From fab356a0b87d57d474d6e87408f1ede98a503150 Mon Sep 17 00:00:00 2001 From: Hans de Goede Date: Sat, 3 May 2014 17:46:26 +0200 Subject: [PATCH] mvtwsi: Fix clock programming The TWSI_FREQUENCY macro was wrong in 2 ways: 1) It was casting the result of the calculations to an u8, while i2c clk rates are often >= 100Khz which won't fit in a u8, drop the cast. 2) It had an extra factor of 2 in the divider which neither the datasheet nor the Linux driver have. The comment for the default value was wrongly saying that m lives in bits 4-7, while in reality it is in bits 3-6, as can be seen from the correct shift by 3 used in i2c_init(). While at it remove the unused twsi_actual_speed variable. Signed-off-by: Hans de Goede --- drivers/i2c/mvtwsi.c | 7 ++----- 1 file changed, 2 insertions(+), 5 deletions(-) diff --git a/drivers/i2c/mvtwsi.c b/drivers/i2c/mvtwsi.c index 90c83879182..b44944378a9 100644 --- a/drivers/i2c/mvtwsi.c +++ b/drivers/i2c/mvtwsi.c @@ -216,7 +216,7 @@ static int twsi_stop(int status) */ #define TWSI_FREQUENCY(m, n) \ - ((u8) (CONFIG_SYS_TCLK / (10 * (m + 1) * 2 * (1 << n)))) + (CONFIG_SYS_TCLK / (10 * (m + 1) * (1 << n))) /* * These are required to be reprogrammed before enabling the controller @@ -225,10 +225,8 @@ static int twsi_stop(int status) * twsi_slave_address left uninitialized lest checkpatch.pl complains. */ -/* Baudrate generator: m (bits 7..4) =4, n (bits 3..0) =4 */ +/* Baudrate generator: m (bits 6..3) = 8, n (bits 2..0) = 4 */ static u8 twsi_baud_rate = 0x44; /* baudrate at controller reset */ -/* Default frequency corresponding to default m=4, n=4 */ -static u8 twsi_actual_speed = TWSI_FREQUENCY(4, 4); /* Default slave address is 0 (so is an uninitialized static) */ static u8 twsi_slave_address; @@ -279,7 +277,6 @@ void i2c_init(int requested_speed, int slaveadd) } /* save baud rate and slave for later calls to twsi_reset */ twsi_baud_rate = baud; - twsi_actual_speed = highest_speed; twsi_slave_address = slaveadd; /* reset controller */ twsi_reset();