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authorMaxime COQUELIN <maxime.coquelin@st.com>2014-07-23 17:44:07 +0200
committerWolfram Sang <wsa@the-dreams.de>2014-08-01 19:47:17 +0200
commit52976fa74b9da790686ee116424458c238564cb1 (patch)
tree16c9b609bf87346a42863e7ab7e159b02c72fa5e /drivers/i2c
parent28772ac8711e4d7268c06e765887dd8cb6924f98 (diff)
downloadlinux-52976fa74b9da790686ee116424458c238564cb1.tar.bz2
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>
Diffstat (limited to 'drivers/i2c')
-rw-r--r--drivers/i2c/busses/i2c-st.c32
1 files changed, 19 insertions, 13 deletions
diff --git a/drivers/i2c/busses/i2c-st.c b/drivers/i2c/busses/i2c-st.c
index fc767ddba3fb..2e4eccd6599a 100644
--- a/drivers/i2c/busses/i2c-st.c
+++ b/drivers/i2c/busses/i2c-st.c
@@ -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,
},
};