On an i2c bus, scl and sda are pulled high through pull-up resistors. Thus,
turning off the output drivers is enough to get a logical 1 when necessary
and allows the salve to pull down the nets to do clock stretching or to
generate ACK conditions. This patch does just that: output drivers are tuned off
if a logical 1 is to be driven on the sda or scl line.
Signed-off-by: Jean-Hugues Deschenes <jean-hugues.desche...@octasic.com>
Index: igb-5.2.9.4-ori/src/igb_main.c
===================================================================
--- igb-5.2.9.4-ori.orig/src/igb_main.c 2014-11-26 11:20:27.395762986 -0500
+++ igb-5.2.9.4-ori/src/igb_main.c 2014-11-26 13:04:30.845271718 -0500
@@ -1657,12 +1657,9 @@
s32 i2cctl = E1000_READ_REG(hw, E1000_I2CPARAMS);
if (state)
- i2cctl |= E1000_I2C_DATA_OUT;
+ i2cctl |= E1000_I2C_DATA_OUT | E1000_I2C_DATA_OE_N;
else
- i2cctl &= ~E1000_I2C_DATA_OUT;
-
- i2cctl &= ~E1000_I2C_DATA_OE_N;
- i2cctl |= E1000_I2C_CLK_OE_N;
+ i2cctl &= ~E1000_I2C_DATA_OUT & ~E1000_I2C_DATA_OE_N;
E1000_WRITE_REG(hw, E1000_I2CPARAMS, i2cctl);
E1000_WRITE_FLUSH(hw);
@@ -1681,13 +1678,11 @@
struct e1000_hw *hw = &adapter->hw;
s32 i2cctl = E1000_READ_REG(hw, E1000_I2CPARAMS);
- if (state) {
- i2cctl |= E1000_I2C_CLK_OUT;
- i2cctl &= ~E1000_I2C_CLK_OE_N;
- } else {
- i2cctl &= ~E1000_I2C_CLK_OUT;
- i2cctl &= ~E1000_I2C_CLK_OE_N;
- }
+ if (state)
+ i2cctl |= E1000_I2C_CLK_OUT | E1000_I2C_CLK_OE_N;
+ else
+ i2cctl &= ~E1000_I2C_CLK_OUT & ~E1000_I2C_CLK_OE_N;
+
E1000_WRITE_REG(hw, E1000_I2CPARAMS, i2cctl);
E1000_WRITE_FLUSH(hw);
}
------------------------------------------------------------------------------
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