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i2c: st: Update i2c timings 

The i2c timing values specified in the driver are the minimun values
defined in the I2C specifications. The I2C specification does not
specify any default or maximum values.

Some I2C devices are out of spec, such as the HDMI link of the Toshiba
19AV600 TV, and might not work properly with minimum values.

This patch adds a 10% margin on all the timings in both Normal and Fast modes.

Trial and error method have been used to find the minimum margin necessary to
have the out-of-spec device working, and a security margin has been added.

Signed-off-by: Maxime Coquelin <maxime.coquelin@st.com>
Signed-off-by: Wolfram Sang <wsa@the-dreams.de>
This commit is contained in:
Maxime COQUELIN 2014-07-23 17:44:07 +02:00 committed by Wolfram Sang
parent 28772ac871
commit 52976fa74b
1 changed files with 19 additions and 13 deletions
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32
drivers/i2c/busses/i2c-st.c
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@ -206,25 +206,31 @@ static inline void st_i2c_clr_bits(void __iomem *reg, u32 mask)
writel_relaxed(readl_relaxed(reg) & ~mask, reg);
}
/* From I2C Specifications v0.5 */
/*
* From I2C Specifications v0.5.
*
* All the values below have +10% margin added to be
* compatible with some out-of-spec devices,
* like HDMI link of the Toshiba 19AV600 TV.
*/
static struct st_i2c_timings i2c_timings[] = {
[I2C_MODE_STANDARD] = {
.rate = 100000,
.rep_start_hold = 4000,
.rep_start_setup = 4700,
.start_hold = 4000,
.data_setup_time = 250,
.stop_setup_time = 4000,
.bus_free_time = 4700,
.rep_start_hold = 4400,
.rep_start_setup = 5170,
.start_hold = 4400,
.data_setup_time = 275,
.stop_setup_time = 4400,
.bus_free_time = 5170,
},
[I2C_MODE_FAST] = {
.rate = 400000,
.rep_start_hold = 600,
.rep_start_setup = 600,
.start_hold = 600,
.data_setup_time = 100,
.stop_setup_time = 600,
.bus_free_time = 1300,
.rep_start_hold = 660,
.rep_start_setup = 660,
.start_hold = 660,
.data_setup_time = 110,
.stop_setup_time = 660,
.bus_free_time = 1430,
},
};