[PATCH] i2c: mediatek: Get device clock-stretch time via dts

Subsystems: i2c subsystem, i2c subsystem host drivers, mediatek i2c controller driver, the rest

STALE2006d

4 messages, 2 authors, 2021-03-02 · open the first message on its own page

[PATCH] i2c: mediatek: Get device clock-stretch time via dts

From: <qii.wang@mediatek.com>
Date: 2021-02-03 10:36:37 

From: Qii Wang <qii.wang@mediatek.com>

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@mediatek.com>
---
 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);
+
 	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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Re: [PATCH] i2c: mediatek: Get device clock-stretch time via dts

From: Qii Wang <qii.wang@mediatek.com>
Date: 2021-03-01 12:23:27 

Hi,
On Wed, 2021-02-03 at 18:35 +0800, qii.wang@mediatek.com wrote:
From: Qii Wang <qii.wang@mediatek.com>

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@mediatek.com>
---
Can it merge into 5.12? or do I need to resend the patch?

Thanks,
	Qii
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Re: [PATCH] i2c: mediatek: Get device clock-stretch time via dts

From: Ikjoon Jang <hidden>
Date: 2021-03-02 12:04:32 

Hi Qii,

On Wed, Feb 3, 2021 at 6:43 PM [off-list ref] wrote:
quoted hunk
From: Qii Wang <qii.wang@mediatek.com>

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@mediatek.com>
---
 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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Re: [PATCH] i2c: mediatek: Get device clock-stretch time via dts

From: Qii Wang <qii.wang@mediatek.com>
Date: 2021-03-02 14:11:01 

Hi,
On Tue, 2021-03-02 at 19:30 +0800, Ikjoon Jang wrote:
Hi Qii,
quoted
@@ -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?
I haven't find the corresponding instructions;and this patch is for the
problem caused by clock-stretch when the scl is pulled.

quoted
        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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