X-Git-Url: https://git.librecmc.org/?a=blobdiff_plain;f=cpu%2Fmpc824x%2Fcpu_init.c;h=7871031b9709610ac9fa805992b1260af8172902;hb=b706d63559aeec352bc72dd86d7d5423c15f6a60;hp=d0c7a3bcabc3225adf96bf9e5820ac7197b47ef0;hpb=281e00a3be453a169d854f824a460359d10f92bb;p=oweals%2Fu-boot.git

diff --git a/cpu/mpc824x/cpu_init.c b/cpu/mpc824x/cpu_init.c
index d0c7a3bcab..7871031b97 100644
--- a/cpu/mpc824x/cpu_init.c
+++ b/cpu/mpc824x/cpu_init.c
@@ -90,7 +90,7 @@ cpu_init_f (void)
 #endif
 
 	CONFIG_WRITE_BYTE(PCLSR, 0x8);	/* set PCI cache line size */
-
+	CONFIG_WRITE_BYTE (PLTR, 0x40); /* set PCI latency timer */
 	/*
 	* Note that although this bit is cleared after a hard reset, it
 	* must be explicitly set and then cleared by software during
@@ -106,6 +106,21 @@ cpu_init_f (void)
 	CONFIG_READ_BYTE(AMBOR,val);
 	CONFIG_WRITE_BYTE(AMBOR,val|0x1);
 
+#if 0
+	/*
+	 * The following bug only affects older (XPC8245) processors.
+	 * DMA transfers initiated by external devices get corrupted due
+	 * to a hardware scheduling problem.
+	 *
+	 * The effect is:
+	 * when transferring X words, the first 32 words are transferred
+	 * OK, the next 3 x 32 words are 'old' data (from previous DMA)
+	 * while the rest of the X words is xferred fine.
+	 *
+	 * Disabling 3 of the 4 32 word hardware buffers solves the problem
+	 * with no significant performance loss.
+	 */
+
 	CONFIG_READ_BYTE(PCMBCR,val);
 	/* in order not to corrupt data which is being read over the PCI bus
 	* with the PPC as slave, we need to reduce the number of PCMRBs to 1,
@@ -117,10 +132,8 @@ cpu_init_f (void)
 #else
 	CONFIG_WRITE_BYTE(PCMBCR,(val|0x80)); /* 2 PCMRBs */
 	CONFIG_WRITE_BYTE(PCMBCR,(val|0x40)); /* 3 PCMRBs */
-	/* default, 4 PCMRBs are used, so don't change the
-	 * register is this is _really_ what you want: data
-	 * corruption with no performance gain
-	 */
+	/* default, 4 PCMRBs are used */
+#endif
 #endif
 #endif