diff --git a/proxyclient/experiments/jpeg.py b/proxyclient/experiments/jpeg.py
index 3c5a14e2..ee2f46c2 100644
--- a/proxyclient/experiments/jpeg.py
+++ b/proxyclient/experiments/jpeg.py
@@ -406,7 +406,7 @@ def set_default_regs(param1=0):
     jpeg.CHROMA_DOUBLE_H.val = 0
     jpeg.CHROMA_QUADRUPLE_H.val = 0
     jpeg.CHROMA_DOUBLE_V.val = 0
-    jpeg.REG_0x15c.val = 0
+    jpeg.PLANAR_CHROMA_HALVING.val = 0
     jpeg.PX_USE_PLANE1.val = 0
     jpeg.PX_TILES_W.val = 1
     jpeg.PX_TILES_H.val = 1
@@ -441,9 +441,9 @@ def set_default_regs(param1=0):
     jpeg.REG_0x118.val = 0
     jpeg.REG_0x11c.val = 0
     jpeg.REG_0x120.val = 0
-    jpeg.REG_0x124.val = 0
-    jpeg.REG_0x128.val = 0
-    jpeg.REG_0x12c.val = 0
+    jpeg.TILING_ENABLE.val = 0
+    jpeg.TILING_PLANE0.val = 0
+    jpeg.TILING_PLANE1.val = 0
     jpeg.DECODE_MACROBLOCKS_W.val = 0
     jpeg.DECODE_MACROBLOCKS_H.val = 0
     jpeg.SCALE_FACTOR.val = 0
diff --git a/proxyclient/m1n1/hw/jpeg.py b/proxyclient/m1n1/hw/jpeg.py
index 26c6d777..c92bfe08 100644
--- a/proxyclient/m1n1/hw/jpeg.py
+++ b/proxyclient/m1n1/hw/jpeg.py
@@ -177,10 +177,11 @@ class JPEGRegs(RegMap):
     REG_0x11c = 0x11c, Register32
 
     REG_0x120 = 0x120, Register32
-    # driver mentions surface tiling, but this doesn't seem to work???
-    REG_0x124 = 0x124, Register32
-    REG_0x128 = 0x128, Register32
-    REG_0x12c = 0x12c, Register32
+
+    # details not understood yet
+    TILING_ENABLE = 0x124, Register32
+    TILING_PLANE0 = 0x128, Register32
+    TILING_PLANE1 = 0x12c, Register32
 
     DECODE_MACROBLOCKS_W = 0x130, Register32
     DECODE_MACROBLOCKS_H = 0x134, Register32
@@ -198,7 +199,7 @@ class JPEGRegs(RegMap):
     RGBA_ORDER = 0x154, Register32
     RGBA_ALPHA = 0x158, Register32
 
-    REG_0x15c = 0x15c, Register32
+    PLANAR_CHROMA_HALVING = 0x15c, Register32
 
     REG_0x160 = 0x160, Register32
     REG_0x164 = 0x164, Register32