[PATCH 0/3] pwm: pxa: Use #pwm-cells = <3>

[PATCH 0/3] pwm: pxa: Use #pwm-cells = <3>

[Uwe Kleine-König]

Hello,

this series' goal is to soften the special device-tree binding of
marvel,pxa-pwm devices. This is the only binding that doesn't pass the
line index as first parameter. 

Here the #pwm-cells value is bumped from 1 to 3, keeping compatibility
with the old binding. 

The motivation for this was that Hervé sent a patch introducing pwm
nexus nodes which don't work nicely with the marvel,pxa-pwm
particularities.

For merging this series (assuming device-tree and pxa maintainers agree)
I guess keeping the patches together makes sense because with the 2nd
patch applied but without the 3rd there are a few dt-checker warnings.

So I suggest to take it via my pwm tree as I guess drivers/pwm/core.c
has more potential for a conflict than arch/arm/boot/dts/intel/pxa.
So please send Acks and tell me if you would need an immutable branch
for pulling into the PXA tree.

Best regards
Uwe

Uwe Kleine-König (3):
  pwm: Add upgrade path to #pwm-cells = <3> for users of
    of_pwm_single_xlate()
  dt-bindings: pwm: marvell,pxa-pwm: Update to use #pwm-cells = <3>
  ARM: dts: pxa: Use #pwm-cells = <3> for marvell,pxa-pwm devices

 .../devicetree/bindings/pwm/marvell,pxa-pwm.yaml |  3 +--
 arch/arm/boot/dts/intel/pxa/pxa25x.dtsi          |  4 ++--
 arch/arm/boot/dts/intel/pxa/pxa27x.dtsi          |  8 ++++----
 .../dts/intel/pxa/pxa300-raumfeld-controller.dts |  2 +-
 arch/arm/boot/dts/intel/pxa/pxa3xx.dtsi          |  8 ++++----
 drivers/pwm/core.c                               | 16 ++++++++++++++++
 6 files changed, 28 insertions(+), 13 deletions(-)


base-commit: c98e66144b7d07ee9a3ca8241123b628a8ac0288
-- 
2.47.1

[PATCH 1/3] pwm: Add upgrade path to #pwm-cells = <3> for users of of_pwm_single_xlate()

[Uwe Kleine-König]

The PWM chip on PXA only has a single output. Back when the device tree
binding was defined it was considered a good idea to not pass the PWM
line index as is done for all other PWM types as it would be always zero
anyhow and so doesn't add any value.

However for consistency reasons it is nice when all PWMs use the same
binding. For that reason let of_pwm_single_xlate() (i.e. the function
that implements the PXA behaviour) behave in the same way as
of_pwm_xlate_with_flags() for 3 (or more) parameters. With that in
place, the pxa-pwm binding can be updated to #pwm-cells = <3> without
breaking old device trees that stick to #pwm-cells = <1>.

Signed-off-by: Uwe Kleine-König <u.kleine-koenig@baylibre.com>
---
 drivers/pwm/core.c | 16 ++++++++++++++++
 1 file changed, 16 insertions(+)

diff --git a/drivers/pwm/core.c b/drivers/pwm/core.c
index ccd54c089bab..bc05818fa370 100644
--- a/drivers/pwm/core.c
+++ b/drivers/pwm/core.c
@@ -1000,11 +1000,27 @@ of_pwm_xlate_with_flags(struct pwm_chip *chip, const struct of_phandle_args *arg
 }
 EXPORT_SYMBOL_GPL(of_pwm_xlate_with_flags);
 
+/*
+ * This callback is used for PXA PWM chips that only have a single PWM line.
+ * For such chips you could argue that passing the line number (i.e. the first
+ * parameter in the common case) is useless as it's always zero. So compared to
+ * the default xlate function of_pwm_xlate_with_flags() the first parameter is
+ * the default period and the second are flags.
+ *
+ * Note that if #pwm-cells = <3>, the semantic is the same as for
+ * of_pwm_xlate_with_flags() to allow converting the affected driver to
+ * #pwm-cells = <3> without breaking the legacy binding.
+ *
+ * Don't use for new drivers.
+ */
 struct pwm_device *
 of_pwm_single_xlate(struct pwm_chip *chip, const struct of_phandle_args *args)
 {
 	struct pwm_device *pwm;
 
+	if (args->args_count >= 3)
+		return of_pwm_xlate_with_flags(chip, args);
+
 	pwm = pwm_request_from_chip(chip, 0, NULL);
 	if (IS_ERR(pwm))
 		return pwm;
-- 
2.47.1

[PATCH 2/3] dt-bindings: pwm: marvell,pxa-pwm: Update to use #pwm-cells = <3>

[Uwe Kleine-König]

The PXA PWM binding is the only one that doesn't pass the PWM line index
as first parameter of the parameter cells. However this can be upgraded
to the mandatory binding for all new PWM drivers without breaking
compatibility for old device trees using #pwm-cells = <1>.

So bump #pwm-cells to 3 with the (undocumented) promise to keep the old
behaviour for #pwm-cells = <1>.

Signed-off-by: Uwe Kleine-König <u.kleine-koenig@baylibre.com>
---
 Documentation/devicetree/bindings/pwm/marvell,pxa-pwm.yaml | 3 +--
 1 file changed, 1 insertion(+), 2 deletions(-)

diff --git a/Documentation/devicetree/bindings/pwm/marvell,pxa-pwm.yaml b/Documentation/devicetree/bindings/pwm/marvell,pxa-pwm.yaml
index 9ee1946dc2e1..ba7fba67e19e 100644
--- a/Documentation/devicetree/bindings/pwm/marvell,pxa-pwm.yaml
+++ b/Documentation/devicetree/bindings/pwm/marvell,pxa-pwm.yaml
@@ -25,8 +25,7 @@ properties:
     maxItems: 1
 
   "#pwm-cells":
-    # Used for specifying the period length in nanoseconds
-    const: 1
+    const: 3
 
   clocks:
     maxItems: 1
-- 
2.47.1

[PATCH 3/3] ARM: dts: pxa: Use #pwm-cells = <3> for marvell,pxa-pwm devices

[Uwe Kleine-König]

For consistency with most other pwm bindings, also use 3 cells for
phandles to PWM devices.

Signed-off-by: Uwe Kleine-König <u.kleine-koenig@baylibre.com>
---
 arch/arm/boot/dts/intel/pxa/pxa25x.dtsi                   | 4 ++--
 arch/arm/boot/dts/intel/pxa/pxa27x.dtsi                   | 8 ++++----
 .../arm/boot/dts/intel/pxa/pxa300-raumfeld-controller.dts | 2 +-
 arch/arm/boot/dts/intel/pxa/pxa3xx.dtsi                   | 8 ++++----
 4 files changed, 11 insertions(+), 11 deletions(-)

diff --git a/arch/arm/boot/dts/intel/pxa/pxa25x.dtsi b/arch/arm/boot/dts/intel/pxa/pxa25x.dtsi
index 5f8300e356ad..d25065caeebc 100644
--- a/arch/arm/boot/dts/intel/pxa/pxa25x.dtsi
+++ b/arch/arm/boot/dts/intel/pxa/pxa25x.dtsi
@@ -67,14 +67,14 @@ gpio: gpio@40e00000 {
 		pwm0: pwm@40b00000 {
 			compatible = "marvell,pxa250-pwm";
 			reg = <0x40b00000 0x10>;
-			#pwm-cells = <1>;
+			#pwm-cells = <3>;
 			clocks = <&clks CLK_PWM0>;
 		};
 
 		pwm1: pwm@40b00010 {
 			compatible = "marvell,pxa250-pwm";
 			reg = <0x40b00010 0x10>;
-			#pwm-cells = <1>;
+			#pwm-cells = <3>;
 			clocks = <&clks CLK_PWM1>;
 		};
 
diff --git a/arch/arm/boot/dts/intel/pxa/pxa27x.dtsi b/arch/arm/boot/dts/intel/pxa/pxa27x.dtsi
index a2cbfb3be609..ed07b65cc362 100644
--- a/arch/arm/boot/dts/intel/pxa/pxa27x.dtsi
+++ b/arch/arm/boot/dts/intel/pxa/pxa27x.dtsi
@@ -49,28 +49,28 @@ usb0: usb@4c000000 {
 		pwm0: pwm@40b00000 {
 			compatible = "marvell,pxa270-pwm", "marvell,pxa250-pwm";
 			reg = <0x40b00000 0x10>;
-			#pwm-cells = <1>;
+			#pwm-cells = <3>;
 			clocks = <&clks CLK_PWM0>;
 		};
 
 		pwm1: pwm@40b00010 {
 			compatible = "marvell,pxa270-pwm", "marvell,pxa250-pwm";
 			reg = <0x40b00010 0x10>;
-			#pwm-cells = <1>;
+			#pwm-cells = <3>;
 			clocks = <&clks CLK_PWM1>;
 		};
 
 		pwm2: pwm@40c00000 {
 			compatible = "marvell,pxa270-pwm", "marvell,pxa250-pwm";
 			reg = <0x40c00000 0x10>;
-			#pwm-cells = <1>;
+			#pwm-cells = <3>;
 			clocks = <&clks CLK_PWM0>;
 		};
 
 		pwm3: pwm@40c00010 {
 			compatible = "marvell,pxa270-pwm", "marvell,pxa250-pwm";
 			reg = <0x40c00010 0x10>;
-			#pwm-cells = <1>;
+			#pwm-cells = <3>;
 			clocks = <&clks CLK_PWM1>;
 		};
 
diff --git a/arch/arm/boot/dts/intel/pxa/pxa300-raumfeld-controller.dts b/arch/arm/boot/dts/intel/pxa/pxa300-raumfeld-controller.dts
index 12b15945ac6d..9094ec422577 100644
--- a/arch/arm/boot/dts/intel/pxa/pxa300-raumfeld-controller.dts
+++ b/arch/arm/boot/dts/intel/pxa/pxa300-raumfeld-controller.dts
@@ -56,7 +56,7 @@ backlight-controller-pwm {
 		compatible = "pwm-backlight";
 		pinctrl-names = "default";
 		pinctrl-0 = <&pwm0_pins>;
-		pwms = <&pwm0 10000>;
+		pwms = <&pwm0 0 10000 0>;
 		power-supply = <&reg_vbatt>;
 		status = "disabled";
 
diff --git a/arch/arm/boot/dts/intel/pxa/pxa3xx.dtsi b/arch/arm/boot/dts/intel/pxa/pxa3xx.dtsi
index f9c216f91865..4e69b4da0ba6 100644
--- a/arch/arm/boot/dts/intel/pxa/pxa3xx.dtsi
+++ b/arch/arm/boot/dts/intel/pxa/pxa3xx.dtsi
@@ -224,7 +224,7 @@ usb0: usb@4c000000 {
 		pwm0: pwm@40b00000 {
 			compatible = "marvell,pxa270-pwm";
 			reg = <0x40b00000 0x10>;
-			#pwm-cells = <1>;
+			#pwm-cells = <3>;
 			clocks = <&clks CLK_PWM0>;
 			status = "disabled";
 		};
@@ -232,7 +232,7 @@ pwm0: pwm@40b00000 {
 		pwm1: pwm@40b00010 {
 			compatible = "marvell,pxa270-pwm";
 			reg = <0x40b00010 0x10>;
-			#pwm-cells = <1>;
+			#pwm-cells = <3>;
 			clocks = <&clks CLK_PWM1>;
 			status = "disabled";
 		};
@@ -240,7 +240,7 @@ pwm1: pwm@40b00010 {
 		pwm2: pwm@40c00000 {
 			compatible = "marvell,pxa270-pwm";
 			reg = <0x40c00000 0x10>;
-			#pwm-cells = <1>;
+			#pwm-cells = <3>;
 			clocks = <&clks CLK_PWM0>;
 			status = "disabled";
 		};
@@ -248,7 +248,7 @@ pwm2: pwm@40c00000 {
 		pwm3: pwm@40c00010 {
 			compatible = "marvell,pxa270-pwm";
 			reg = <0x40c00010 0x10>;
-			#pwm-cells = <1>;
+			#pwm-cells = <3>;
 			clocks = <&clks CLK_PWM1>;
 			status = "disabled";
 		};
-- 
2.47.1

Re: [PATCH 1/3] pwm: Add upgrade path to #pwm-cells = <3> for users of of_pwm_single_xlate()

[Herve Codina]

On Wed,  5 Feb 2025 18:54:00 +0100
Uwe Kleine-König <u.kleine-koenig@baylibre.com> wrote:

> The PWM chip on PXA only has a single output. Back when the device tree
> binding was defined it was considered a good idea to not pass the PWM
> line index as is done for all other PWM types as it would be always zero
> anyhow and so doesn't add any value.
> 
> However for consistency reasons it is nice when all PWMs use the same
> binding. For that reason let of_pwm_single_xlate() (i.e. the function
> that implements the PXA behaviour) behave in the same way as
> of_pwm_xlate_with_flags() for 3 (or more) parameters. With that in
> place, the pxa-pwm binding can be updated to #pwm-cells = <3> without
> breaking old device trees that stick to #pwm-cells = <1>.
> 
> Signed-off-by: Uwe Kleine-König <u.kleine-koenig@baylibre.com>
> ---
>  drivers/pwm/core.c | 16 ++++++++++++++++
>  1 file changed, 16 insertions(+)

Reviewed-by: Herve Codina <herve.codina@bootlin.com>

Best regards,
Hervé

Re: [PATCH 0/3] pwm: pxa: Use #pwm-cells = <3>

[Daniel Mack]

On 05.02.25 18:53, Uwe Kleine-König wrote:
> Hello,
> 
> this series' goal is to soften the special device-tree binding of
> marvel,pxa-pwm devices. This is the only binding that doesn't pass the
> line index as first parameter.
> 
> Here the #pwm-cells value is bumped from 1 to 3, keeping compatibility
> with the old binding.
> 
> The motivation for this was that Hervé sent a patch introducing pwm
> nexus nodes which don't work nicely with the marvel,pxa-pwm
> particularities.
> 
> For merging this series (assuming device-tree and pxa maintainers agree)
> I guess keeping the patches together makes sense because with the 2nd
> patch applied but without the 3rd there are a few dt-checker warnings.
> 
> So I suggest to take it via my pwm tree as I guess drivers/pwm/core.c
> has more potential for a conflict than arch/arm/boot/dts/intel/pxa.
> So please send Acks and tell me if you would need an immutable branch
> for pulling into the PXA tree.
> 
> Best regards
> Uwe
> 
> Uwe Kleine-König (3):
>    pwm: Add upgrade path to #pwm-cells = <3> for users of
>      of_pwm_single_xlate()
>    dt-bindings: pwm: marvell,pxa-pwm: Update to use #pwm-cells = <3>
>    ARM: dts: pxa: Use #pwm-cells = <3> for marvell,pxa-pwm devices

For all patches in the series:

Reviewed-by: Daniel Mack <daniel@zonque.org>

> 
>   .../devicetree/bindings/pwm/marvell,pxa-pwm.yaml |  3 +--
>   arch/arm/boot/dts/intel/pxa/pxa25x.dtsi          |  4 ++--
>   arch/arm/boot/dts/intel/pxa/pxa27x.dtsi          |  8 ++++----
>   .../dts/intel/pxa/pxa300-raumfeld-controller.dts |  2 +-
>   arch/arm/boot/dts/intel/pxa/pxa3xx.dtsi          |  8 ++++----
>   drivers/pwm/core.c                               | 16 ++++++++++++++++
>   6 files changed, 28 insertions(+), 13 deletions(-)
> 
> 
> base-commit: c98e66144b7d07ee9a3ca8241123b628a8ac0288

Re: [PATCH 2/3] dt-bindings: pwm: marvell,pxa-pwm: Update to use #pwm-cells = <3>

[Conor Dooley]

[-- Attachment #1: Type: text/plain, Size: 588 bytes --]

On Wed, Feb 05, 2025 at 06:54:01PM +0100, Uwe Kleine-König wrote:
> The PXA PWM binding is the only one that doesn't pass the PWM line index
> as first parameter of the parameter cells. However this can be upgraded
> to the mandatory binding for all new PWM drivers without breaking
> compatibility for old device trees using #pwm-cells = <1>.
> 
> So bump #pwm-cells to 3 with the (undocumented) promise to keep the old
> behaviour for #pwm-cells = <1>.
> 
> Signed-off-by: Uwe Kleine-König <u.kleine-koenig@baylibre.com>

Acked-by: Conor Dooley <conor.dooley@microchip.com>

[-- Attachment #2: signature.asc --]
[-- Type: application/pgp-signature, Size: 228 bytes --]

Re: [PATCH 2/3] dt-bindings: pwm: marvell,pxa-pwm: Update to use #pwm-cells = <3>

[Rob Herring (Arm)]

On Wed, 05 Feb 2025 18:54:01 +0100, Uwe Kleine-König wrote:
> The PXA PWM binding is the only one that doesn't pass the PWM line index
> as first parameter of the parameter cells. However this can be upgraded
> to the mandatory binding for all new PWM drivers without breaking
> compatibility for old device trees using #pwm-cells = <1>.
> 
> So bump #pwm-cells to 3 with the (undocumented) promise to keep the old
> behaviour for #pwm-cells = <1>.
> 
> Signed-off-by: Uwe Kleine-König <u.kleine-koenig@baylibre.com>
> ---
>  Documentation/devicetree/bindings/pwm/marvell,pxa-pwm.yaml | 3 +--
>  1 file changed, 1 insertion(+), 2 deletions(-)
> 

My bot found errors running 'make dt_binding_check' on your patch:

yamllint warnings/errors:

dtschema/dtc warnings/errors:
/builds/robherring/dt-review-ci/linux/Documentation/devicetree/bindings/pwm/marvell,pxa-pwm.example.dtb: pwm@40b00000: #pwm-cells: 3 was expected
	from schema $id: http://devicetree.org/schemas/pwm/marvell,pxa-pwm.yaml#

doc reference errors (make refcheckdocs):

See https://patchwork.ozlabs.org/project/devicetree-bindings/patch/266765abb8251bd60796a3c4270e3809bfff952e.1738777221.git.u.kleine-koenig@baylibre.com

The base for the series is generally the latest rc1. A different dependency
should be noted in *this* patch.

If you already ran 'make dt_binding_check' and didn't see the above
error(s), then make sure 'yamllint' is installed and dt-schema is up to
date:

pip3 install dtschema --upgrade

Please check and re-submit after running the above command yourself. Note
that DT_SCHEMA_FILES can be set to your schema file to speed up checking
your schema. However, it must be unset to test all examples with your schema.