commit c831da9391144772cd6632b137fb2136eeb9c296
author Jon Smirl <jonsmirl@gmail.com> Sat Apr 04 17:44:51 2009 -0400
committer Wolfgang Denk <wd@denx.de> Sun Apr 05 01:34:08 2009 +0200
tree 47f3d741b2cfa59ffe8650c79e6755e847212d5b
parent e366f152f22a9454cdc5c68c17fdfd7c8cba344f

mpc5200: reduce delays in i2c

The previous code waited 1000us before checking i2c
status. Measurement shows i2c is usually ready in
under 50us. Change the polling interval to 15us,
loop 6,667 times to keep the polling timeout constant
at 100ms.

cpu/mpc5xxx/i2c.c

diff --git a/cpu/mpc5xxx/i2c.c b/cpu/mpc5xxx/i2c.c
index e2506d8..2341932 100644
--- a/cpu/mpc5xxx/i2c.c
+++ b/cpu/mpc5xxx/i2c.c
@@ -38,7 +38,7 @@
 #error CONFIG_SYS_I2C_MODULE is not properly configured
 #endif
 
-#define I2C_TIMEOUT	100
+#define I2C_TIMEOUT	6667
 #define I2C_RETRIES	3
 
 struct mpc5xxx_i2c_tap {
@@ -94,7 +94,7 @@
 		mpc_reg_out(&regs->mcr, 0, 0);
 		mpc_reg_out(&regs->mcr, I2C_EN, 0);
 #endif
-		udelay(1000);
+		udelay(15);
 		status = mpc_reg_in(&regs->msr);
 	}
 
@@ -109,7 +109,7 @@
 	*status = mpc_reg_in(&regs->msr);
 
 	while (timeout-- && !(*status & I2C_IF)) {
-		udelay(1000);
+		udelay(15);
 		*status = mpc_reg_in(&regs->msr);
 	}