[U-Boot-Users] [PATCH] soft_i2c: Pull SDA high before reading

Haavard Skinnemoen haavard.skinnemoen at atmel.com
Fri May 16 11:08:11 CEST 2008


Spotted by Dean Capindale.

Systems that support open-drain GPIO properly are allowed provide an
empty I2C_TRISTATE define. However, this means that we need to be
careful not to drive SDA low when the slave is expected to respond.

This patch adds a missing I2C_SDA(1) to read_byte() required to
tristate the SDA line on systems that support open-drain GPIO.

Signed-off-by: Haavard Skinnemoen <haavard.skinnemoen at atmel.com>
---
 common/soft_i2c.c |    1 +
 1 files changed, 1 insertions(+), 0 deletions(-)

diff --git a/common/soft_i2c.c b/common/soft_i2c.c
index c5d7e20..5ef7f30 100644
--- a/common/soft_i2c.c
+++ b/common/soft_i2c.c
@@ -252,6 +252,7 @@ static uchar read_byte(int ack)
 	 * Read 8 bits, MSB first.
 	 */
 	I2C_TRISTATE;
+	I2C_SDA(1);
 	data = 0;
 	for(j = 0; j < 8; j++) {
 		I2C_SCL(0);
-- 
1.5.4.3





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