Hi Qii,
On Wed, Feb 3, 2021 at 6:43 PM <qii.wang@xxxxxxxxxxxx> wrote:
>
> From: Qii Wang <qii.wang@xxxxxxxxxxxx>
>
> tSU,STA/tHD,STA/tSU,STOP maybe out of spec due to device
> clock-stretching or circuit loss, we could get device
> clock-stretch time from dts to adjust these parameters
> to meet the spec via EXT_CONF register.
>
> Signed-off-by: Qii Wang <qii.wang@xxxxxxxxxxxx>
> ---
> drivers/i2c/busses/i2c-mt65xx.c | 6 +++++-
> 1 file changed, 5 insertions(+), 1 deletion(-)
>
> diff --git a/drivers/i2c/busses/i2c-mt65xx.c b/drivers/i2c/busses/i2c-mt65xx.c
> index 2ffd2f3..47c7255 100644
> --- a/drivers/i2c/busses/i2c-mt65xx.c
> +++ b/drivers/i2c/busses/i2c-mt65xx.c
> @@ -245,6 +245,7 @@ struct mtk_i2c {
> u16 irq_stat; /* interrupt status */
> unsigned int clk_src_div;
> unsigned int speed_hz; /* The speed in transfer */
> + unsigned int clock_stretch_ns;
> enum mtk_trans_op op;
> u16 timing_reg;
> u16 high_speed_reg;
> @@ -607,7 +608,8 @@ static int mtk_i2c_check_ac_timing(struct mtk_i2c *i2c,
> else
> clk_ns = sample_ns / 2;
>
> - su_sta_cnt = DIV_ROUND_UP(spec->min_su_sta_ns, clk_ns);
> + su_sta_cnt = DIV_ROUND_UP(spec->min_su_sta_ns + i2c->clock_stretch_ns,
> + clk_ns);
> if (su_sta_cnt > max_sta_cnt)
> return -1;
>
> @@ -1171,6 +1173,8 @@ static int mtk_i2c_parse_dt(struct device_node *np, struct mtk_i2c *i2c)
> if (i2c->clk_src_div == 0)
> return -EINVAL;
>
> + of_property_read_u32(np, "clock-stretch-ns", &i2c->clock_stretch_ns);
> +
I think this new property "clock-stretch-ns" is for the same purpose of
"i2c-scl-falling-time-ns" + "i2c-scl-rising-time-ns" defined in
Documentation/devicetree/bindings/i2c/i2c.txt?
> i2c->have_pmic = of_property_read_bool(np, "mediatek,have-pmic");
> i2c->use_push_pull =
> of_property_read_bool(np, "mediatek,use-push-pull");
> --
> 1.9.1
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