PPC440 DDR setup: Set SDRAM0_CFG0[PMU]=0 for best performance

AMCC suggested to set the PMU bit to 0 for best performace on
the PPC440 DDR controller.
Please see doc/README.440-DDR-performance for details.
Patch by Stefan Roese, 28 Jul 2006

CHANGELOG

@@ -2,6 +2,12 @@
 Changes since U-Boot 1.1.4:
 ======================================================================
 
+* PPC440 DDR setup: Set SDRAM0_CFG0[PMU]=0 for best performance
+  AMCC suggested to set the PMU bit to 0 for best performace on
+  the PPC440 DDR controller.
+  Please see doc/README.440-DDR-performance for details.
+  Patch by Stefan Roese, 28 Jul 2006
+
 * AMCC bamboo (440EP) U-Boot image reduced to 384kbyte
   Please see doc/README.bamboo for details.
   Patch by Stefan Roese, 27 Jul 2006

board/amcc/yellowstone/yellowstone.c

@@ -313,13 +313,13 @@ void sdram_init(void)
 	mtsdram(mem_tr0, 0x410a4012);	/* ?? */
 	mtsdram(mem_rtr, 0x04080000);	/* ?? */
 	mtsdram(mem_cfg1, 0x00000000);	/* Self-refresh exit, disable PM    */
-	mtsdram(mem_cfg0, 0x34000000);	/* Disable EEC */
+	mtsdram(mem_cfg0, 0x30000000);	/* Disable EEC */
 	udelay(400);		/* Delay 200 usecs (min)            */
 
 	/*--------------------------------------------------------------------
 	 * Enable the controller, then wait for DCEN to complete
 	 *------------------------------------------------------------------*/
-	mtsdram(mem_cfg0, 0x84000000);	/* Enable */
+	mtsdram(mem_cfg0, 0x80000000);	/* Enable */
 
 	for (;;) {
 		mfsdram(mem_mcsts, reg);

board/amcc/yosemite/yosemite.c

@@ -309,13 +309,13 @@ void sdram_init(void)
 	mtsdram(mem_tr0, 0x410a4012);	/* ?? */
 	mtsdram(mem_rtr, 0x04080000);	/* ?? */
 	mtsdram(mem_cfg1, 0x00000000);	/* Self-refresh exit, disable PM    */
-	mtsdram(mem_cfg0, 0x34000000);	/* Disable EEC */
+	mtsdram(mem_cfg0, 0x30000000);	/* Disable EEC */
 	udelay(400);		/* Delay 200 usecs (min)            */
 
 	/*--------------------------------------------------------------------
 	 * Enable the controller, then wait for DCEN to complete
 	 *------------------------------------------------------------------*/
-	mtsdram(mem_cfg0, 0x84000000);	/* Enable */
+	mtsdram(mem_cfg0, 0x80000000);	/* Enable */
 
 	for (;;) {
 		mfsdram(mem_mcsts, reg);

cpu/ppc4xx/sdram.c

@@ -379,7 +379,7 @@ long int initdram(int board_type)
 		/*
 		 * Enable the controller, then wait for DCEN to complete
 		 */
-		mtsdram(mem_cfg0, 0x86000000);	/* DCEN=1, PMUD=1, 64-bit	*/
+		mtsdram(mem_cfg0, 0x82000000);	/* DCEN=1, PMUD=0, 64-bit	*/
 		udelay(10000);
 
 		if (get_ram_size(0, mb0cf[i].size) == mb0cf[i].size) {

cpu/ppc4xx/spd_sdram.c

@@ -1007,9 +1007,9 @@ void program_cfg0(unsigned long* dimm_populated,
 	}
 
 	/*
-	 * program Page Management Unit
+	 * program Page Management Unit (0 == enabled)
 	 */
-	cfg0 |= SDRAM_CFG0_PMUD;
+	cfg0 &= ~SDRAM_CFG0_PMUD;
 
 	/*
 	 * program Memory Controller Options 0

doc/README.440-DDR-performance

@@ -0,0 +1,90 @@
+AMCC suggested to set the PMU bit to 0 for best performace on the
+PPC440 DDR controller. The 440er common DDR setup files (sdram.c &
+spd_sdram.c) are changed accordingly. So all 440er boards using
+these setup routines will automatically receive this performance
+increase.
+
+Please see below some benchmarks done by AMCC to demonstrate this
+performance changes:
+
+
+----------------------------------------
+SDRAM0_CFG0[PMU] = 1 (U-boot default for Bamboo, Yosemite and Yellowstone)
+----------------------------------------
+Stream benchmark results
+-------------------------------------------------------------
+This system uses 8 bytes per DOUBLE PRECISION word.
+-------------------------------------------------------------
+Array size = 2000000, Offset = 0
+Total memory required = 45.8 MB.
+Each test is run 10 times, but only
+the *best* time for each is used.
+-------------------------------------------------------------
+Your clock granularity/precision appears to be 1 microseconds.
+Each test below will take on the order of 112345 microseconds.
+   (= 112345 clock ticks)
+Increase the size of the arrays if this shows that you are not getting
+at least 20 clock ticks per test.
+-------------------------------------------------------------
+WARNING -- The above is only a rough guideline.
+For best results, please be sure you know the precision of your system
+timer.
+-------------------------------------------------------------
+Function      Rate (MB/s)   RMS time     Min time     Max time
+Copy:         256.7683       0.1248       0.1246       0.1250
+Scale:        246.0157       0.1302       0.1301       0.1302
+Add:          255.0316       0.1883       0.1882       0.1885
+Triad:        253.1245       0.1897       0.1896       0.1899
+
+
+TTCP Benchmark Results
+ttcp-t: socket
+ttcp-t: connect
+ttcp-t: buflen=8192, nbuf=2048, align=16384/0, port=5000  tcp  ->
+localhost
+ttcp-t: 16777216 bytes in 0.28 real seconds = 454.29 Mbit/sec +++
+ttcp-t: 2048 I/O calls, msec/call = 0.14, calls/sec = 7268.57
+ttcp-t: 0.0user 0.1sys 0:00real 60% 0i+0d 0maxrss 0+2pf 3+1506csw
+
+----------------------------------------
+SDRAM0_CFG0[PMU] = 0 (Suggested modification)
+Setting PMU = 0 provides a noticeable performance improvement *2% to
+5% improvement in memory performance.
+*Improves the Mbit/sec for TTCP benchmark by almost 76%.
+----------------------------------------
+Stream benchmark results
+-------------------------------------------------------------
+This system uses 8 bytes per DOUBLE PRECISION word.
+-------------------------------------------------------------
+Array size = 2000000, Offset = 0
+Total memory required = 45.8 MB.
+Each test is run 10 times, but only
+the *best* time for each is used.
+-------------------------------------------------------------
+Your clock granularity/precision appears to be 1 microseconds.
+Each test below will take on the order of 120066 microseconds.
+   (= 120066 clock ticks)
+Increase the size of the arrays if this shows that you are not getting
+at least 20 clock ticks per test.
+-------------------------------------------------------------
+WARNING -- The above is only a rough guideline.
+For best results, please be sure you know the precision of your system
+timer.
+-------------------------------------------------------------
+Function      Rate (MB/s)   RMS time     Min time     Max time
+Copy:         262.5167       0.1221       0.1219       0.1223
+Scale:        258.4856       0.1238       0.1238       0.1240
+Add:          262.5404       0.1829       0.1828       0.1831
+Triad:        266.8594       0.1800       0.1799       0.1802
+
+TTCP Benchmark Results
+ttcp-t: socket
+ttcp-t: connect
+ttcp-t: buflen=8192, nbuf=2048, align=16384/0, port=5000  tcp  ->
+localhost
+ttcp-t: 16777216 bytes in 0.16 real seconds = 804.06 Mbit/sec +++
+ttcp-t: 2048 I/O calls, msec/call = 0.08, calls/sec = 12864.89
+ttcp-t: 0.0user 0.0sys 0:00real 46% 0i+0d 0maxrss 0+2pf 120+1csw
+
+
+2006-07-28, Stefan Roese <sr@denx.de>