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From: Jon Smirl <jonsmirl@gmail.com>
To: u-boot@lists.denx.de
Subject: [U-Boot] [PATCH V2] mpc5200: reduce delays in i2c
Date: Mon, 30 Mar 2009 21:03:30 -0400	[thread overview]
Message-ID: <20090331010330.20946.41742.stgit@localhost> (raw)

Make the i2c delays smaller. The measured delay is 55us at
100Khz. Set the delay to 15us which should work for 400Khz.
100Khz will loop four times and get a 60us delay. Previous
total delay was 100,000us new total delay is 150,000us before
timeout.

Signed-off-by: Jon Smirl <jonsmirl@gmail.com>

---
 cpu/mpc5xxx/i2c.c |    6 +++---
 1 files changed, 3 insertions(+), 3 deletions(-)

diff --git a/cpu/mpc5xxx/i2c.c b/cpu/mpc5xxx/i2c.c
index e2506d8..48b6464 100644
--- a/cpu/mpc5xxx/i2c.c
+++ b/cpu/mpc5xxx/i2c.c
@@ -38,7 +38,7 @@ DECLARE_GLOBAL_DATA_PTR;
 #error CONFIG_SYS_I2C_MODULE is not properly configured
 #endif
 
-#define I2C_TIMEOUT	100
+#define I2C_TIMEOUT	10000
 #define I2C_RETRIES	3
 
 struct mpc5xxx_i2c_tap {
@@ -94,7 +94,7 @@ static int wait_for_bb(void)
 		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 @@ static int wait_for_pin(int *status)
 	*status = mpc_reg_in(&regs->msr);
 
 	while (timeout-- && !(*status & I2C_IF)) {
-		udelay(1000);
+		udelay(15);
 		*status = mpc_reg_in(&regs->msr);
 	}
 

             reply	other threads:[~2009-03-31  1:03 UTC|newest]

Thread overview: 3+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2009-03-31  1:03 Jon Smirl [this message]
2009-03-31 20:54 ` [U-Boot] [PATCH V2] mpc5200: reduce delays in i2c Wolfgang Denk
2009-03-31 21:15   ` Jon Smirl

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