4.14-stable review patch. If anyone has any objections, please let me know.
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[ Upstream commit ece27a337d42a3197935711997f2880f0957ed7e ]
Currently, the clock duty is set as tLOW/tHIGH = 1/1. For Fast-mode, tLOW is set to 1.25 us while the I2C spec requires tLOW >= 1.3 us.
tLOW/tHIGH = 5/4 would meet both Standard-mode and Fast-mode: Standard-mode: tLOW = 5.56 us, tHIGH = 4.44 us Fast-mode: tLOW = 1.39 us, tHIGH = 1.11 us
Signed-off-by: Masahiro Yamada yamada.masahiro@socionext.com Signed-off-by: Wolfram Sang wsa@the-dreams.de Signed-off-by: Sasha Levin sashal@kernel.org --- drivers/i2c/busses/i2c-uniphier-f.c | 19 ++++++++++++++++++- 1 file changed, 18 insertions(+), 1 deletion(-)
diff --git a/drivers/i2c/busses/i2c-uniphier-f.c b/drivers/i2c/busses/i2c-uniphier-f.c index a403e8579b65..bc26ec822e26 100644 --- a/drivers/i2c/busses/i2c-uniphier-f.c +++ b/drivers/i2c/busses/i2c-uniphier-f.c @@ -470,9 +470,26 @@ static void uniphier_fi2c_hw_init(struct uniphier_fi2c_priv *priv)
uniphier_fi2c_reset(priv);
+ /* + * Standard-mode: tLOW + tHIGH = 10 us + * Fast-mode: tLOW + tHIGH = 2.5 us + */ writel(cyc, priv->membase + UNIPHIER_FI2C_CYC); - writel(cyc / 2, priv->membase + UNIPHIER_FI2C_LCTL); + /* + * Standard-mode: tLOW = 4.7 us, tHIGH = 4.0 us, tBUF = 4.7 us + * Fast-mode: tLOW = 1.3 us, tHIGH = 0.6 us, tBUF = 1.3 us + * "tLow/tHIGH = 5/4" meets both. + */ + writel(cyc * 5 / 9, priv->membase + UNIPHIER_FI2C_LCTL); + /* + * Standard-mode: tHD;STA = 4.0 us, tSU;STA = 4.7 us, tSU;STO = 4.0 us + * Fast-mode: tHD;STA = 0.6 us, tSU;STA = 0.6 us, tSU;STO = 0.6 us + */ writel(cyc / 2, priv->membase + UNIPHIER_FI2C_SSUT); + /* + * Standard-mode: tSU;DAT = 250 ns + * Fast-mode: tSU;DAT = 100 ns + */ writel(cyc / 16, priv->membase + UNIPHIER_FI2C_DSUT);
uniphier_fi2c_prepare_operation(priv);