[U-Boot] [PATCH V3] mpc5200: reduce delays in i2c

[Jon Smirl]

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. Try four
times at a 15us delay and then revert to the previous behavior
of 1ms delays.
---
 cpu/mpc5xxx/i2c.c |    9 +++++----
 1 files changed, 5 insertions(+), 4 deletions(-)

diff --git a/cpu/mpc5xxx/i2c.c b/cpu/mpc5xxx/i2c.c
index e2506d8..dba9071 100644
--- a/cpu/mpc5xxx/i2c.c
+++ b/cpu/mpc5xxx/i2c.c
@@ -39,6 +39,7 @@ DECLARE_GLOBAL_DATA_PTR;
 #endif
 
 #define I2C_TIMEOUT    100
+#define I2C_TIMEOUT_QUICK 4
 #define I2C_RETRIES    3
 
 struct mpc5xxx_i2c_tap {
@@ -80,7 +81,7 @@ static void mpc_reg_out(volatile u32 *reg, int val, int mask)
 static int wait_for_bb(void)
 {
        struct mpc5xxx_i2c *regs    = (struct mpc5xxx_i2c *)I2C_BASE;
-       int                 timeout = I2C_TIMEOUT;
+       int                 timeout = I2C_TIMEOUT + I2C_TIMEOUT_QUICK;
        int                 status;
 
        status = mpc_reg_in(&regs->msr);
@@ -94,7 +95,7 @@ static int wait_for_bb(void)
                mpc_reg_out(&regs->mcr, 0, 0);
                mpc_reg_out(&regs->mcr, I2C_EN, 0);
 #endif
-               udelay(1000);
+               timeout > I2C_TIMEOUT ? udelay(15) : udelay(1000);
                status = mpc_reg_in(&regs->msr);
        }
 
@@ -104,12 +105,12 @@ static int wait_for_bb(void)
 static int wait_for_pin(int *status)
 {
        struct mpc5xxx_i2c *regs    = (struct mpc5xxx_i2c *)I2C_BASE;
-       int                 timeout = I2C_TIMEOUT;
+       int                 timeout = I2C_TIMEOUT + I2C_TIMEOUT_QUICK;
 
        *status = mpc_reg_in(&regs->msr);
 
        while (timeout-- && !(*status & I2C_IF)) {
-               udelay(1000);
+               timeout > I2C_TIMEOUT ? udelay(15) : udelay(1000);
                *status = mpc_reg_in(&regs->msr);
        }
 

_______________________________________________
U-Boot mailing list
U-Boot@lists.denx.de
http://lists.denx.de/mailman/listinfo/u-boot