> From: Clark Wang <xiaoning.wang@xxxxxxx>
> Sent: Wednesday, March 17, 2021 2:54 PM
>
> 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.
>
> Reviewed-by: Fugang Duan <fugang.duan@xxxxxxx>
> Signed-off-by: Clark Wang <xiaoning.wang@xxxxxxx>
> ---
> 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 7216a393095d..5dbe85126f24 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
Where is this ratio coming from?
Can you describe why use it in commit message?
Regards
Aisheng
> #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
