[PATCH 3/3] i2c: mediatek: Use scl_int_delay_ns to compensate clock-stretching

From: Qii Wang
Date: Sat Apr 17 2021 - 02:47:25 EST


The parameters of tSU,STA/tHD,STA/tSU,STOP maybe out of spec due
to device clock-stretch or circuit loss, we could get a suitable
scl_int_delay_ns from i2c_timings to compensate 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 bf25acb..5ddfa4e 100644
--- a/drivers/i2c/busses/i2c-mt65xx.c
+++ b/drivers/i2c/busses/i2c-mt65xx.c
@@ -231,6 +231,7 @@ struct mtk_i2c {
struct i2c_adapter adap; /* i2c host adapter */
struct device *dev;
struct completion msg_complete;
+ struct i2c_timings timing_info;

/* set in i2c probe */
void __iomem *base; /* i2c base addr */
@@ -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->timing_info.scl_int_delay_ns, clk_ns);
if (su_sta_cnt > max_sta_cnt)
return -1;

@@ -1176,6 +1178,8 @@ static int mtk_i2c_parse_dt(struct device_node *np, struct mtk_i2c *i2c)
i2c->use_push_pull =
of_property_read_bool(np, "mediatek,use-push-pull");

+ i2c_parse_fw_timings(i2c->dev, &i2c->timing_info, true);
+
return 0;
}

--
1.9.1