ppc4xx: Add CFG_MEM_TOP_HIDE to Denali SPD-based SDRAM setup

index 60f89c9..e20c9eb 100644
@@ -1093,10 +1093,10 @@ long int initdram(int board_type)
 
 	program_ddr0_06(dimm_ranks, iic0_dimm_addr, num_dimm_banks, sdram_freq);
 
-	/*------------------------------------------------------------------
+	/*
 	 * TODO: tFAW not found in SPD.  Value of 13 taken from Sequoia
-	 * board SDRAM, but may be overly concervate.
-	 *-----------------------------------------------------------------*/
+	 * board SDRAM, but may be overly conservative.
+	 */
 	mtsdram(DDR0_07, DDR0_07_NO_CMD_INIT_ENCODE(0) |
 		DDR0_07_TFAW_ENCODE(13) |
 		DDR0_07_AUTO_REFRESH_MODE_ENCODE(1) |

@@ -1181,26 +1181,29 @@ long int initdram(int board_type)
 	denali_wait_for_dlllock();
 
 #if defined(CONFIG_DDR_DATA_EYE)
-	/* -----------------------------------------------------------+
-	 * Perform data eye search if requested.
-	 * ----------------------------------------------------------*/
-	program_tlb(0, CFG_SDRAM_BASE, dram_size, TLB_WORD2_I_ENABLE);
+	/*
+	 * Map the first 1 MiB of memory in the TLB, and perform the data eye
+	 * search.
+	 */
+	program_tlb(0, CFG_SDRAM_BASE, TLB_1MB_SIZE, TLB_WORD2_I_ENABLE);
 	denali_core_search_data_eye();
 	denali_sdram_register_dump();
-	remove_tlb(CFG_SDRAM_BASE, dram_size);
+	remove_tlb(CFG_SDRAM_BASE, TLB_1MB_SIZE);
 #endif
 
 #if defined(CONFIG_ZERO_SDRAM) || defined(CONFIG_DDR_ECC)
 	program_tlb(0, CFG_SDRAM_BASE, dram_size, 0);
 	sync();
-	eieio();
 	/* Zero the memory */
 	debug("Zeroing SDRAM...");
-	dcbz_area(CFG_SDRAM_BASE, dram_size);
+#if defined(CFG_MEM_TOP_HIDE)
+	dcbz_area(CFG_SDRAM_BASE, dram_size - CFG_MEM_TOP_HIDE);
+#else
+#error Please define CFG_MEM_TOP_HIDE (see README) in your board config file
+#endif
 	dflush();
 	debug("Completed\n");
 	sync();
-	eieio();
 	remove_tlb(CFG_SDRAM_BASE, dram_size);
 
 #if defined(CONFIG_DDR_ECC)

@@ -1211,7 +1214,6 @@ long int initdram(int board_type)
 		u32 val;
 
 		sync();
-		eieio();
 		/* Clear error status */
 		mfsdram(DDR0_00, val);
 		mtsdram(DDR0_00, val | DDR0_00_INT_ACK_ALL);

@@ -1229,7 +1231,6 @@ long int initdram(int board_type)
 		print_mcsr();
 #endif
 		sync();
-		eieio();
 	}
 #endif /* defined(CONFIG_DDR_ECC) */
 #endif /* defined(CONFIG_ZERO_SDRAM) || defined(CONFIG_DDR_ECC) */