[PATCH v4 00/10] i2c: meson: series with improvements

[PATCH v4 00/10] i2c: meson: series with improvements

[Heiner Kallweit]

This patch series includes several improvements for the i2c-meson
driver.

Changes in v2:
- removed patches 8 and 12
- removed one small change in patch 6
- don't print error message in patch 7

Changes in v3:
- changed order of patches 3, 4, 5 what makes the patches more simple
- remove one change from patch 7 to still properly deal with timeouts

Changes in v4:
- update DT binding documentation as part of patch 4

Heiner Kallweit (12):
  i2c: meson: use min instead of min_t where min_t isn't needed
  i2c: meson: remove member irq from struct meson_i2c
  i2c: meson: set clock divider in probe instead of setting it for each transfer
  i2c: meson: use i2c core for DT clock-frequency parsing
  i2c: meson: use full 12 bits for clock divider
  i2c: meson: remove variable count from meson_i2c_xfer
  i2c: meson: improve interrupt handler and detect spurious interrupts
  i2c: meson: don't create separate token chain just for the stop command
  i2c: meson: remove meson_i2c_write_tokens
  i2c: meson: improve and simplify interrupt handler

 Documentation/devicetree/bindings/i2c/i2c-meson.txt |  17 +++++++++++++++++
 drivers/i2c/busses/i2c-meson.c                      | 132 ++++++++++++++++-------------------------
 2 file changed, 67 insertions(+), 82 deletions(-)

-- 
2.12.0

[PATCH v4 01/10] i2c: meson: use min instead of min_t where min_t isn't needed

[Heiner Kallweit]

Use min instead of min_t where min_t isn't needed.

Signed-off-by: Heiner Kallweit <hkallweit1@gmail.com>
---
v2:
- no changes
v3:
- no changes
v4:
- no changes
---
 drivers/i2c/busses/i2c-meson.c | 10 +++++-----
 1 file changed, 5 insertions(+), 5 deletions(-)

diff --git a/drivers/i2c/busses/i2c-meson.c b/drivers/i2c/busses/i2c-meson.c
index 73b97c71..40e5da9a 100644
--- a/drivers/i2c/busses/i2c-meson.c
+++ b/drivers/i2c/busses/i2c-meson.c
@@ -156,10 +156,10 @@ static void meson_i2c_get_data(struct meson_i2c *i2c, char *buf, int len)
 	dev_dbg(i2c->dev, "%s: data %08x %08x len %d\n", __func__,
 		rdata0, rdata1, len);
 
-	for (i = 0; i < min_t(int, 4, len); i++)
+	for (i = 0; i < min(4, len); i++)
 		*buf++ = (rdata0 >> i * 8) & 0xff;
 
-	for (i = 4; i < min_t(int, 8, len); i++)
+	for (i = 4; i < min(8, len); i++)
 		*buf++ = (rdata1 >> (i - 4) * 8) & 0xff;
 }
 
@@ -168,10 +168,10 @@ static void meson_i2c_put_data(struct meson_i2c *i2c, char *buf, int len)
 	u32 wdata0 = 0, wdata1 = 0;
 	int i;
 
-	for (i = 0; i < min_t(int, 4, len); i++)
+	for (i = 0; i < min(4, len); i++)
 		wdata0 |= *buf++ << (i * 8);
 
-	for (i = 4; i < min_t(int, 8, len); i++)
+	for (i = 4; i < min(8, len); i++)
 		wdata1 |= *buf++ << ((i - 4) * 8);
 
 	writel(wdata0, i2c->regs + REG_TOK_WDATA0);
@@ -186,7 +186,7 @@ static void meson_i2c_prepare_xfer(struct meson_i2c *i2c)
 	bool write = !(i2c->msg->flags & I2C_M_RD);
 	int i;
 
-	i2c->count = min_t(int, i2c->msg->len - i2c->pos, 8);
+	i2c->count = min(i2c->msg->len - i2c->pos, 8);
 
 	for (i = 0; i < i2c->count - 1; i++)
 		meson_i2c_add_token(i2c, TOKEN_DATA);
-- 
2.12.0

[PATCH v4 02/10] i2c: meson: remove member irq from struct meson_i2c

[Heiner Kallweit]

Member irq can be replaced with a local variable in probe
because it's nowhere else accessed.

Signed-off-by: Heiner Kallweit <hkallweit1@gmail.com>
Reviewed-by: Jerome Brunet <jbrunet@baylibre.com>
---
v2:
- added Reviewed-by
v3:
- no changes
v4:
- no changes
---
 drivers/i2c/busses/i2c-meson.c | 13 ++++++-------
 1 file changed, 6 insertions(+), 7 deletions(-)

diff --git a/drivers/i2c/busses/i2c-meson.c b/drivers/i2c/busses/i2c-meson.c
index 40e5da9a..50059d09 100644
--- a/drivers/i2c/busses/i2c-meson.c
+++ b/drivers/i2c/busses/i2c-meson.c
@@ -82,7 +82,6 @@ struct meson_i2c {
 	struct device		*dev;
 	void __iomem		*regs;
 	struct clk		*clk;
-	int			irq;
 
 	struct i2c_msg		*msg;
 	int			state;
@@ -391,7 +390,7 @@ static int meson_i2c_probe(struct platform_device *pdev)
 	struct device_node *np = pdev->dev.of_node;
 	struct meson_i2c *i2c;
 	struct resource *mem;
-	int ret = 0;
+	int irq, ret = 0;
 
 	i2c = devm_kzalloc(&pdev->dev, sizeof(struct meson_i2c), GFP_KERNEL);
 	if (!i2c)
@@ -418,14 +417,14 @@ static int meson_i2c_probe(struct platform_device *pdev)
 	if (IS_ERR(i2c->regs))
 		return PTR_ERR(i2c->regs);
 
-	i2c->irq = platform_get_irq(pdev, 0);
-	if (i2c->irq < 0) {
+	irq = platform_get_irq(pdev, 0);
+	if (irq < 0) {
 		dev_err(&pdev->dev, "can't find IRQ\n");
-		return i2c->irq;
+		return irq;
 	}
 
-	ret = devm_request_irq(&pdev->dev, i2c->irq, meson_i2c_irq,
-			       0, dev_name(&pdev->dev), i2c);
+	ret = devm_request_irq(&pdev->dev, irq, meson_i2c_irq, 0,
+			       dev_name(&pdev->dev), i2c);
 	if (ret < 0) {
 		dev_err(&pdev->dev, "can't request IRQ\n");
 		return ret;
-- 
2.12.0

[PATCH v4 04/10] i2c: meson: use i2c core for DT clock-frequency parsing

[Heiner Kallweit]

We don't have to parse the DT manually to retrieve the bus frequency
and we don't have to maintain an own default for the bus frequency.
Let the i2c core do this for us.

Signed-off-by: Heiner Kallweit <hkallweit1@gmail.com>
Reviewed-by: Jerome Brunet <jbrunet@baylibre.com>
---
v2:
- added Reviewed-by
v3:
- changed order of patches
v4:
- update DT binding documentation
---
 Documentation/devicetree/bindings/i2c/i2c-meson.txt | 17 +++++++++++++++++
 drivers/i2c/busses/i2c-meson.c                      |  8 +++-----
 2 files changed, 20 insertions(+), 5 deletions(-)

diff --git a/Documentation/devicetree/bindings/i2c/i2c-meson.txt b/Documentation/devicetree/bindings/i2c/i2c-meson.txt
index 386357d1..6bc10cdc 100644
--- a/Documentation/devicetree/bindings/i2c/i2c-meson.txt
+++ b/Documentation/devicetree/bindings/i2c/i2c-meson.txt
@@ -8,10 +8,27 @@ Required properties:
  - #address-cells: should be <1>
  - #size-cells: should be <0>
 
+For details regarding the following core I2C bindings see also i2c.txt.
+
 Optional properties:
 - clock-frequency: the desired I2C bus clock frequency in Hz; in
   absence of this property the default value is used (100 kHz).
 
+- i2c-scl-falling-time-ns
+  Number of nanoseconds the SCL signal takes to fall; t(f) in the I2C
+  specification.
+
+- i2c-scl-internal-delay-ns
+  Number of nanoseconds the IP core additionally needs to setup SCL.
+
+- i2c-scl-rising-time-ns
+  Number of nanoseconds the SCL signal takes to rise; t(r) in the I2C
+  specification.
+
+- i2c-sda-falling-time-ns
+  Number of nanoseconds the SDA signal takes to fall; t(f) in the I2C
+  specification.
+
 Examples:
 
 	i2c@c8100500 {
diff --git a/drivers/i2c/busses/i2c-meson.c b/drivers/i2c/busses/i2c-meson.c
index e597764e..ac0ac82d 100644
--- a/drivers/i2c/busses/i2c-meson.c
+++ b/drivers/i2c/busses/i2c-meson.c
@@ -38,7 +38,6 @@
 #define REG_CTRL_CLKDIV_MASK	((BIT(10) - 1) << REG_CTRL_CLKDIV_SHIFT)
 
 #define I2C_TIMEOUT_MS		500
-#define DEFAULT_FREQ		100000
 
 enum {
 	TOKEN_END = 0,
@@ -387,15 +386,14 @@ static int meson_i2c_probe(struct platform_device *pdev)
 	struct device_node *np = pdev->dev.of_node;
 	struct meson_i2c *i2c;
 	struct resource *mem;
-	u32 freq;
+	struct i2c_timings timings;
 	int irq, ret = 0;
 
 	i2c = devm_kzalloc(&pdev->dev, sizeof(struct meson_i2c), GFP_KERNEL);
 	if (!i2c)
 		return -ENOMEM;
 
-	if (of_property_read_u32(pdev->dev.of_node, "clock-frequency", &freq))
-		freq = DEFAULT_FREQ;
+	i2c_parse_fw_timings(&pdev->dev, &timings, true);
 
 	i2c->dev = &pdev->dev;
 	platform_set_drvdata(pdev, i2c);
@@ -453,7 +451,7 @@ static int meson_i2c_probe(struct platform_device *pdev)
 		return ret;
 	}
 
-	meson_i2c_set_clk_div(i2c, freq);
+	meson_i2c_set_clk_div(i2c, timings.bus_freq_hz);
 
 	return 0;
 }
-- 
2.12.0

Re: [PATCH v4 04/10] i2c: meson: use i2c core for DT clock-frequency parsing

[Wolfram Sang]

[-- Attachment #1: Type: text/plain, Size: 604 bytes --]


> +- i2c-scl-falling-time-ns
> +  Number of nanoseconds the SCL signal takes to fall; t(f) in the I2C
> +  specification.
> +
> +- i2c-scl-internal-delay-ns
> +  Number of nanoseconds the IP core additionally needs to setup SCL.
> +
> +- i2c-scl-rising-time-ns
> +  Number of nanoseconds the SCL signal takes to rise; t(r) in the I2C
> +  specification.
> +
> +- i2c-sda-falling-time-ns
> +  Number of nanoseconds the SDA signal takes to fall; t(f) in the I2C
> +  specification.

Those are not used currently. Can the driver be updated to make use of
them? Otherwise, we might just skip this section.


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Re: [PATCH v4 04/10] i2c: meson: use i2c core for DT clock-frequency parsing

[Heiner Kallweit]

Am 23.03.2017 um 21:33 schrieb Wolfram Sang:
> 
>> +- i2c-scl-falling-time-ns
>> +  Number of nanoseconds the SCL signal takes to fall; t(f) in the I2C
>> +  specification.
>> +
>> +- i2c-scl-internal-delay-ns
>> +  Number of nanoseconds the IP core additionally needs to setup SCL.
>> +
>> +- i2c-scl-rising-time-ns
>> +  Number of nanoseconds the SCL signal takes to rise; t(r) in the I2C
>> +  specification.
>> +
>> +- i2c-sda-falling-time-ns
>> +  Number of nanoseconds the SDA signal takes to fall; t(f) in the I2C
>> +  specification.
> 
> Those are not used currently. Can the driver be updated to make use of
> them? Otherwise, we might just skip this section.
> 
Adding these properties was outcome of a discussion with Amlogic
maintainers. It's right that they aren't used by the driver and the
chip also provides no means to change the related timings.
So I will remove this part.

[PATCH v4 05/10] i2c: meson: use full 12 bits for clock divider

[Heiner Kallweit]

The clock divider has 12 bits, splitted into a 10 bit field and a
2 bit field. The extra 2 bits aren't used currently.

Change this to use the full 12 bits and warn if the requested
frequency is too low.

Signed-off-by: Heiner Kallweit <hkallweit1@gmail.com>
Acked-by: Jerome Brunet <jbrunet@baylibre.com>
---
v2:
- added Acked-by
v3:
- changed order of patches
v4:
- no changes
---
 drivers/i2c/busses/i2c-meson.c | 13 +++++++++++--
 1 file changed, 11 insertions(+), 2 deletions(-)

diff --git a/drivers/i2c/busses/i2c-meson.c b/drivers/i2c/busses/i2c-meson.c
index ac0ac82d..03f70282 100644
--- a/drivers/i2c/busses/i2c-meson.c
+++ b/drivers/i2c/busses/i2c-meson.c
@@ -35,7 +35,9 @@
 #define REG_CTRL_STATUS		BIT(2)
 #define REG_CTRL_ERROR		BIT(3)
 #define REG_CTRL_CLKDIV_SHIFT	12
-#define REG_CTRL_CLKDIV_MASK	((BIT(10) - 1) << REG_CTRL_CLKDIV_SHIFT)
+#define REG_CTRL_CLKDIV_MASK	GENMASK(21, 12)
+#define REG_CTRL_CLKDIVEXT_SHIFT 28
+#define REG_CTRL_CLKDIVEXT_MASK	GENMASK(29, 28)
 
 #define I2C_TIMEOUT_MS		500
 
@@ -134,8 +136,15 @@ static void meson_i2c_set_clk_div(struct meson_i2c *i2c, unsigned int freq)
 	unsigned int div;
 
 	div = DIV_ROUND_UP(clk_rate, freq * 4);
+
+	/* clock divider has 12 bits */
+	WARN_ON(div >= (1 << 12));
+
 	meson_i2c_set_mask(i2c, REG_CTRL, REG_CTRL_CLKDIV_MASK,
-			   div << REG_CTRL_CLKDIV_SHIFT);
+			   (div & GENMASK(9, 0)) << REG_CTRL_CLKDIV_SHIFT);
+
+	meson_i2c_set_mask(i2c, REG_CTRL, REG_CTRL_CLKDIVEXT_MASK,
+			   (div >> 10) << REG_CTRL_CLKDIVEXT_SHIFT);
 
 	dev_dbg(i2c->dev, "%s: clk %lu, freq %u, div %u\n", __func__,
 		clk_rate, freq, div);
-- 
2.12.0

Re: [PATCH v4 05/10] i2c: meson: use full 12 bits for clock divider

[Wolfram Sang]

[-- Attachment #1: Type: text/plain, Size: 133 bytes --]


> +	/* clock divider has 12 bits */
> +	WARN_ON(div >= (1 << 12));

Do you insist on WARN_ON? I wonder what it gives over dev_err?


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Re: [PATCH v4 05/10] i2c: meson: use full 12 bits for clock divider

[Heiner Kallweit]

Am 23.03.2017 um 21:34 schrieb Wolfram Sang:
> 
>> +	/* clock divider has 12 bits */
>> +	WARN_ON(div >= (1 << 12));
> 
> Do you insist on WARN_ON? I wonder what it gives over dev_err?
> 
Right, as we just read the bus frequency from DT there's not
really a benefit in seeing the call trace. I'll change it.

[PATCH v4 06/10] i2c: meson: remove variable count from meson_i2c_xfer

[Heiner Kallweit]

Variable count has always the same value as i, so we don't need it.

Signed-off-by: Heiner Kallweit <hkallweit1@gmail.com>
---
v2:
- remove one small change from v1
v3:
- no changes
v4:
- no changes
---
 drivers/i2c/busses/i2c-meson.c | 5 ++---
 1 file changed, 2 insertions(+), 3 deletions(-)

diff --git a/drivers/i2c/busses/i2c-meson.c b/drivers/i2c/busses/i2c-meson.c
index 03f70282..3fc1a715 100644
--- a/drivers/i2c/busses/i2c-meson.c
+++ b/drivers/i2c/busses/i2c-meson.c
@@ -364,7 +364,7 @@ static int meson_i2c_xfer(struct i2c_adapter *adap, struct i2c_msg *msgs,
 			  int num)
 {
 	struct meson_i2c *i2c = adap->algo_data;
-	int i, ret = 0, count = 0;
+	int i, ret = 0;
 
 	clk_enable(i2c->clk);
 
@@ -372,12 +372,11 @@ static int meson_i2c_xfer(struct i2c_adapter *adap, struct i2c_msg *msgs,
 		ret = meson_i2c_xfer_msg(i2c, msgs + i, i == num - 1);
 		if (ret)
 			break;
-		count++;
 	}
 
 	clk_disable(i2c->clk);
 
-	return ret ? ret : count;
+	return ret ?: i;
 }
 
 static u32 meson_i2c_func(struct i2c_adapter *adap)
-- 
2.12.0

[PATCH v4 07/10] i2c: meson: improve interrupt handler and detect spurious interrupts

[Heiner Kallweit]

If state is STATE_IDLE no interrupt should occur. Return IRQ_NONE
if such a spurious interrupt is detected.
Not having to take care of STATE_IDLE later in the interrupt handler
allows to further simplify the interrupt handler in subsequent
patches of this series.

In addition move resetting REG_CTRL_START bit to the start of the
interrupt handler to ensure that the start bit is always reset.
Currently the start bit is not reset for STATE_STOP because
i2c->state is set to STATE_IDLE.

Signed-off-by: Heiner Kallweit <hkallweit1@gmail.com>
---
v2:
- don't print an error if spurious interrupt is detected
v3:
- don't remove a start bit reset, we need it to properly handle timeouts
- extend commit message
v4:
- no changes
---
 drivers/i2c/busses/i2c-meson.c | 11 +++++++----
 1 file changed, 7 insertions(+), 4 deletions(-)

diff --git a/drivers/i2c/busses/i2c-meson.c b/drivers/i2c/busses/i2c-meson.c
index 3fc1a715..0b09e059 100644
--- a/drivers/i2c/busses/i2c-meson.c
+++ b/drivers/i2c/busses/i2c-meson.c
@@ -228,12 +228,18 @@ static irqreturn_t meson_i2c_irq(int irqno, void *dev_id)
 	spin_lock(&i2c->lock);
 
 	meson_i2c_reset_tokens(i2c);
+	meson_i2c_set_mask(i2c, REG_CTRL, REG_CTRL_START, 0);
 	ctrl = readl(i2c->regs + REG_CTRL);
 
 	dev_dbg(i2c->dev, "irq: state %d, pos %d, count %d, ctrl %08x\n",
 		i2c->state, i2c->pos, i2c->count, ctrl);
 
-	if (ctrl & REG_CTRL_ERROR && i2c->state != STATE_IDLE) {
+	if (i2c->state == STATE_IDLE) {
+		spin_unlock(&i2c->lock);
+		return IRQ_NONE;
+	}
+
+	if (ctrl & REG_CTRL_ERROR) {
 		/*
 		 * The bit is set when the IGNORE_NAK bit is cleared
 		 * and the device didn't respond. In this case, the
@@ -276,15 +282,12 @@ static irqreturn_t meson_i2c_irq(int irqno, void *dev_id)
 		i2c->state = STATE_IDLE;
 		complete(&i2c->done);
 		break;
-	case STATE_IDLE:
-		break;
 	}
 
 out:
 	if (i2c->state != STATE_IDLE) {
 		/* Restart the processing */
 		meson_i2c_write_tokens(i2c);
-		meson_i2c_set_mask(i2c, REG_CTRL, REG_CTRL_START, 0);
 		meson_i2c_set_mask(i2c, REG_CTRL, REG_CTRL_START,
 				   REG_CTRL_START);
 	}
-- 
2.12.0

[PATCH v4 08/10] i2c: meson: don't create separate token chain just for the stop command

[Heiner Kallweit]

We can directly add the stop token to the token chain including the
last transfer chunk. This is more efficient than creating a separate
token chain just for the stop command.
And it allows us to get rid of state STATE_STOP completely.

Signed-off-by: Heiner Kallweit <hkallweit1@gmail.com>
---
v2:
- rebased
v3:
- no changes
v4:
- no changes
---
 drivers/i2c/busses/i2c-meson.c | 23 +++++------------------
 1 file changed, 5 insertions(+), 18 deletions(-)

diff --git a/drivers/i2c/busses/i2c-meson.c b/drivers/i2c/busses/i2c-meson.c
index 0b09e059..6c873ed8 100644
--- a/drivers/i2c/busses/i2c-meson.c
+++ b/drivers/i2c/busses/i2c-meson.c
@@ -55,7 +55,6 @@ enum {
 	STATE_IDLE,
 	STATE_READ,
 	STATE_WRITE,
-	STATE_STOP,
 };
 
 /**
@@ -205,19 +204,9 @@ static void meson_i2c_prepare_xfer(struct meson_i2c *i2c)
 
 	if (write)
 		meson_i2c_put_data(i2c, i2c->msg->buf + i2c->pos, i2c->count);
-}
-
-static void meson_i2c_stop(struct meson_i2c *i2c)
-{
-	dev_dbg(i2c->dev, "%s: last %d\n", __func__, i2c->last);
 
-	if (i2c->last) {
-		i2c->state = STATE_STOP;
+	if (i2c->last && i2c->pos + i2c->count >= i2c->msg->len)
 		meson_i2c_add_token(i2c, TOKEN_STOP);
-	} else {
-		i2c->state = STATE_IDLE;
-		complete(&i2c->done);
-	}
 }
 
 static irqreturn_t meson_i2c_irq(int irqno, void *dev_id)
@@ -262,7 +251,8 @@ static irqreturn_t meson_i2c_irq(int irqno, void *dev_id)
 		}
 
 		if (i2c->pos >= i2c->msg->len) {
-			meson_i2c_stop(i2c);
+			i2c->state = STATE_IDLE;
+			complete(&i2c->done);
 			break;
 		}
 
@@ -272,16 +262,13 @@ static irqreturn_t meson_i2c_irq(int irqno, void *dev_id)
 		i2c->pos += i2c->count;
 
 		if (i2c->pos >= i2c->msg->len) {
-			meson_i2c_stop(i2c);
+			i2c->state = STATE_IDLE;
+			complete(&i2c->done);
 			break;
 		}
 
 		meson_i2c_prepare_xfer(i2c);
 		break;
-	case STATE_STOP:
-		i2c->state = STATE_IDLE;
-		complete(&i2c->done);
-		break;
 	}
 
 out:
-- 
2.12.0

[PATCH v4 09/10] i2c: meson: remove meson_i2c_write_tokens

[Heiner Kallweit]

meson_i2c_write_tokens is always called directly after
meson_i2c_prepare_xfer (and only then). So we can simplify the code by
removing meson_i2c_write_tokens and moving the two statements of
meson_i2c_write_tokens to the end of meson_i2c_prepare_xfer. 

Signed-off-by: Heiner Kallweit <hkallweit1@gmail.com>
---
v2:
- rebased
v3:
- no changes
v4:
- no changes
---
 drivers/i2c/busses/i2c-meson.c | 14 ++++----------
 1 file changed, 4 insertions(+), 10 deletions(-)

diff --git a/drivers/i2c/busses/i2c-meson.c b/drivers/i2c/busses/i2c-meson.c
index 6c873ed8..23f25efa 100644
--- a/drivers/i2c/busses/i2c-meson.c
+++ b/drivers/i2c/busses/i2c-meson.c
@@ -123,12 +123,6 @@ static void meson_i2c_add_token(struct meson_i2c *i2c, int token)
 	i2c->num_tokens++;
 }
 
-static void meson_i2c_write_tokens(struct meson_i2c *i2c)
-{
-	writel(i2c->tokens[0], i2c->regs + REG_TOK_LIST0);
-	writel(i2c->tokens[1], i2c->regs + REG_TOK_LIST1);
-}
-
 static void meson_i2c_set_clk_div(struct meson_i2c *i2c, unsigned int freq)
 {
 	unsigned long clk_rate = clk_get_rate(i2c->clk);
@@ -207,6 +201,9 @@ static void meson_i2c_prepare_xfer(struct meson_i2c *i2c)
 
 	if (i2c->last && i2c->pos + i2c->count >= i2c->msg->len)
 		meson_i2c_add_token(i2c, TOKEN_STOP);
+
+	writel(i2c->tokens[0], i2c->regs + REG_TOK_LIST0);
+	writel(i2c->tokens[1], i2c->regs + REG_TOK_LIST1);
 }
 
 static irqreturn_t meson_i2c_irq(int irqno, void *dev_id)
@@ -272,12 +269,10 @@ static irqreturn_t meson_i2c_irq(int irqno, void *dev_id)
 	}
 
 out:
-	if (i2c->state != STATE_IDLE) {
+	if (i2c->state != STATE_IDLE)
 		/* Restart the processing */
-		meson_i2c_write_tokens(i2c);
 		meson_i2c_set_mask(i2c, REG_CTRL, REG_CTRL_START,
 				   REG_CTRL_START);
-	}
 
 	spin_unlock(&i2c->lock);
 
@@ -318,7 +313,6 @@ static int meson_i2c_xfer_msg(struct meson_i2c *i2c, struct i2c_msg *msg,
 
 	i2c->state = (msg->flags & I2C_M_RD) ? STATE_READ : STATE_WRITE;
 	meson_i2c_prepare_xfer(i2c);
-	meson_i2c_write_tokens(i2c);
 	reinit_completion(&i2c->done);
 
 	/* Start the transfer */
-- 
2.12.0

[PATCH v4 10/10] i2c: meson: improve and simplify interrupt handler

[Heiner Kallweit]

The preceding changes in this patch series now allow to simplify
the interrupt handler significantly.

Signed-off-by: Heiner Kallweit <hkallweit1@gmail.com>
---
v2:
- rebased
v3:
- no changes
v4:
- no changes
---
 drivers/i2c/busses/i2c-meson.c | 40 ++++++++++------------------------------
 1 file changed, 10 insertions(+), 30 deletions(-)

diff --git a/drivers/i2c/busses/i2c-meson.c b/drivers/i2c/busses/i2c-meson.c
index 23f25efa..590715ae 100644
--- a/drivers/i2c/busses/i2c-meson.c
+++ b/drivers/i2c/busses/i2c-meson.c
@@ -239,41 +239,21 @@ static irqreturn_t meson_i2c_irq(int irqno, void *dev_id)
 		goto out;
 	}
 
-	switch (i2c->state) {
-	case STATE_READ:
-		if (i2c->count > 0) {
-			meson_i2c_get_data(i2c, i2c->msg->buf + i2c->pos,
-					   i2c->count);
-			i2c->pos += i2c->count;
-		}
-
-		if (i2c->pos >= i2c->msg->len) {
-			i2c->state = STATE_IDLE;
-			complete(&i2c->done);
-			break;
-		}
-
-		meson_i2c_prepare_xfer(i2c);
-		break;
-	case STATE_WRITE:
-		i2c->pos += i2c->count;
+	if (i2c->state == STATE_READ && i2c->count)
+		meson_i2c_get_data(i2c, i2c->msg->buf + i2c->pos, i2c->count);
 
-		if (i2c->pos >= i2c->msg->len) {
-			i2c->state = STATE_IDLE;
-			complete(&i2c->done);
-			break;
-		}
+	i2c->pos += i2c->count;
 
-		meson_i2c_prepare_xfer(i2c);
-		break;
+	if (i2c->pos >= i2c->msg->len) {
+		i2c->state = STATE_IDLE;
+		complete(&i2c->done);
+		goto out;
 	}
 
+	/* Restart the processing */
+	meson_i2c_prepare_xfer(i2c);
+	meson_i2c_set_mask(i2c, REG_CTRL, REG_CTRL_START, REG_CTRL_START);
 out:
-	if (i2c->state != STATE_IDLE)
-		/* Restart the processing */
-		meson_i2c_set_mask(i2c, REG_CTRL, REG_CTRL_START,
-				   REG_CTRL_START);
-
 	spin_unlock(&i2c->lock);
 
 	return IRQ_HANDLED;
-- 
2.12.0

[PATCH v4 03/10] i2c: meson: set clock divider in probe instead of setting it for each transfer

[Heiner Kallweit]

The bus frequency won't change, therefore we can set the clock divider
in probe already and we don't have to set it for each transfer.

Signed-off-by: Heiner Kallweit <hkallweit1@gmail.com>
---
v2:
- no changes
v3:
- change order of patches
v4:
- no changes
---
 drivers/i2c/busses/i2c-meson.c | 17 ++++++++---------
 1 file changed, 8 insertions(+), 9 deletions(-)

diff --git a/drivers/i2c/busses/i2c-meson.c b/drivers/i2c/busses/i2c-meson.c
index 50059d09..e597764e 100644
--- a/drivers/i2c/busses/i2c-meson.c
+++ b/drivers/i2c/busses/i2c-meson.c
@@ -73,7 +73,6 @@ enum {
  * @error:	Flag set when an error is received
  * @lock:	To avoid race conditions between irq handler and xfer code
  * @done:	Completion used to wait for transfer termination
- * @frequency:	Operating frequency of I2C bus clock
  * @tokens:	Sequence of tokens to be written to the device
  * @num_tokens:	Number of tokens
  */
@@ -92,7 +91,6 @@ struct meson_i2c {
 
 	spinlock_t		lock;
 	struct completion	done;
-	unsigned int		frequency;
 	u32			tokens[2];
 	int			num_tokens;
 };
@@ -131,17 +129,17 @@ static void meson_i2c_write_tokens(struct meson_i2c *i2c)
 	writel(i2c->tokens[1], i2c->regs + REG_TOK_LIST1);
 }
 
-static void meson_i2c_set_clk_div(struct meson_i2c *i2c)
+static void meson_i2c_set_clk_div(struct meson_i2c *i2c, unsigned int freq)
 {
 	unsigned long clk_rate = clk_get_rate(i2c->clk);
 	unsigned int div;
 
-	div = DIV_ROUND_UP(clk_rate, i2c->frequency * 4);
+	div = DIV_ROUND_UP(clk_rate, freq * 4);
 	meson_i2c_set_mask(i2c, REG_CTRL, REG_CTRL_CLKDIV_MASK,
 			   div << REG_CTRL_CLKDIV_SHIFT);
 
 	dev_dbg(i2c->dev, "%s: clk %lu, freq %u, div %u\n", __func__,
-		clk_rate, i2c->frequency, div);
+		clk_rate, freq, div);
 }
 
 static void meson_i2c_get_data(struct meson_i2c *i2c, char *buf, int len)
@@ -361,7 +359,6 @@ static int meson_i2c_xfer(struct i2c_adapter *adap, struct i2c_msg *msgs,
 	int i, ret = 0, count = 0;
 
 	clk_enable(i2c->clk);
-	meson_i2c_set_clk_div(i2c);
 
 	for (i = 0; i < num; i++) {
 		ret = meson_i2c_xfer_msg(i2c, msgs + i, i == num - 1);
@@ -390,15 +387,15 @@ static int meson_i2c_probe(struct platform_device *pdev)
 	struct device_node *np = pdev->dev.of_node;
 	struct meson_i2c *i2c;
 	struct resource *mem;
+	u32 freq;
 	int irq, ret = 0;
 
 	i2c = devm_kzalloc(&pdev->dev, sizeof(struct meson_i2c), GFP_KERNEL);
 	if (!i2c)
 		return -ENOMEM;
 
-	if (of_property_read_u32(pdev->dev.of_node, "clock-frequency",
-				 &i2c->frequency))
-		i2c->frequency = DEFAULT_FREQ;
+	if (of_property_read_u32(pdev->dev.of_node, "clock-frequency", &freq))
+		freq = DEFAULT_FREQ;
 
 	i2c->dev = &pdev->dev;
 	platform_set_drvdata(pdev, i2c);
@@ -456,6 +453,8 @@ static int meson_i2c_probe(struct platform_device *pdev)
 		return ret;
 	}
 
+	meson_i2c_set_clk_div(i2c, freq);
+
 	return 0;
 }
 
-- 
2.12.0

Re: [PATCH v4 03/10] i2c: meson: set clock divider in probe instead of setting it for each transfer

[Wolfram Sang]

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On Tue, Mar 14, 2017 at 10:53:29PM +0100, Heiner Kallweit wrote:
> The bus frequency won't change, therefore we can set the clock divider
> in probe already and we don't have to set it for each transfer.

This is true for some SoCs, but not for all. So, some proof we can
really do it like this would be nice in the commit message, e.g. "parent
clock is fixed anyhow" or something.

> 
> Signed-off-by: Heiner Kallweit <hkallweit1@gmail.com>

[-- Attachment #2: signature.asc --]
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Re: [PATCH v4 03/10] i2c: meson: set clock divider in probe instead of setting it for each transfer

[Heiner Kallweit]

Am 23.03.2017 um 21:31 schrieb Wolfram Sang:
> On Tue, Mar 14, 2017 at 10:53:29PM +0100, Heiner Kallweit wrote:
>> The bus frequency won't change, therefore we can set the clock divider
>> in probe already and we don't have to set it for each transfer.
> 
> This is true for some SoCs, but not for all. So, some proof we can
> really do it like this would be nice in the commit message, e.g. "parent
> clock is fixed anyhow" or something.
> 
Here the bus frequency is fixed to what is set in DT. I'll extend
the commit message.

>>
>> Signed-off-by: Heiner Kallweit <hkallweit1@gmail.com>