Seems like it infact only got 640x480x2 bytes so the size is probably correct. So reset it to the mp900/c standard. We want to see it boot before we fiddle to much.
diff --git a/arch/arm/mach-pxa/bsquare.c b/arch/arm/mach-pxa/bsquare.c
index d66eb3f..d0b4e0b 100644
--- a/arch/arm/mach-pxa/bsquare.c
+++ b/arch/arm/mach-pxa/bsquare.c
@@ -28,7 +28,7 @@
#define EPSONREGSTART 0x0C000000
#define EPSONREGLEN 0x00200000
#define EPSONFBSTART 0x0C200000
-#define EPSONFBLEN 1280*1024*2
+#define EPSONFBLEN 1280*1024
static void isp116x_pfm_delay(struct device *dev, int delay)
{
