[PATCH v2 0/2] Add the clock stretching i2c property

[PATCH v2 0/2] 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].

Thanks Krzysztof for the review.

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

Changelog
=========
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 (2):
  dt-bindings: i2c: mpc: Mark "fsl,timeout" as deprecated
  i2c: mpc: Use i2c-scl-clk-low-timeout-ms i2c property

 Documentation/devicetree/bindings/i2c/i2c-mpc.yaml |  3 ++-
 drivers/i2c/busses/i2c-mpc.c                       | 11 ++++++++++-
 2 files changed, 12 insertions(+), 2 deletions(-)

-- 
2.39.2

[PATCH v2 1/2] dt-bindings: i2c: mpc: Mark "fsl,timeout" as deprecated

[Andi Shyti]

Now we have the i2c-scl-clk-low-timeout-ms 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 018e1b944424..bd2dd82471c1 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-ms = <10000>;
     };
 ...
-- 
2.39.2

[PATCH v2 2/2] 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-ms" 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>
---
 drivers/i2c/busses/i2c-mpc.c | 11 ++++++++++-
 1 file changed, 10 insertions(+), 1 deletion(-)

diff --git a/drivers/i2c/busses/i2c-mpc.c b/drivers/i2c/busses/i2c-mpc.c
index 81ac92bb4f6f..fe6279a353c6 100644
--- a/drivers/i2c/busses/i2c-mpc.c
+++ b/drivers/i2c/busses/i2c-mpc.c
@@ -846,7 +846,16 @@ 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);
+	prop = of_get_property(op->dev.of_node,
+			       "i2c-scl-clk-low-timeout-ms", &plen);
+
+	/*
+	 * ensuring back compatibility as
+	 * "fsl,timeout" is marked as deprecated
+	 */
+	if (!prop)
+		prop = of_get_property(op->dev.of_node, "fsl,timeout", &plen);
+
 	if (prop && plen == sizeof(u32)) {
 		mpc_ops.timeout = *prop * HZ / 1000000;
 		if (mpc_ops.timeout < 5)
-- 
2.39.2

Re: [PATCH v2 2/2] i2c: mpc: Use i2c-scl-clk-low-timeout-ms i2c property

[Chris Packham]

On 13/03/23 03:55, Andi Shyti wrote:
> "fsl,timeout" is marked as deprecated and replaced by the
> "i2c-scl-clk-low-timeout-ms" 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>
> ---
>   drivers/i2c/busses/i2c-mpc.c | 11 ++++++++++-
>   1 file changed, 10 insertions(+), 1 deletion(-)
>
> diff --git a/drivers/i2c/busses/i2c-mpc.c b/drivers/i2c/busses/i2c-mpc.c
> index 81ac92bb4f6f..fe6279a353c6 100644
> --- a/drivers/i2c/busses/i2c-mpc.c
> +++ b/drivers/i2c/busses/i2c-mpc.c
> @@ -846,7 +846,16 @@ 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);
> +	prop = of_get_property(op->dev.of_node,
> +			       "i2c-scl-clk-low-timeout-ms", &plen);
> +
> +	/*
> +	 * ensuring back compatibility as
> +	 * "fsl,timeout" is marked as deprecated
> +	 */
> +	if (!prop)
> +		prop = of_get_property(op->dev.of_node, "fsl,timeout", &plen);
> +
>   	if (prop && plen == sizeof(u32)) {
>   		mpc_ops.timeout = *prop * HZ / 1000000;
>   		if (mpc_ops.timeout < 5)

While you're here it might make sense to clean this up to use 
of_property_read_u32().

With or without that additional cleanup:

Reviewed-by: Chris Packham <chris.packham@alliedtelesis.co.nz>