[PATCH v4 0/3] Add the clock stretching i2c property

[PATCH v4 0/3] Add the clock stretching i2c property

[Andi Shyti]

Hello,

fter a discussion between Krzysztof and Ryan[1], it has become
apparent that the i2c binding is lacking the definition of a
property that needs to be added at a more generic level. This
property is also used by the mpc i2c controller, which has been
updated in the second patch.

The DTS schema change has been sent as github pull reqest[2][3].

Thanks Krzysztof and Chris for the reviews.

Thank you,
Andi

[1] https://lore.kernel.org/all/c41ee6b5-ddb4-1253-de54-a295b3bab2cc@linaro.org/
[2] https://github.com/devicetree-org/dt-schema/pull/102
[3] https://github.com/devicetree-org/dt-schema/pull/103

Changelog
=========
v3 -> v4:
 - Replaced "i2c-scl-clk-low-timeout-ms" with
   "i2c-scl-clk-low-timeout-us". Use microseconds instead of
   milliseconds.
 - Add tags from Chris.

v2 -> v3:
 - Chris recommended to use of_property_read_u32() instead of
   of_get_property(). Because there were two use of it I added
   the suggested cleanup in a separate patch.

v1 -> v2:
 - Removed the binding patch and send through a different channel
 - To ensure back compatibility, which was broken in v1, the
   legacy "fsl,timeout" has not been removed and marked as
   deprecated. In the driver the that property is checked anyway
   as a fallback in case the main i2c-scl-clk-low-timeout-ms is
   missing.

Andi Shyti (3):
  dt-bindings: i2c: mpc: Mark "fsl,timeout" as deprecated
  i2c: mpc: Use of_property_read_u32 instead of of_get_property
  i2c: mpc: Use i2c-scl-clk-low-timeout-ms i2c property

 .../devicetree/bindings/i2c/i2c-mpc.yaml      |  3 +-
 drivers/i2c/busses/i2c-mpc.c                  | 35 ++++++++++++-------
 2 files changed, 25 insertions(+), 13 deletions(-)

-- 
2.39.2

[PATCH v4 1/3] dt-bindings: i2c: mpc: Mark "fsl,timeout" as deprecated

[Andi Shyti]

Now we have the i2c-scl-clk-low-timeout-us property defined in
the i2c schema.

Mark "fsl,timeout" as deprecated and update the example.

Signed-off-by: Andi Shyti <andi.shyti@kernel.org>
---
 Documentation/devicetree/bindings/i2c/i2c-mpc.yaml | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/Documentation/devicetree/bindings/i2c/i2c-mpc.yaml b/Documentation/devicetree/bindings/i2c/i2c-mpc.yaml
index 018e1b9444248..70fb69b923c46 100644
--- a/Documentation/devicetree/bindings/i2c/i2c-mpc.yaml
+++ b/Documentation/devicetree/bindings/i2c/i2c-mpc.yaml
@@ -43,6 +43,7 @@ properties:
 
   fsl,timeout:
     $ref: /schemas/types.yaml#/definitions/uint32
+    deprecated: true
     description: |
       I2C bus timeout in microseconds
 
@@ -95,6 +96,6 @@ examples:
         interrupts = <43 2>;
         interrupt-parent = <&mpic>;
         clock-frequency = <400000>;
-        fsl,timeout = <10000>;
+        i2c-scl-clk-low-timeout-us = <10000>;
     };
 ...
-- 
2.39.2

Re: [PATCH v4 1/3] dt-bindings: i2c: mpc: Mark "fsl,timeout" as deprecated

[Rob Herring]

On Tue, 14 Mar 2023 22:56:10 +0100, Andi Shyti wrote:
> Now we have the i2c-scl-clk-low-timeout-us property defined in
> the i2c schema.
> 
> Mark "fsl,timeout" as deprecated and update the example.
> 
> Signed-off-by: Andi Shyti <andi.shyti@kernel.org>
> ---
>  Documentation/devicetree/bindings/i2c/i2c-mpc.yaml | 3 ++-
>  1 file changed, 2 insertions(+), 1 deletion(-)
> 

Reviewed-by: Rob Herring <robh@kernel.org>

[PATCH v4 2/3] i2c: mpc: Use of_property_read_u32 instead of of_get_property

[Andi Shyti]

"of_property_read_u32()" is preferred to "of_get_property()" for
retreiving u32 from the device tree. Replace it.

Suggested-by: Chris Packham <chris.packham@alliedtelesis.co.nz>
Signed-off-by: Andi Shyti <andi.shyti@kernel.org>
Tested-by: Chris Packham <chris.packham@alliedtelesis.co.nz>
Reviewed-by: Chris Packham <chris.packham@alliedtelesis.co.nz>
---
 drivers/i2c/busses/i2c-mpc.c | 25 +++++++++++++------------
 1 file changed, 13 insertions(+), 12 deletions(-)

diff --git a/drivers/i2c/busses/i2c-mpc.c b/drivers/i2c/busses/i2c-mpc.c
index 81ac92bb4f6f1..87e5c1725750f 100644
--- a/drivers/i2c/busses/i2c-mpc.c
+++ b/drivers/i2c/busses/i2c-mpc.c
@@ -770,7 +770,6 @@ static const struct i2c_algorithm mpc_algo = {
 static struct i2c_adapter mpc_ops = {
 	.owner = THIS_MODULE,
 	.algo = &mpc_algo,
-	.timeout = HZ,
 };
 
 static struct i2c_bus_recovery_info fsl_i2c_recovery_info = {
@@ -781,11 +780,9 @@ static int fsl_i2c_probe(struct platform_device *op)
 {
 	const struct mpc_i2c_data *data;
 	struct mpc_i2c *i2c;
-	const u32 *prop;
-	u32 clock = MPC_I2C_CLOCK_LEGACY;
-	int result = 0;
-	int plen;
 	struct clk *clk;
+	int result;
+	u32 clock;
 	int err;
 
 	i2c = devm_kzalloc(&op->dev, sizeof(*i2c), GFP_KERNEL);
@@ -831,10 +828,10 @@ static int fsl_i2c_probe(struct platform_device *op)
 	if (of_property_read_bool(op->dev.of_node, "fsl,preserve-clocking")) {
 		clock = MPC_I2C_CLOCK_PRESERVE;
 	} else {
-		prop = of_get_property(op->dev.of_node, "clock-frequency",
-					&plen);
-		if (prop && plen == sizeof(u32))
-			clock = *prop;
+		result = of_property_read_u32(op->dev.of_node,
+					      "clock-frequency", &clock);
+		if (result)
+			clock = MPC_I2C_CLOCK_LEGACY;
 	}
 
 	data = device_get_match_data(&op->dev);
@@ -846,12 +843,16 @@ static int fsl_i2c_probe(struct platform_device *op)
 			mpc_i2c_setup_8xxx(op->dev.of_node, i2c, clock);
 	}
 
-	prop = of_get_property(op->dev.of_node, "fsl,timeout", &plen);
-	if (prop && plen == sizeof(u32)) {
-		mpc_ops.timeout = *prop * HZ / 1000000;
+	result = of_property_read_u32(op->dev.of_node,
+				      "fsl,timeout", &mpc_ops.timeout);
+	if (!result) {
+		mpc_ops.timeout *= HZ / 1000000;
 		if (mpc_ops.timeout < 5)
 			mpc_ops.timeout = 5;
+	} else {
+		mpc_ops.timeout = HZ;
 	}
+
 	dev_info(i2c->dev, "timeout %u us\n", mpc_ops.timeout * 1000000 / HZ);
 
 	if (of_property_read_bool(op->dev.of_node, "fsl,i2c-erratum-a004447"))
-- 
2.39.2

[PATCH v4 3/3] i2c: mpc: Use i2c-scl-clk-low-timeout-ms i2c property

[Andi Shyti]

"fsl,timeout" is marked as deprecated and replaced by the
"i2c-scl-clk-low-timeout-us" i2c property.

Use this latter and, in case it is missing, for back
compatibility, check whether we still have "fsl,timeout" defined.

Signed-off-by: Andi Shyti <andi.shyti@kernel.org>
Reviewed-by: Chris Packham <chris.packham@alliedtelesis.co.nz>
Tested-by: Chris Packham <chris.packham@alliedtelesis.co.nz>
---
 drivers/i2c/busses/i2c-mpc.c | 12 +++++++++++-
 1 file changed, 11 insertions(+), 1 deletion(-)

diff --git a/drivers/i2c/busses/i2c-mpc.c b/drivers/i2c/busses/i2c-mpc.c
index 87e5c1725750f..e8798f9c23fcc 100644
--- a/drivers/i2c/busses/i2c-mpc.c
+++ b/drivers/i2c/busses/i2c-mpc.c
@@ -843,8 +843,18 @@ static int fsl_i2c_probe(struct platform_device *op)
 			mpc_i2c_setup_8xxx(op->dev.of_node, i2c, clock);
 	}
 
+	/*
+	 * "fsl,timeout" has been marked as deprecated and, to maintain
+	 * backward compatibility, we will only look for it if
+	 * "i2c-scl-clk-low-timeout-ms" is not present.
+	 */
 	result = of_property_read_u32(op->dev.of_node,
-				      "fsl,timeout", &mpc_ops.timeout);
+				      "i2c-scl-clk-low-timeout-us",
+				      &mpc_ops.timeout);
+	if (result == -EINVAL)
+		result = of_property_read_u32(op->dev.of_node,
+					      "fsl,timeout", &mpc_ops.timeout);
+
 	if (!result) {
 		mpc_ops.timeout *= HZ / 1000000;
 		if (mpc_ops.timeout < 5)
-- 
2.39.2

Re: [PATCH v4 3/3] i2c: mpc: Use i2c-scl-clk-low-timeout-ms i2c property

[Chris Packham]

Just to be a pain the subject line still says "ms"

On 15/03/23 10:56, Andi Shyti wrote:
> "fsl,timeout" is marked as deprecated and replaced by the
> "i2c-scl-clk-low-timeout-us" i2c property.
>
> Use this latter and, in case it is missing, for back
> compatibility, check whether we still have "fsl,timeout" defined.
>
> Signed-off-by: Andi Shyti <andi.shyti@kernel.org>
> Reviewed-by: Chris Packham <chris.packham@alliedtelesis.co.nz>
> Tested-by: Chris Packham <chris.packham@alliedtelesis.co.nz>
> ---
>   drivers/i2c/busses/i2c-mpc.c | 12 +++++++++++-
>   1 file changed, 11 insertions(+), 1 deletion(-)
>
> diff --git a/drivers/i2c/busses/i2c-mpc.c b/drivers/i2c/busses/i2c-mpc.c
> index 87e5c1725750f..e8798f9c23fcc 100644
> --- a/drivers/i2c/busses/i2c-mpc.c
> +++ b/drivers/i2c/busses/i2c-mpc.c
> @@ -843,8 +843,18 @@ static int fsl_i2c_probe(struct platform_device *op)
>   			mpc_i2c_setup_8xxx(op->dev.of_node, i2c, clock);
>   	}
>   
> +	/*
> +	 * "fsl,timeout" has been marked as deprecated and, to maintain
> +	 * backward compatibility, we will only look for it if
> +	 * "i2c-scl-clk-low-timeout-ms" is not present.
> +	 */
>   	result = of_property_read_u32(op->dev.of_node,
> -				      "fsl,timeout", &mpc_ops.timeout);
> +				      "i2c-scl-clk-low-timeout-us",
> +				      &mpc_ops.timeout);
> +	if (result == -EINVAL)
> +		result = of_property_read_u32(op->dev.of_node,
> +					      "fsl,timeout", &mpc_ops.timeout);
> +
>   	if (!result) {
>   		mpc_ops.timeout *= HZ / 1000000;
>   		if (mpc_ops.timeout < 5)

Re: [PATCH v4 3/3] i2c: mpc: Use i2c-scl-clk-low-timeout-ms i2c property

[Andi Shyti]

> Just to be a pain the subject line still says "ms"

I have changed hundreds of /ms/us/ in this last half an hour...
of course I forgot some :)

There is also one in the comment.

Thanks for spotting it, Chris!

Andi

> On 15/03/23 10:56, Andi Shyti wrote:
> > "fsl,timeout" is marked as deprecated and replaced by the
> > "i2c-scl-clk-low-timeout-us" i2c property.
> >
> > Use this latter and, in case it is missing, for back
> > compatibility, check whether we still have "fsl,timeout" defined.
> >
> > Signed-off-by: Andi Shyti <andi.shyti@kernel.org>
> > Reviewed-by: Chris Packham <chris.packham@alliedtelesis.co.nz>
> > Tested-by: Chris Packham <chris.packham@alliedtelesis.co.nz>
> > ---
> >   drivers/i2c/busses/i2c-mpc.c | 12 +++++++++++-
> >   1 file changed, 11 insertions(+), 1 deletion(-)
> >
> > diff --git a/drivers/i2c/busses/i2c-mpc.c b/drivers/i2c/busses/i2c-mpc.c
> > index 87e5c1725750f..e8798f9c23fcc 100644
> > --- a/drivers/i2c/busses/i2c-mpc.c
> > +++ b/drivers/i2c/busses/i2c-mpc.c
> > @@ -843,8 +843,18 @@ static int fsl_i2c_probe(struct platform_device *op)
> >   			mpc_i2c_setup_8xxx(op->dev.of_node, i2c, clock);
> >   	}
> >   
> > +	/*
> > +	 * "fsl,timeout" has been marked as deprecated and, to maintain
> > +	 * backward compatibility, we will only look for it if
> > +	 * "i2c-scl-clk-low-timeout-ms" is not present.
> > +	 */
> >   	result = of_property_read_u32(op->dev.of_node,
> > -				      "fsl,timeout", &mpc_ops.timeout);
> > +				      "i2c-scl-clk-low-timeout-us",
> > +				      &mpc_ops.timeout);
> > +	if (result == -EINVAL)
> > +		result = of_property_read_u32(op->dev.of_node,
> > +					      "fsl,timeout", &mpc_ops.timeout);
> > +
> >   	if (!result) {
> >   		mpc_ops.timeout *= HZ / 1000000;
> >   		if (mpc_ops.timeout < 5)

[PATCH v5 3/3] i2c: mpc: Use i2c-scl-clk-low-timeout-us i2c property

[Andi Shyti]

"fsl,timeout" is marked as deprecated and replaced by the
"i2c-scl-clk-low-timeout-us" i2c property.

Use this latter and, in case it is missing, for back
compatibility, check whether we still have "fsl,timeout" defined.

Signed-off-by: Andi Shyti <andi.shyti@kernel.org>
Reviewed-by: Chris Packham <chris.packham@alliedtelesis.co.nz>
Tested-by: Chris Packham <chris.packham@alliedtelesis.co.nz>
---
Hi,

this should be the only patch where I forgot an 'ms'.
It should be fixed now.

Thanks, Chris.

V4 -> v5
 - replace /ms/us/ in the commit subject and in the comment.

 drivers/i2c/busses/i2c-mpc.c | 12 +++++++++++-
 1 file changed, 11 insertions(+), 1 deletion(-)

diff --git a/drivers/i2c/busses/i2c-mpc.c b/drivers/i2c/busses/i2c-mpc.c
index 87e5c1725750f..aec3ac387c579 100644
--- a/drivers/i2c/busses/i2c-mpc.c
+++ b/drivers/i2c/busses/i2c-mpc.c
@@ -843,8 +843,18 @@ static int fsl_i2c_probe(struct platform_device *op)
 			mpc_i2c_setup_8xxx(op->dev.of_node, i2c, clock);
 	}
 
+	/*
+	 * "fsl,timeout" has been marked as deprecated and, to maintain
+	 * backward compatibility, we will only look for it if
+	 * "i2c-scl-clk-low-timeout-us" is not present.
+	 */
 	result = of_property_read_u32(op->dev.of_node,
-				      "fsl,timeout", &mpc_ops.timeout);
+				      "i2c-scl-clk-low-timeout-us",
+				      &mpc_ops.timeout);
+	if (result == -EINVAL)
+		result = of_property_read_u32(op->dev.of_node,
+					      "fsl,timeout", &mpc_ops.timeout);
+
 	if (!result) {
 		mpc_ops.timeout *= HZ / 1000000;
 		if (mpc_ops.timeout < 5)
-- 
2.39.2

Re: [PATCH v5 3/3] i2c: mpc: Use i2c-scl-clk-low-timeout-us i2c property

[Krzysztof Kozlowski]

On 14/03/2023 23:16, Andi Shyti wrote:
> "fsl,timeout" is marked as deprecated and replaced by the
> "i2c-scl-clk-low-timeout-us" i2c property.
> 
> Use this latter and, in case it is missing, for back
> compatibility, check whether we still have "fsl,timeout" defined.
> 
> Signed-off-by: Andi Shyti <andi.shyti@kernel.org>
> Reviewed-by: Chris Packham <chris.packham@alliedtelesis.co.nz>
> Tested-by: Chris Packham <chris.packham@alliedtelesis.co.nz>
> ---
> Hi,
> 
> this should be the only patch where I forgot an 'ms'.
> It should be fixed now.
> 
> Thanks, Chris.
> 
> V4 -> v5
>  - replace /ms/us/ in the commit subject and in the comment.
> 

Please send entire new v5, because this messes with our
threading/reviewing and our tools.


Reviewed-by: Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org>

Best regards,
Krzysztof

Re: [PATCH v5 3/3] i2c: mpc: Use i2c-scl-clk-low-timeout-us i2c property

[Andi Shyti]

Hi Krzysztof,

On Fri, Mar 17, 2023 at 10:26:21AM +0100, Krzysztof Kozlowski wrote:
> On 14/03/2023 23:16, Andi Shyti wrote:
> > "fsl,timeout" is marked as deprecated and replaced by the
> > "i2c-scl-clk-low-timeout-us" i2c property.
> > 
> > Use this latter and, in case it is missing, for back
> > compatibility, check whether we still have "fsl,timeout" defined.
> > 
> > Signed-off-by: Andi Shyti <andi.shyti@kernel.org>
> > Reviewed-by: Chris Packham <chris.packham@alliedtelesis.co.nz>
> > Tested-by: Chris Packham <chris.packham@alliedtelesis.co.nz>
> > ---
> > Hi,
> > 
> > this should be the only patch where I forgot an 'ms'.
> > It should be fixed now.
> > 
> > Thanks, Chris.
> > 
> > V4 -> v5
> >  - replace /ms/us/ in the commit subject and in the comment.
> > 
> 
> Please send entire new v5, because this messes with our
> threading/reviewing and our tools.

ah... tools!

Sure... will do!

> Reviewed-by: Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org>

Thanks!

Andi

Re: [PATCH v4 3/3] i2c: mpc: Use i2c-scl-clk-low-timeout-ms i2c property

[Krzysztof Kozlowski]

On 14/03/2023 22:56, Andi Shyti wrote:
> "fsl,timeout" is marked as deprecated and replaced by the
> "i2c-scl-clk-low-timeout-us" i2c property.
> 
> Use this latter and, in case it is missing, for back
> compatibility, check whether we still have "fsl,timeout" defined.
> 
> Signed-off-by: Andi Shyti <andi.shyti@kernel.org>
> Reviewed-by: Chris Packham <chris.packham@alliedtelesis.co.nz>
> Tested-by: Chris Packham <chris.packham@alliedtelesis.co.nz>
> ---


Reviewed-by: Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org>

Best regards,
Krzysztof