[PATCH v8 0/5] Introducing an attribute to select the time setting

[PATCH v8 0/5] Introducing an attribute to select the time setting

[Kewei Xu]

v7:
Resubmit the patch based on version 5.15-rc1

v6:
1. Add the judgment condition, clear the handshake signal between dma and
i2c when multiple msgs are transmitted.

v5:
1. Replace the previous variable name "default_timing_adjust" with "use-default-timing"
2. Added waiting for dma reset mechanism
3. Remove received patch(dt-bindings: i2c: update bindings for MT8195 SOC)

v4:
1. Remove the repeated assignment of the inter_clk_div parameter
2. Modify the wrong assignment of OFFSET_MULTI_DMA
3. Unify the log print format of the i2c_dump_register() and drop the extra outer parentheses
4. Place the fixes at the very least
5. Add fixed tags 25708278f810 ("i2c: mediatek: Add i2c support for MediaTek MT8183")
6. Add "i2c: mediatek: modify bus speed calculation formula"
7. Fix single line characters exceeding 80 characters
8. Combine two different series of patches.

v3:
1. Fix code errors caused by v2 modification

v2:
1. Add "dt-bindings: i2c: add attribute default-timing-adjust"
2. Split the fix into sepatate patch.

Kewei Xu (5):
  i2c: mediatek: Reset the handshake signal between i2c and dma
  i2c: mediatek: Dump i2c/dma register when a timeout occurs
  dt-bindings: i2c: add attribute use-default-timing
  i2c: mediatek: Isolate speed setting via dts for special devices
  i2c: mediatek: modify bus speed calculation formula

 .../devicetree/bindings/i2c/i2c-mt65xx.txt    |   2 +
 drivers/i2c/busses/i2c-mt65xx.c               | 192 ++++++++++++++++--
 2 files changed, 180 insertions(+), 14 deletions(-)

--
2.18.0

[PATCH v8 1/5] i2c: mediatek: Reset the handshake signal between i2c and dma

[Kewei Xu]

Due to changes in the hardware design of the handshaking signal
between i2c and dma, it is necessary to reset the handshaking
signal before each transfer to ensure that the multi-msgs can
be transferred correctly.

Signed-off-by: Kewei Xu <kewei.xu@mediatek.com>
Reviewed-by: Qii Wang <qii.wang@mediatek.com>
---
 drivers/i2c/busses/i2c-mt65xx.c | 26 ++++++++++++++++++++++++++
 1 file changed, 26 insertions(+)

diff --git a/drivers/i2c/busses/i2c-mt65xx.c b/drivers/i2c/busses/i2c-mt65xx.c
index 72acda59eb39..dad3a85cd499 100644
--- a/drivers/i2c/busses/i2c-mt65xx.c
+++ b/drivers/i2c/busses/i2c-mt65xx.c
@@ -15,6 +15,7 @@
 #include <linux/init.h>
 #include <linux/interrupt.h>
 #include <linux/io.h>
+#include <linux/iopoll.h>
 #include <linux/kernel.h>
 #include <linux/mm.h>
 #include <linux/module.h>
@@ -49,6 +50,8 @@
 #define I2C_RD_TRANAC_VALUE		0x0001
 #define I2C_SCL_MIS_COMP_VALUE		0x0000
 #define I2C_CHN_CLR_FLAG		0x0000
+#define I2C_RELIABILITY		0x0010
+#define I2C_DMAACK_ENABLE		0x0008
 
 #define I2C_DMA_CON_TX			0x0000
 #define I2C_DMA_CON_RX			0x0001
@@ -851,6 +854,7 @@ static int mtk_i2c_do_transfer(struct mtk_i2c *i2c, struct i2c_msg *msgs,
 	u16 restart_flag = 0;
 	u16 dma_sync = 0;
 	u32 reg_4g_mode;
+	u32 reg_dma_reset;
 	u8 *dma_rd_buf = NULL;
 	u8 *dma_wr_buf = NULL;
 	dma_addr_t rpaddr = 0;
@@ -864,6 +868,28 @@ static int mtk_i2c_do_transfer(struct mtk_i2c *i2c, struct i2c_msg *msgs,
 
 	reinit_completion(&i2c->msg_complete);
 
+	if (i2c->dev_comp->apdma_sync &&
+	    i2c->op != I2C_MASTER_WRRD && num > 1) {
+		mtk_i2c_writew(i2c, 0x00, OFFSET_DEBUGCTRL);
+		writel(I2C_DMA_HANDSHAKE_RST | I2C_DMA_WARM_RST,
+		       i2c->pdmabase + OFFSET_RST);
+
+		ret = readw_poll_timeout(i2c->pdmabase + OFFSET_RST,
+					 reg_dma_reset,
+					 !(reg_dma_reset & I2C_DMA_WARM_RST),
+					 0, 100);
+		if (ret) {
+			dev_err(i2c->dev, "DMA warm reset timeout\n");
+			return -ETIMEDOUT;
+		}
+
+		writel(I2C_DMA_CLR_FLAG, i2c->pdmabase + OFFSET_RST);
+		mtk_i2c_writew(i2c, I2C_HANDSHAKE_RST, OFFSET_SOFTRESET);
+		mtk_i2c_writew(i2c, I2C_CHN_CLR_FLAG, OFFSET_SOFTRESET);
+		mtk_i2c_writew(i2c, I2C_RELIABILITY | I2C_DMAACK_ENABLE,
+			       OFFSET_DEBUGCTRL);
+	}
+
 	control_reg = mtk_i2c_readw(i2c, OFFSET_CONTROL) &
 			~(I2C_CONTROL_DIR_CHANGE | I2C_CONTROL_RS);
 	if ((i2c->speed_hz > I2C_MAX_FAST_MODE_PLUS_FREQ) || (left_num >= 1))
-- 
2.25.1

Re: [PATCH v8 1/5] i2c: mediatek: Reset the handshake signal between i2c and dma

[Wolfram Sang]

[-- Attachment #1: Type: text/plain, Size: 423 bytes --]

On Sun, Oct 10, 2021 at 03:05:12PM +0800, Kewei Xu wrote:
> Due to changes in the hardware design of the handshaking signal
> between i2c and dma, it is necessary to reset the handshaking
> signal before each transfer to ensure that the multi-msgs can
> be transferred correctly.
> 
> Signed-off-by: Kewei Xu <kewei.xu@mediatek.com>
> Reviewed-by: Qii Wang <qii.wang@mediatek.com>

Applied to for-next, thanks!


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[PATCH v8 2/5] i2c: mediatek: Dump i2c/dma register when a timeout occurs

[Kewei Xu]

When a timeout error occurs in i2c transter, it is usually related
to the i2c/dma IP hardware configuration. Therefore, the purpose of
this patch is to dump the key register values of i2c/dma when a
timeout occurs in i2c for debugging.

Signed-off-by: Kewei Xu <kewei.xu@mediatek.com>
Reviewed-by: Qii Wang <qii.wang@mediatek.com>
---
 drivers/i2c/busses/i2c-mt65xx.c | 54 +++++++++++++++++++++++++++++++++
 1 file changed, 54 insertions(+)

diff --git a/drivers/i2c/busses/i2c-mt65xx.c b/drivers/i2c/busses/i2c-mt65xx.c
index dad3a85cd499..a1a2af066704 100644
--- a/drivers/i2c/busses/i2c-mt65xx.c
+++ b/drivers/i2c/busses/i2c-mt65xx.c
@@ -130,6 +130,7 @@ enum I2C_REGS_OFFSET {
 	OFFSET_HS,
 	OFFSET_SOFTRESET,
 	OFFSET_DCM_EN,
+	OFFSET_MULTI_DMA,
 	OFFSET_PATH_DIR,
 	OFFSET_DEBUGSTAT,
 	OFFSET_DEBUGCTRL,
@@ -197,6 +198,7 @@ static const u16 mt_i2c_regs_v2[] = {
 	[OFFSET_TRANSFER_LEN_AUX] = 0x44,
 	[OFFSET_CLOCK_DIV] = 0x48,
 	[OFFSET_SOFTRESET] = 0x50,
+	[OFFSET_MULTI_DMA] = 0x8c,
 	[OFFSET_SCL_MIS_COMP_POINT] = 0x90,
 	[OFFSET_DEBUGSTAT] = 0xe4,
 	[OFFSET_DEBUGCTRL] = 0xe8,
@@ -845,6 +847,57 @@ static int mtk_i2c_set_speed(struct mtk_i2c *i2c, unsigned int parent_clk)
 	return 0;
 }
 
+static void i2c_dump_register(struct mtk_i2c *i2c)
+{
+	dev_dbg(i2c->dev, "SLAVE_ADDR: 0x%x, INTR_MASK: 0x%x\n",
+		mtk_i2c_readw(i2c, OFFSET_SLAVE_ADDR),
+		mtk_i2c_readw(i2c, OFFSET_INTR_MASK));
+	dev_dbg(i2c->dev, "INTR_STAT: 0x%x, CONTROL: 0x%x\n",
+		mtk_i2c_readw(i2c, OFFSET_INTR_STAT),
+		mtk_i2c_readw(i2c, OFFSET_CONTROL));
+	dev_dbg(i2c->dev, "TRANSFER_LEN: 0x%x, TRANSAC_LEN: 0x%x\n",
+		mtk_i2c_readw(i2c, OFFSET_TRANSFER_LEN),
+		mtk_i2c_readw(i2c, OFFSET_TRANSAC_LEN));
+	dev_dbg(i2c->dev, "DELAY_LEN: 0x%x, HTIMING: 0x%x\n",
+		mtk_i2c_readw(i2c, OFFSET_DELAY_LEN),
+		mtk_i2c_readw(i2c, OFFSET_TIMING));
+	dev_dbg(i2c->dev, "START: 0x%x, EXT_CONF: 0x%x\n",
+		mtk_i2c_readw(i2c, OFFSET_START),
+		mtk_i2c_readw(i2c, OFFSET_EXT_CONF));
+	dev_dbg(i2c->dev, "HS: 0x%x, IO_CONFIG: 0x%x\n",
+		mtk_i2c_readw(i2c, OFFSET_HS),
+		mtk_i2c_readw(i2c, OFFSET_IO_CONFIG));
+	dev_dbg(i2c->dev, "DCM_EN: 0x%x, TRANSFER_LEN_AUX: 0x%x\n",
+		mtk_i2c_readw(i2c, OFFSET_DCM_EN),
+		mtk_i2c_readw(i2c, OFFSET_TRANSFER_LEN_AUX));
+	dev_dbg(i2c->dev, "CLOCK_DIV: 0x%x, FIFO_STAT: 0x%x\n",
+		mtk_i2c_readw(i2c, OFFSET_CLOCK_DIV),
+		mtk_i2c_readw(i2c, OFFSET_FIFO_STAT));
+	dev_dbg(i2c->dev, "DEBUGCTRL : 0x%x, DEBUGSTAT: 0x%x\n",
+		mtk_i2c_readw(i2c, OFFSET_DEBUGCTRL),
+		mtk_i2c_readw(i2c, OFFSET_DEBUGSTAT));
+	if (i2c->dev_comp->regs == mt_i2c_regs_v2) {
+		dev_dbg(i2c->dev, "LTIMING: 0x%x, MULTI_DMA: 0x%x\n",
+			mtk_i2c_readw(i2c, OFFSET_LTIMING),
+			mtk_i2c_readw(i2c, OFFSET_MULTI_DMA));
+	}
+	dev_dbg(i2c->dev, "\nDMA_INT_FLAG: 0x%x, DMA_INT_EN: 0x%x\n",
+		readl(i2c->pdmabase + OFFSET_INT_FLAG),
+		readl(i2c->pdmabase + OFFSET_INT_EN));
+	dev_dbg(i2c->dev, "DMA_EN: 0x%x, DMA_CON: 0x%x\n",
+		readl(i2c->pdmabase + OFFSET_EN),
+		readl(i2c->pdmabase + OFFSET_CON));
+	dev_dbg(i2c->dev, "DMA_TX_MEM_ADDR: 0x%x, DMA_RX_MEM_ADDR: 0x%x\n",
+		readl(i2c->pdmabase + OFFSET_TX_MEM_ADDR),
+		readl(i2c->pdmabase + OFFSET_RX_MEM_ADDR));
+	dev_dbg(i2c->dev, "DMA_TX_LEN: 0x%x, DMA_RX_LEN: 0x%x\n",
+		readl(i2c->pdmabase + OFFSET_TX_LEN),
+		readl(i2c->pdmabase + OFFSET_RX_LEN));
+	dev_dbg(i2c->dev, "DMA_TX_4G_MODE: 0x%x, DMA_RX_4G_MODE: 0x%x",
+		readl(i2c->pdmabase + OFFSET_TX_4G_MODE),
+		readl(i2c->pdmabase + OFFSET_RX_4G_MODE));
+}
+
 static int mtk_i2c_do_transfer(struct mtk_i2c *i2c, struct i2c_msg *msgs,
 			       int num, int left_num)
 {
@@ -1075,6 +1128,7 @@ static int mtk_i2c_do_transfer(struct mtk_i2c *i2c, struct i2c_msg *msgs,
 
 	if (ret == 0) {
 		dev_dbg(i2c->dev, "addr: %x, transfer timeout\n", msgs->addr);
+		i2c_dump_register(i2c);
 		mtk_i2c_init_hw(i2c);
 		return -ETIMEDOUT;
 	}
-- 
2.25.1

Re: [PATCH v8 2/5] i2c: mediatek: Dump i2c/dma register when a timeout occurs

[Wolfram Sang]

[-- Attachment #1: Type: text/plain, Size: 445 bytes --]

On Sun, Oct 10, 2021 at 03:05:13PM +0800, Kewei Xu wrote:
> When a timeout error occurs in i2c transter, it is usually related
> to the i2c/dma IP hardware configuration. Therefore, the purpose of
> this patch is to dump the key register values of i2c/dma when a
> timeout occurs in i2c for debugging.
> 
> Signed-off-by: Kewei Xu <kewei.xu@mediatek.com>
> Reviewed-by: Qii Wang <qii.wang@mediatek.com>

Applied to for-next, thanks!


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[PATCH v8 3/5] dt-bindings: i2c: add attribute use-default-timing

[Kewei Xu]

Add attribute use-default-timing for DT-binding document.

Fixes: be5ce0e97cc7 ("i2c: mediatek: Add i2c ac-timing adjust support")
Signed-off-by: Kewei Xu <kewei.xu@mediatek.com>
Acked-by: Rob Herring <robh@kernel.org>
Reviewed-by: Qii Wang <qii.wang@mediatek.com>
---
 Documentation/devicetree/bindings/i2c/i2c-mt65xx.txt | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/Documentation/devicetree/bindings/i2c/i2c-mt65xx.txt b/Documentation/devicetree/bindings/i2c/i2c-mt65xx.txt
index 5ea216ae7084..4dbb69745ff3 100644
--- a/Documentation/devicetree/bindings/i2c/i2c-mt65xx.txt
+++ b/Documentation/devicetree/bindings/i2c/i2c-mt65xx.txt
@@ -34,6 +34,8 @@ Optional properties:
     Only mt6589 and mt8135 support this feature.
   - mediatek,use-push-pull: IO config use push-pull mode.
   - vbus-supply: phandle to the regulator that provides power to SCL/SDA.
+  - mediatek,use-default-timing: use default timing calculation, no timing
+    adjustment.
 
 Example:
 
-- 
2.25.1

[PATCH v8 4/5] i2c: mediatek: Isolate speed setting via dts for special devices

[Kewei Xu]

In the commit be5ce0e97cc7 ("i2c: mediatek: Add i2c ac-timing adjust
support"), the I2C timing calculation has been revised to support
ac-timing adjustment, however that will break on some I2C components.
As a result we want to introduce a new setting "default-adjust-timing"
so those components can choose to use the old (default) timing algorithm.

Fixes: be5ce0e97cc7 ("i2c: mediatek: Add i2c ac-timing adjust support")
Signed-off-by: Kewei Xu <kewei.xu@mediatek.com>
Reviewed-by: Qii Wang <qii.wang@mediatek.com>
---
 drivers/i2c/busses/i2c-mt65xx.c | 77 +++++++++++++++++++++++++++++++--
 1 file changed, 73 insertions(+), 4 deletions(-)

diff --git a/drivers/i2c/busses/i2c-mt65xx.c b/drivers/i2c/busses/i2c-mt65xx.c
index a1a2af066704..3db4ed3f9050 100644
--- a/drivers/i2c/busses/i2c-mt65xx.c
+++ b/drivers/i2c/busses/i2c-mt65xx.c
@@ -65,6 +65,7 @@
 #define I2C_DMA_HARD_RST		0x0002
 #define I2C_DMA_HANDSHAKE_RST		0x0004
 
+#define I2C_DEFAULT_CLK_DIV		5
 #define MAX_SAMPLE_CNT_DIV		8
 #define MAX_STEP_CNT_DIV		64
 #define MAX_CLOCK_DIV			256
@@ -249,6 +250,7 @@ struct mtk_i2c {
 	struct clk *clk_arb;		/* Arbitrator clock for i2c */
 	bool have_pmic;			/* can use i2c pins from PMIC */
 	bool use_push_pull;		/* IO config push-pull mode */
+	bool use_default_timing;	/* no timing adjust mode */
 
 	u16 irq_stat;			/* interrupt status */
 	unsigned int clk_src_div;
@@ -531,7 +533,11 @@ static void mtk_i2c_init_hw(struct mtk_i2c *i2c)
 	else
 		ext_conf_val = I2C_FS_START_CON;
 
-	if (i2c->dev_comp->timing_adjust) {
+	if (i2c->use_default_timing) {
+		if (i2c->dev_comp->timing_adjust)
+			mtk_i2c_writew(i2c, I2C_DEFAULT_CLK_DIV - 1,
+				       OFFSET_CLOCK_DIV);
+	} else if (i2c->dev_comp->timing_adjust) {
 		ext_conf_val = i2c->ac_timing.ext;
 		mtk_i2c_writew(i2c, i2c->ac_timing.inter_clk_div,
 			       OFFSET_CLOCK_DIV);
@@ -614,7 +620,7 @@ static int mtk_i2c_check_ac_timing(struct mtk_i2c *i2c,
 	unsigned int sample_ns = div_u64(1000000000ULL * (sample_cnt + 1),
 					 clk_src);
 
-	if (!i2c->dev_comp->timing_adjust)
+	if (i2c->use_default_timing || !i2c->dev_comp->timing_adjust)
 		return 0;
 
 	if (i2c->dev_comp->ltiming_adjust)
@@ -774,7 +780,65 @@ static int mtk_i2c_calculate_speed(struct mtk_i2c *i2c, unsigned int clk_src,
 	return 0;
 }
 
-static int mtk_i2c_set_speed(struct mtk_i2c *i2c, unsigned int parent_clk)
+static int mtk_i2c_set_speed_default_timing(struct mtk_i2c *i2c,
+					    unsigned int parent_clk)
+{
+	unsigned int clk_src;
+	unsigned int step_cnt;
+	unsigned int sample_cnt;
+	unsigned int l_step_cnt;
+	unsigned int l_sample_cnt;
+	unsigned int target_speed;
+	int ret;
+
+	if (i2c->dev_comp->timing_adjust)
+		i2c->clk_src_div *= I2C_DEFAULT_CLK_DIV;
+
+	clk_src = parent_clk / i2c->clk_src_div;
+	target_speed = i2c->speed_hz;
+
+	if (target_speed > I2C_MAX_FAST_MODE_PLUS_FREQ) {
+		/* Set master code speed register */
+		ret = mtk_i2c_calculate_speed(i2c, clk_src,
+					      I2C_MAX_FAST_MODE_FREQ,
+					      &l_step_cnt, &l_sample_cnt);
+		if (ret < 0)
+			return ret;
+
+		i2c->timing_reg = (l_sample_cnt << 8) | l_step_cnt;
+
+		/* Set the high speed mode register */
+		ret = mtk_i2c_calculate_speed(i2c, clk_src, target_speed,
+					      &step_cnt, &sample_cnt);
+		if (ret < 0)
+			return ret;
+
+		i2c->high_speed_reg = I2C_TIME_DEFAULT_VALUE |
+			(sample_cnt << 12) | (step_cnt << 8);
+
+		if (i2c->dev_comp->ltiming_adjust)
+			i2c->ltiming_reg = (l_sample_cnt << 6) | l_step_cnt |
+					   (sample_cnt << 12) | (step_cnt << 9);
+	} else {
+		ret = mtk_i2c_calculate_speed(i2c, clk_src, target_speed,
+					      &step_cnt, &sample_cnt);
+		if (ret < 0)
+			return ret;
+
+		i2c->timing_reg = (sample_cnt << 8) | step_cnt;
+
+		/* Disable the high speed transaction */
+		i2c->high_speed_reg = I2C_TIME_CLR_VALUE;
+
+		if (i2c->dev_comp->ltiming_adjust)
+			i2c->ltiming_reg = (sample_cnt << 6) | step_cnt;
+	}
+
+	return 0;
+}
+
+static int mtk_i2c_set_speed_adjust_timing(struct mtk_i2c *i2c,
+					   unsigned int parent_clk)
 {
 	unsigned int clk_src;
 	unsigned int step_cnt;
@@ -1271,6 +1335,8 @@ static int mtk_i2c_parse_dt(struct device_node *np, struct mtk_i2c *i2c)
 	i2c->have_pmic = of_property_read_bool(np, "mediatek,have-pmic");
 	i2c->use_push_pull =
 		of_property_read_bool(np, "mediatek,use-push-pull");
+	i2c->use_default_timing =
+		of_property_read_bool(np, "mediatek,use-default-timing");
 
 	i2c_parse_fw_timings(i2c->dev, &i2c->timing_info, true);
 
@@ -1357,7 +1423,10 @@ static int mtk_i2c_probe(struct platform_device *pdev)
 
 	strlcpy(i2c->adap.name, I2C_DRV_NAME, sizeof(i2c->adap.name));
 
-	ret = mtk_i2c_set_speed(i2c, clk_get_rate(clk));
+	if (i2c->use_default_timing)
+		ret = mtk_i2c_set_speed_default_timing(i2c, clk_get_rate(clk));
+	else
+		ret = mtk_i2c_set_speed_adjust_timing(i2c, clk_get_rate(clk));
 	if (ret) {
 		dev_err(&pdev->dev, "Failed to set the speed.\n");
 		return -EINVAL;
-- 
2.25.1

[PATCH v8 5/5] i2c: mediatek: modify bus speed calculation formula

[Kewei Xu]

When clock-div is 0 or greater than 1, the bus speed
calculated by the old speed calculation formula will be
larger than the target speed. So we update the formula.

Signed-off-by: Kewei Xu <kewei.xu@mediatek.com>
Reviewed-by: Qii Wang <qii.wang@mediatek.com>
---
 drivers/i2c/busses/i2c-mt65xx.c | 35 +++++++++++++++++++++++----------
 1 file changed, 25 insertions(+), 10 deletions(-)

diff --git a/drivers/i2c/busses/i2c-mt65xx.c b/drivers/i2c/busses/i2c-mt65xx.c
index 3db4ed3f9050..ad07647f88d5 100644
--- a/drivers/i2c/busses/i2c-mt65xx.c
+++ b/drivers/i2c/busses/i2c-mt65xx.c
@@ -68,11 +68,12 @@
 #define I2C_DEFAULT_CLK_DIV		5
 #define MAX_SAMPLE_CNT_DIV		8
 #define MAX_STEP_CNT_DIV		64
-#define MAX_CLOCK_DIV			256
+#define MAX_CLOCK_DIV_8BITS		256
+#define MAX_CLOCK_DIV_5BITS		32
 #define MAX_HS_STEP_CNT_DIV		8
-#define I2C_STANDARD_MODE_BUFFER	(1000 / 2)
-#define I2C_FAST_MODE_BUFFER		(300 / 2)
-#define I2C_FAST_MODE_PLUS_BUFFER	(20 / 2)
+#define I2C_STANDARD_MODE_BUFFER	(1000 / 3)
+#define I2C_FAST_MODE_BUFFER		(300 / 3)
+#define I2C_FAST_MODE_PLUS_BUFFER	(20 / 3)
 
 #define I2C_CONTROL_RS                  (0x1 << 1)
 #define I2C_CONTROL_DMA_EN              (0x1 << 2)
@@ -724,14 +725,26 @@ static int mtk_i2c_calculate_speed(struct mtk_i2c *i2c, unsigned int clk_src,
 	unsigned int best_mul;
 	unsigned int cnt_mul;
 	int ret = -EINVAL;
+	int clock_div_constraint = 0;
 
 	if (target_speed > I2C_MAX_HIGH_SPEED_MODE_FREQ)
 		target_speed = I2C_MAX_HIGH_SPEED_MODE_FREQ;
 
+	if (i2c->use_default_timing) {
+		clock_div_constraint = 0;
+	} else if (i2c->dev_comp->ltiming_adjust &&
+		   i2c->ac_timing.inter_clk_div > 1) {
+		clock_div_constraint = 1;
+	} else if (i2c->dev_comp->ltiming_adjust &&
+		   i2c->ac_timing.inter_clk_div == 0) {
+		clock_div_constraint = -1;
+	}
+
 	max_step_cnt = mtk_i2c_max_step_cnt(target_speed);
 	base_step_cnt = max_step_cnt;
 	/* Find the best combination */
-	opt_div = DIV_ROUND_UP(clk_src >> 1, target_speed);
+	opt_div = DIV_ROUND_UP(clk_src >> 1, target_speed) +
+		  clock_div_constraint;
 	best_mul = MAX_SAMPLE_CNT_DIV * max_step_cnt;
 
 	/* Search for the best pair (sample_cnt, step_cnt) with
@@ -766,7 +779,8 @@ static int mtk_i2c_calculate_speed(struct mtk_i2c *i2c, unsigned int clk_src,
 	sample_cnt = base_sample_cnt;
 	step_cnt = base_step_cnt;
 
-	if ((clk_src / (2 * sample_cnt * step_cnt)) > target_speed) {
+	if ((clk_src / (2 * (sample_cnt * step_cnt - clock_div_constraint))) >
+		 target_speed) {
 		/* In this case, hardware can't support such
 		 * low i2c_bus_freq
 		 */
@@ -853,13 +867,16 @@ static int mtk_i2c_set_speed_adjust_timing(struct mtk_i2c *i2c,
 	target_speed = i2c->speed_hz;
 	parent_clk /= i2c->clk_src_div;
 
-	if (i2c->dev_comp->timing_adjust)
-		max_clk_div = MAX_CLOCK_DIV;
+	if (i2c->dev_comp->timing_adjust && i2c->dev_comp->ltiming_adjust)
+		max_clk_div = MAX_CLOCK_DIV_5BITS;
+	else if (i2c->dev_comp->timing_adjust)
+		max_clk_div = MAX_CLOCK_DIV_8BITS;
 	else
 		max_clk_div = 1;
 
 	for (clk_div = 1; clk_div <= max_clk_div; clk_div++) {
 		clk_src = parent_clk / clk_div;
+		i2c->ac_timing.inter_clk_div = clk_div - 1;
 
 		if (target_speed > I2C_MAX_FAST_MODE_PLUS_FREQ) {
 			/* Set master code speed register */
@@ -906,8 +923,6 @@ static int mtk_i2c_set_speed_adjust_timing(struct mtk_i2c *i2c,
 		break;
 	}
 
-	i2c->ac_timing.inter_clk_div = clk_div - 1;
-
 	return 0;
 }
 
-- 
2.25.1