8 +1023,12 @@ Name:   vc4-kms-v3d
 Info:   Enable Eric Anholt's DRM VC4 HDMI/HVS/V3D driver. Running startx or
         booting to GUI while this overlay is in use will cause interesting
         lockups.
-Load:   dtoverlay=vc4-kms-v3d
-Params: <None>
+Load:   dtoverlay=vc4-kms-v3d,<param>
+Params: cma-256                 CMA is 256MB, 256MB-aligned (needs 1GB)
+        cma-192                 CMA is 192MB, 256MB-aligned (needs 1GB)
+        cma-128                 CMA is 128MB, 128MB-aligned
+        cma-96                  CMA is 96MB, 128MB-aligned
+        cma-64                  CMA is 64MB, 64MB-aligned
 
 
 Name:   vga666

arch/arm/boot/dts/overlays/vc4-kms-v3d-overlay.dts

@@ -94,4 +94,40 @@
 			bootargs = "cma=256M@256M";
 		};
 	};
+
+	fragment@5 {
+		target-path = "/chosen";
+		__dormant__ {
+			bootargs = "cma=192M@256M";
+		};
+	};
+
+	fragment@6 {
+		target-path = "/chosen";
+		__dormant__ {
+			bootargs = "cma=128M@128M";
+		};
+	};
+
+	fragment@7 {
+		target-path = "/chosen";
+		__dormant__ {
+			bootargs = "cma=96M@128M";
+		};
+	};
+
+	fragment@8 {
+		target-path = "/chosen";
+		__dormant__ {
+			bootargs = "cma=64M@64M";
+		};
+	};
+
+	__overrides__ {
+		cma-256 = <0>,"+4-5-6-7-8";
+		cma-192 = <0>,"-4+5-6-7-8";
+		cma-128 = <0>,"-4-5+6-7-8";
+		cma-96  = <0>,"-4-5-6+7-8";
+		cma-64  = <0>,"-4-5-6-7+8";
+	};
 };