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    Subject[PATCH V2 12/18] i2c: imx-lpi2c: fix i2c timing issue
    Date
    The clkhi and clklo ratio was not very precise before that can make the
    time of START/STOP/HIGH LEVEL out of specification.

    Therefore, the calculation of these times has been modified in this patch.
    At the same time, the mode rate definition of i2c is corrected.

    Signed-off-by: Clark Wang <xiaoning.wang@nxp.com>
    Reviewed-by: Fugang Duan <fugang.duan@nxp.com>
    ---
    V2 changes:
    - No change.
    ---
    drivers/i2c/busses/i2c-imx-lpi2c.c | 27 ++++++++++++++-------------
    1 file changed, 14 insertions(+), 13 deletions(-)

    diff --git a/drivers/i2c/busses/i2c-imx-lpi2c.c b/drivers/i2c/busses/i2c-imx-lpi2c.c
    index 77dd6ee5a4a8..d124c4000823 100644
    --- a/drivers/i2c/busses/i2c-imx-lpi2c.c
    +++ b/drivers/i2c/busses/i2c-imx-lpi2c.c
    @@ -73,17 +73,17 @@
    #define MCFGR1_IGNACK BIT(9)
    #define MRDR_RXEMPTY BIT(14)

    -#define I2C_CLK_RATIO 2
    +#define I2C_CLK_RATIO 24 / 59
    #define CHUNK_DATA 256

    #define I2C_PM_TIMEOUT 1000 /* ms */

    enum lpi2c_imx_mode {
    - STANDARD, /* 100+Kbps */
    - FAST, /* 400+Kbps */
    - FAST_PLUS, /* 1.0+Mbps */
    - HS, /* 3.4+Mbps */
    - ULTRA_FAST, /* 5.0+Mbps */
    + STANDARD, /* <=100Kbps */
    + FAST, /* <=400Kbps */
    + FAST_PLUS, /* <=1.0Mbps */
    + HS, /* <=3.4Mbps */
    + ULTRA_FAST, /* <=5.0Mbps */
    };

    enum lpi2c_imx_pincfg {
    @@ -156,13 +156,13 @@ static void lpi2c_imx_set_mode(struct lpi2c_imx_struct *lpi2c_imx)
    unsigned int bitrate = lpi2c_imx->bitrate;
    enum lpi2c_imx_mode mode;

    - if (bitrate < I2C_MAX_FAST_MODE_FREQ)
    + if (bitrate <= I2C_MAX_STANDARD_MODE_FREQ)
    mode = STANDARD;
    - else if (bitrate < I2C_MAX_FAST_MODE_PLUS_FREQ)
    + else if (bitrate <= I2C_MAX_FAST_MODE_FREQ)
    mode = FAST;
    - else if (bitrate < I2C_MAX_HIGH_SPEED_MODE_FREQ)
    + else if (bitrate <= I2C_MAX_FAST_MODE_PLUS_FREQ)
    mode = FAST_PLUS;
    - else if (bitrate < I2C_MAX_ULTRA_FAST_MODE_FREQ)
    + else if (bitrate <= I2C_MAX_HIGH_SPEED_MODE_FREQ)
    mode = HS;
    else
    mode = ULTRA_FAST;
    @@ -209,7 +209,8 @@ static void lpi2c_imx_stop(struct lpi2c_imx_struct *lpi2c_imx)
    } while (1);
    }

    -/* CLKLO = I2C_CLK_RATIO * CLKHI, SETHOLD = CLKHI, DATAVD = CLKHI/2 */
    +/* CLKLO = (1 - I2C_CLK_RATIO) * clk_cycle, SETHOLD = CLKHI, DATAVD = CLKHI/2
    + CLKHI = I2C_CLK_RATIO * clk_cycle */
    static int lpi2c_imx_config(struct lpi2c_imx_struct *lpi2c_imx)
    {
    u8 prescale, filt, sethold, clkhi, clklo, datavd;
    @@ -232,8 +233,8 @@ static int lpi2c_imx_config(struct lpi2c_imx_struct *lpi2c_imx)

    for (prescale = 0; prescale <= 7; prescale++) {
    clk_cycle = clk_rate / ((1 << prescale) * lpi2c_imx->bitrate)
    - - 3 - (filt >> 1);
    - clkhi = (clk_cycle + I2C_CLK_RATIO) / (I2C_CLK_RATIO + 1);
    + - (2 + filt) / (1 << prescale);
    + clkhi = clk_cycle * I2C_CLK_RATIO;
    clklo = clk_cycle - clkhi;
    if (clklo < 64)
    break;
    --
    2.25.1
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