* Switched default PCI speed for 8540 ADS back to 33MHz

* Added comments and a printf to warn that PCI-X won't work at 33MHz Patch by Andy Fleming 17-Mar-2006 Signed-off-by: Andy Fleming <afleming@freescale.com>

* Switched default PCI speed for 8540 ADS back to 33MHz
* Added comments and a printf to warn that PCI-X won't work at 33MHz Patch by Andy Fleming 17-Mar-2006 Signed-off-by: Andy Fleming <afleming@freescale.com>
Matthew McClintock · Jon Loeliger
1 parent b6c5e1373b
Showing 3 changed files with 11 additions and 1 deletions Side-by-side Diff
cpu/mpc85xx/pci.c
doc/README.mpc85xxads
include/configs/MPC8540ADS.h
@@ -72,6 +72,9 @@
  
 	if (!(gur->pordevsr & PORDEVSR_PCI)) {
 		/* PCI-X init */
+		if (CONFIG_SYS_CLK_FREQ < 66000000)
+			printf("PCI-X will only work at 66 MHz\n");
+
 		reg16 = PCI_X_CMD_MAX_SPLIT | PCI_X_CMD_MAX_READ
 			| PCI_X_CMD_ERO | PCI_X_CMD_DPERR_E;
 		pci_hose_write_config_word(hose, dev, PCIX_COMMAND, reg16);
@@ -100,6 +100,9 @@
 	SW7[1:4]  =    0101 =  5    => 5 x 66	 = 330	CCB Sysclk
 	SW7[5:6]  =	 01	    => 5:2 x 330 = 825	Core clock
  
+    In order to use PCI-X (only in the first PCI slot.  The one with
+    the RIO connector), you need to set SW1[4] (config) to 1 (off).
+    Also, configure the board to run PCI at 66 MHz.
  
 2. MEMORY MAP TO WORK WITH LINUX KERNEL
  
@@ -68,10 +68,14 @@
  * The board, however, can run at 66MHz.  In any event, this value
  * must match the settings of some switches.  Details can be found
  * in the README.mpc85xxads.
+ *
+ * XXX -- Can't we run at 66 MHz, anyway?  PCI should drop to
+ * 33MHz to accommodate, based on a PCI pin.
+ * Note that PCI-X won't work at 33MHz.
  */
  
 #ifndef CONFIG_SYS_CLK_FREQ
-#define CONFIG_SYS_CLK_FREQ	66000000
+#define CONFIG_SYS_CLK_FREQ	33000000
 #endif
...	...	@@ -72,6 +72,9 @@
72	72
73	73	if (!(gur->pordevsr & PORDEVSR_PCI)) {
74	74	/* PCI-X init */
	75	+ if (CONFIG_SYS_CLK_FREQ < 66000000)
	76	+ printf("PCI-X will only work at 66 MHz\n");
	77	+
75	78	reg16 = PCI_X_CMD_MAX_SPLIT \| PCI_X_CMD_MAX_READ
76	79	\| PCI_X_CMD_ERO \| PCI_X_CMD_DPERR_E;
77	80	pci_hose_write_config_word(hose, dev, PCIX_COMMAND, reg16);
...	...	@@ -100,6 +100,9 @@
100	100	SW7[1:4] = 0101 = 5 => 5 x 66 = 330 CCB Sysclk
101	101	SW7[5:6] = 01 => 5:2 x 330 = 825 Core clock
102	102
	103	+ In order to use PCI-X (only in the first PCI slot. The one with
	104	+ the RIO connector), you need to set SW1[4] (config) to 1 (off).
	105	+ Also, configure the board to run PCI at 66 MHz.
103	106
104	107	2. MEMORY MAP TO WORK WITH LINUX KERNEL
105	108
...	...	@@ -68,10 +68,14 @@
68	68	* The board, however, can run at 66MHz. In any event, this value
69	69	* must match the settings of some switches. Details can be found
70	70	* in the README.mpc85xxads.
	71	+ *
	72	+ * XXX -- Can't we run at 66 MHz, anyway? PCI should drop to
	73	+ * 33MHz to accommodate, based on a PCI pin.
	74	+ * Note that PCI-X won't work at 33MHz.
71	75	*/
72	76
73	77	#ifndef CONFIG_SYS_CLK_FREQ
74		-#define CONFIG_SYS_CLK_FREQ 66000000
	78	+#define CONFIG_SYS_CLK_FREQ 33000000
75	79	#endif
76	80
77	81