[PATCH 1/5] pwm: mediatek: add a property "mediatek,num-pwms"

[PATCH 1/5] pwm: mediatek: add a property "mediatek,num-pwms"

[Ryder Lee]

This adds a property "mediatek,num-pwms" to avoid having an endless
list of compatibles with no other differences for the same driver.

Signed-off-by: Ryder Lee <ryder.lee@mediatek.com>
---
 drivers/pwm/pwm-mediatek.c | 25 +++++++++++--------------
 1 file changed, 11 insertions(+), 14 deletions(-)

diff --git a/drivers/pwm/pwm-mediatek.c b/drivers/pwm/pwm-mediatek.c
index eb6674c..37daa84 100644
--- a/drivers/pwm/pwm-mediatek.c
+++ b/drivers/pwm/pwm-mediatek.c
@@ -55,7 +55,6 @@ enum {
 };
 
 struct mtk_pwm_platform_data {
-	unsigned int num_pwms;
 	bool pwm45_fixup;
 	bool has_clks;
 };
@@ -226,10 +225,11 @@ static void mtk_pwm_disable(struct pwm_chip *chip, struct pwm_device *pwm)
 
 static int mtk_pwm_probe(struct platform_device *pdev)
 {
+	struct device_node *np = pdev->dev.of_node;
 	const struct mtk_pwm_platform_data *data;
 	struct mtk_pwm_chip *pc;
 	struct resource *res;
-	unsigned int i;
+	unsigned int i, num_pwms;
 	int ret;
 
 	pc = devm_kzalloc(&pdev->dev, sizeof(*pc), GFP_KERNEL);
@@ -246,7 +246,13 @@ static int mtk_pwm_probe(struct platform_device *pdev)
 	if (IS_ERR(pc->regs))
 		return PTR_ERR(pc->regs);
 
-	for (i = 0; i < data->num_pwms + 2 && pc->soc->has_clks; i++) {
+	ret = of_property_read_u32(np, "mediatek,num-pwms", &num_pwms);
+	if (ret < 0) {
+		dev_err(&pdev->dev, "failed to get pwm number: %d\n", ret);
+		return ret;
+	}
+
+	for (i = 0; i < num_pwms + 2 && pc->soc->has_clks; i++) {
 		pc->clks[i] = devm_clk_get(&pdev->dev, mtk_pwm_clk_name[i]);
 		if (IS_ERR(pc->clks[i])) {
 			dev_err(&pdev->dev, "clock: %s fail: %ld\n",
@@ -260,7 +266,7 @@ static int mtk_pwm_probe(struct platform_device *pdev)
 	pc->chip.dev = &pdev->dev;
 	pc->chip.ops = &mtk_pwm_ops;
 	pc->chip.base = -1;
-	pc->chip.npwm = data->num_pwms;
+	pc->chip.npwm = num_pwms;
 
 	ret = pwmchip_add(&pc->chip);
 	if (ret < 0) {
@@ -279,32 +285,23 @@ static int mtk_pwm_remove(struct platform_device *pdev)
 }
 
 static const struct mtk_pwm_platform_data mt2712_pwm_data = {
-	.num_pwms = 8,
-	.pwm45_fixup = false,
-	.has_clks = true,
-};
-
-static const struct mtk_pwm_platform_data mt7622_pwm_data = {
-	.num_pwms = 6,
 	.pwm45_fixup = false,
 	.has_clks = true,
 };
 
 static const struct mtk_pwm_platform_data mt7623_pwm_data = {
-	.num_pwms = 5,
 	.pwm45_fixup = true,
 	.has_clks = true,
 };
 
 static const struct mtk_pwm_platform_data mt7628_pwm_data = {
-	.num_pwms = 4,
 	.pwm45_fixup = true,
 	.has_clks = false,
 };
 
 static const struct of_device_id mtk_pwm_of_match[] = {
 	{ .compatible = "mediatek,mt2712-pwm", .data = &mt2712_pwm_data },
-	{ .compatible = "mediatek,mt7622-pwm", .data = &mt7622_pwm_data },
+	{ .compatible = "mediatek,mt7622-pwm", .data = &mt2712_pwm_data },
 	{ .compatible = "mediatek,mt7623-pwm", .data = &mt7623_pwm_data },
 	{ .compatible = "mediatek,mt7628-pwm", .data = &mt7628_pwm_data },
 	{ },
-- 
1.9.1

[PATCH 2/5] dt-bindings: pwm: add a property "mediatek,num-pwms"

[Ryder Lee]

This adds a property "mediatek,num-pwms" in example so that we could
set the number of PWM channels via device tree.

Signed-off-by: Ryder Lee <ryder.lee@mediatek.com>
---
 Documentation/devicetree/bindings/pwm/pwm-mediatek.txt | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/Documentation/devicetree/bindings/pwm/pwm-mediatek.txt b/Documentation/devicetree/bindings/pwm/pwm-mediatek.txt
index 991728c..f9e2d1f 100644
--- a/Documentation/devicetree/bindings/pwm/pwm-mediatek.txt
+++ b/Documentation/devicetree/bindings/pwm/pwm-mediatek.txt
@@ -20,6 +20,7 @@ Required properties:
  - pinctrl-names: Must contain a "default" entry.
  - pinctrl-0: One property must exist for each entry in pinctrl-names.
    See pinctrl/pinctrl-bindings.txt for details of the property values.
+ - mediatek,num-pwms: the number of PWM channels.
 
 Example:
 	pwm0: pwm@11006000 {
@@ -37,4 +38,5 @@ Example:
 			      "pwm3", "pwm4", "pwm5";
 		pinctrl-names = "default";
 		pinctrl-0 = <&pwm0_pins>;
+		mediatek,num-pwms = <5>;
 	};
-- 
1.9.1

[PATCH 3/5] arm64: dts: mt7622: add a property "mediatek,num-pwms" for PWM

[Ryder Lee]

This adds a property "mediatek,num-pwms" for PWM controller.

Signed-off-by: Ryder Lee <ryder.lee@mediatek.com>
---
 arch/arm64/boot/dts/mediatek/mt7622.dtsi | 1 +
 1 file changed, 1 insertion(+)

diff --git a/arch/arm64/boot/dts/mediatek/mt7622.dtsi b/arch/arm64/boot/dts/mediatek/mt7622.dtsi
index 8fc4aa7..ab016cf 100644
--- a/arch/arm64/boot/dts/mediatek/mt7622.dtsi
+++ b/arch/arm64/boot/dts/mediatek/mt7622.dtsi
@@ -436,6 +436,7 @@
 			 <&pericfg CLK_PERI_PWM6_PD>;
 		clock-names = "top", "main", "pwm1", "pwm2", "pwm3", "pwm4",
 			      "pwm5", "pwm6";
+		mediatek,num-pwms = <6>;
 		status = "disabled";
 	};
 
-- 
1.9.1

[PATCH 4/5] arm: dts: mt7623: add a property "mediatek,num-pwms" for PWM

[Ryder Lee]

This adds a property "mediatek,num-pwms" for PWM controller.

Signed-off-by: Ryder Lee <ryder.lee@mediatek.com>
---
 arch/arm/boot/dts/mt7623.dtsi | 1 +
 1 file changed, 1 insertion(+)

diff --git a/arch/arm/boot/dts/mt7623.dtsi b/arch/arm/boot/dts/mt7623.dtsi
index 98f1159..2dd2f93 100644
--- a/arch/arm/boot/dts/mt7623.dtsi
+++ b/arch/arm/boot/dts/mt7623.dtsi
@@ -443,6 +443,7 @@
 			 <&pericfg CLK_PERI_PWM5>;
 		clock-names = "top", "main", "pwm1", "pwm2",
 			      "pwm3", "pwm4", "pwm5";
+		mediatek,num-pwms = <5>;
 		status = "disabled";
 	};
 
-- 
1.9.1

[PATCH 5/5] dt-bindings: pwm: update bindings for MT7629 SoC

[Ryder Lee]

This updates bindings for MT7629 pwm controller.

Signed-off-by: Ryder Lee <ryder.lee@mediatek.com>
---
 Documentation/devicetree/bindings/pwm/pwm-mediatek.txt | 1 +
 1 file changed, 1 insertion(+)

diff --git a/Documentation/devicetree/bindings/pwm/pwm-mediatek.txt b/Documentation/devicetree/bindings/pwm/pwm-mediatek.txt
index f9e2d1f..f7e7784 100644
--- a/Documentation/devicetree/bindings/pwm/pwm-mediatek.txt
+++ b/Documentation/devicetree/bindings/pwm/pwm-mediatek.txt
@@ -6,6 +6,7 @@ Required properties:
    - "mediatek,mt7622-pwm": found on mt7622 SoC.
    - "mediatek,mt7623-pwm": found on mt7623 SoC.
    - "mediatek,mt7628-pwm": found on mt7628 SoC.
+   - "mediatek,mt7629-pwm", "mediatek,mt7622-pwm": found on mt7629 SoC.
  - reg: physical base address and length of the controller's registers.
  - #pwm-cells: must be 2. See pwm.txt in this directory for a description of
    the cell format.
-- 
1.9.1

Re: [PATCH 1/5] pwm: mediatek: add a property "mediatek,num-pwms"

[Matthias Brugger]

On 14/01/2019 09:21, Ryder Lee wrote:
> This adds a property "mediatek,num-pwms" to avoid having an endless
> list of compatibles with no other differences for the same driver.
> 
> Signed-off-by: Ryder Lee <ryder.lee@mediatek.com>
> ---
>  drivers/pwm/pwm-mediatek.c | 25 +++++++++++--------------
>  1 file changed, 11 insertions(+), 14 deletions(-)
> 
> diff --git a/drivers/pwm/pwm-mediatek.c b/drivers/pwm/pwm-mediatek.c
> index eb6674c..37daa84 100644
> --- a/drivers/pwm/pwm-mediatek.c
> +++ b/drivers/pwm/pwm-mediatek.c
> @@ -55,7 +55,6 @@ enum {
>  };
>  
>  struct mtk_pwm_platform_data {
> -	unsigned int num_pwms;
>  	bool pwm45_fixup;
>  	bool has_clks;
>  };
> @@ -226,10 +225,11 @@ static void mtk_pwm_disable(struct pwm_chip *chip, struct pwm_device *pwm)
>  
>  static int mtk_pwm_probe(struct platform_device *pdev)
>  {
> +	struct device_node *np = pdev->dev.of_node;
>  	const struct mtk_pwm_platform_data *data;
>  	struct mtk_pwm_chip *pc;
>  	struct resource *res;
> -	unsigned int i;
> +	unsigned int i, num_pwms;
>  	int ret;
>  
>  	pc = devm_kzalloc(&pdev->dev, sizeof(*pc), GFP_KERNEL);
> @@ -246,7 +246,13 @@ static int mtk_pwm_probe(struct platform_device *pdev)
>  	if (IS_ERR(pc->regs))
>  		return PTR_ERR(pc->regs);
>  
> -	for (i = 0; i < data->num_pwms + 2 && pc->soc->has_clks; i++) {
> +	ret = of_property_read_u32(np, "mediatek,num-pwms", &num_pwms);
> +	if (ret < 0) {
> +		dev_err(&pdev->dev, "failed to get pwm number: %d\n", ret);
> +		return ret;
> +	}
> +
> +	for (i = 0; i < num_pwms + 2 && pc->soc->has_clks; i++) {
>  		pc->clks[i] = devm_clk_get(&pdev->dev, mtk_pwm_clk_name[i]);
>  		if (IS_ERR(pc->clks[i])) {
>  			dev_err(&pdev->dev, "clock: %s fail: %ld\n",
> @@ -260,7 +266,7 @@ static int mtk_pwm_probe(struct platform_device *pdev)
>  	pc->chip.dev = &pdev->dev;
>  	pc->chip.ops = &mtk_pwm_ops;
>  	pc->chip.base = -1;
> -	pc->chip.npwm = data->num_pwms;
> +	pc->chip.npwm = num_pwms;
>  
>  	ret = pwmchip_add(&pc->chip);
>  	if (ret < 0) {
> @@ -279,32 +285,23 @@ static int mtk_pwm_remove(struct platform_device *pdev)
>  }
>  
>  static const struct mtk_pwm_platform_data mt2712_pwm_data = {
> -	.num_pwms = 8,
> -	.pwm45_fixup = false,
> -	.has_clks = true,
> -};
> -
> -static const struct mtk_pwm_platform_data mt7622_pwm_data = {
> -	.num_pwms = 6,
>  	.pwm45_fixup = false,
>  	.has_clks = true,
>  };

From my point of view that's not perfect. We should make sure that a newer
kernel does not break with an older device tree and vice versa.
Just imagine I use some board where u-boot passes the device tree to the kernel,
I update the kernel and PWM is broken.

So also it is crappy we will need to have the num_pwms variable for the older
boards.
Maybe put a switch in the probe function which checks the compatible with a
comment message saying that this is for legacy device tree, so that no new
contributer just copys the wrong code.

What do you think?
Regards,
Matthias

>  
>  static const struct mtk_pwm_platform_data mt7623_pwm_data = {
> -	.num_pwms = 5,
>  	.pwm45_fixup = true,
>  	.has_clks = true,
>  };
>  
>  static const struct mtk_pwm_platform_data mt7628_pwm_data = {
> -	.num_pwms = 4,
>  	.pwm45_fixup = true,
>  	.has_clks = false,
>  };
>  
>  static const struct of_device_id mtk_pwm_of_match[] = {
>  	{ .compatible = "mediatek,mt2712-pwm", .data = &mt2712_pwm_data },
> -	{ .compatible = "mediatek,mt7622-pwm", .data = &mt7622_pwm_data },
> +	{ .compatible = "mediatek,mt7622-pwm", .data = &mt2712_pwm_data },
>  	{ .compatible = "mediatek,mt7623-pwm", .data = &mt7623_pwm_data },
>  	{ .compatible = "mediatek,mt7628-pwm", .data = &mt7628_pwm_data },
>  	{ },
> 

Re: [PATCH 2/5] dt-bindings: pwm: add a property "mediatek,num-pwms"

[Matthias Brugger]

On 14/01/2019 09:21, Ryder Lee wrote:
> This adds a property "mediatek,num-pwms" in example so that we could
> set the number of PWM channels via device tree.
> 
> Signed-off-by: Ryder Lee <ryder.lee@mediatek.com>

Reviewed-by: Matthias Brugger <matthias.bgg@gmail.com>

> ---
>  Documentation/devicetree/bindings/pwm/pwm-mediatek.txt | 2 ++
>  1 file changed, 2 insertions(+)
> 
> diff --git a/Documentation/devicetree/bindings/pwm/pwm-mediatek.txt b/Documentation/devicetree/bindings/pwm/pwm-mediatek.txt
> index 991728c..f9e2d1f 100644
> --- a/Documentation/devicetree/bindings/pwm/pwm-mediatek.txt
> +++ b/Documentation/devicetree/bindings/pwm/pwm-mediatek.txt
> @@ -20,6 +20,7 @@ Required properties:
>   - pinctrl-names: Must contain a "default" entry.
>   - pinctrl-0: One property must exist for each entry in pinctrl-names.
>     See pinctrl/pinctrl-bindings.txt for details of the property values.
> + - mediatek,num-pwms: the number of PWM channels.
>  
>  Example:
>  	pwm0: pwm@11006000 {
> @@ -37,4 +38,5 @@ Example:
>  			      "pwm3", "pwm4", "pwm5";
>  		pinctrl-names = "default";
>  		pinctrl-0 = <&pwm0_pins>;
> +		mediatek,num-pwms = <5>;
>  	};
> 

Re: [PATCH 5/5] dt-bindings: pwm: update bindings for MT7629 SoC

[Matthias Brugger]

On 14/01/2019 09:21, Ryder Lee wrote:
> This updates bindings for MT7629 pwm controller.
> 
> Signed-off-by: Ryder Lee <ryder.lee@mediatek.com>

Reviewed-by: Matthias Brugger <matthias.bgg@gmail.com>

> ---
>  Documentation/devicetree/bindings/pwm/pwm-mediatek.txt | 1 +
>  1 file changed, 1 insertion(+)
> 
> diff --git a/Documentation/devicetree/bindings/pwm/pwm-mediatek.txt b/Documentation/devicetree/bindings/pwm/pwm-mediatek.txt
> index f9e2d1f..f7e7784 100644
> --- a/Documentation/devicetree/bindings/pwm/pwm-mediatek.txt
> +++ b/Documentation/devicetree/bindings/pwm/pwm-mediatek.txt
> @@ -6,6 +6,7 @@ Required properties:
>     - "mediatek,mt7622-pwm": found on mt7622 SoC.
>     - "mediatek,mt7623-pwm": found on mt7623 SoC.
>     - "mediatek,mt7628-pwm": found on mt7628 SoC.
> +   - "mediatek,mt7629-pwm", "mediatek,mt7622-pwm": found on mt7629 SoC.
>   - reg: physical base address and length of the controller's registers.
>   - #pwm-cells: must be 2. See pwm.txt in this directory for a description of
>     the cell format.
> 

Re: [PATCH 1/5] pwm: mediatek: add a property "mediatek,num-pwms"

[Uwe Kleine-König]

On Mon, Jan 14, 2019 at 04:21:20PM +0800, Ryder Lee wrote:
> This adds a property "mediatek,num-pwms" to avoid having an endless
> list of compatibles with no other differences for the same driver.

I seem to recall having said something similar before, but maybe this
was a different series (there is no v2 or higher in the Subject ...)

I think it would be sensible to drop the vendor prefix and go with plain
"num-pwms" (or "npwms" to align to "ngpios" in the gpio bindings).

> Signed-off-by: Ryder Lee <ryder.lee@mediatek.com>
> ---
>  drivers/pwm/pwm-mediatek.c | 25 +++++++++++--------------
>  1 file changed, 11 insertions(+), 14 deletions(-)
> 
> diff --git a/drivers/pwm/pwm-mediatek.c b/drivers/pwm/pwm-mediatek.c
> index eb6674c..37daa84 100644
> --- a/drivers/pwm/pwm-mediatek.c
> +++ b/drivers/pwm/pwm-mediatek.c
> @@ -55,7 +55,6 @@ enum {
>  };
>  
>  struct mtk_pwm_platform_data {
> -	unsigned int num_pwms;
>  	bool pwm45_fixup;
>  	bool has_clks;
>  };
> @@ -226,10 +225,11 @@ static void mtk_pwm_disable(struct pwm_chip *chip, struct pwm_device *pwm)
>  
>  static int mtk_pwm_probe(struct platform_device *pdev)
>  {
> +	struct device_node *np = pdev->dev.of_node;
>  	const struct mtk_pwm_platform_data *data;
>  	struct mtk_pwm_chip *pc;
>  	struct resource *res;
> -	unsigned int i;
> +	unsigned int i, num_pwms;
>  	int ret;
>  
>  	pc = devm_kzalloc(&pdev->dev, sizeof(*pc), GFP_KERNEL);
> @@ -246,7 +246,13 @@ static int mtk_pwm_probe(struct platform_device *pdev)
>  	if (IS_ERR(pc->regs))
>  		return PTR_ERR(pc->regs);
>  
> -	for (i = 0; i < data->num_pwms + 2 && pc->soc->has_clks; i++) {
> +	ret = of_property_read_u32(np, "mediatek,num-pwms", &num_pwms);
> +	if (ret < 0) {
> +		dev_err(&pdev->dev, "failed to get pwm number: %d\n", ret);

This sounds wrong. "Failed to get number of pwms" sounds better to my
(non-native) ear.

> +		return ret;
> +	}
> +
> +	for (i = 0; i < num_pwms + 2 && pc->soc->has_clks; i++) {
>  		pc->clks[i] = devm_clk_get(&pdev->dev, mtk_pwm_clk_name[i]);
>  		if (IS_ERR(pc->clks[i])) {
>  			dev_err(&pdev->dev, "clock: %s fail: %ld\n",
> @@ -260,7 +266,7 @@ static int mtk_pwm_probe(struct platform_device *pdev)
>  	pc->chip.dev = &pdev->dev;
>  	pc->chip.ops = &mtk_pwm_ops;
>  	pc->chip.base = -1;
> -	pc->chip.npwm = data->num_pwms;
> +	pc->chip.npwm = num_pwms;
>  
>  	ret = pwmchip_add(&pc->chip);
>  	if (ret < 0) {
> @@ -279,32 +285,23 @@ static int mtk_pwm_remove(struct platform_device *pdev)
>  }
>  
>  static const struct mtk_pwm_platform_data mt2712_pwm_data = {
> -	.num_pwms = 8,
> -	.pwm45_fixup = false,
> -	.has_clks = true,
> -};
> -
> -static const struct mtk_pwm_platform_data mt7622_pwm_data = {
> -	.num_pwms = 6,
>  	.pwm45_fixup = false,
>  	.has_clks = true,

I agree with Matthias Brugger that at least for some time you should be
able to fall back to the right number of pwms if the device tree doesn't
have a num-pwms property.

Best regards
Uwe

-- 
Pengutronix e.K.                           | Uwe Kleine-König            |
Industrial Linux Solutions                 | http://www.pengutronix.de/  |

Re: [PATCH 3/5] arm64: dts: mt7622: add a property "mediatek,num-pwms" for PWM

[Uwe Kleine-König]

Hello,

On Mon, Jan 14, 2019 at 04:21:22PM +0800, Ryder Lee wrote:
> This adds a property "mediatek,num-pwms" for PWM controller.
> 
> Signed-off-by: Ryder Lee <ryder.lee@mediatek.com>
> ---
>  arch/arm64/boot/dts/mediatek/mt7622.dtsi | 1 +
>  1 file changed, 1 insertion(+)
> 
> diff --git a/arch/arm64/boot/dts/mediatek/mt7622.dtsi b/arch/arm64/boot/dts/mediatek/mt7622.dtsi
> index 8fc4aa7..ab016cf 100644
> --- a/arch/arm64/boot/dts/mediatek/mt7622.dtsi
> +++ b/arch/arm64/boot/dts/mediatek/mt7622.dtsi
> @@ -436,6 +436,7 @@
>  			 <&pericfg CLK_PERI_PWM6_PD>;
>  		clock-names = "top", "main", "pwm1", "pwm2", "pwm3", "pwm4",
>  			      "pwm5", "pwm6";
> +		mediatek,num-pwms = <6>;
>  		status = "disabled";

Conceptually this patch must go in before the change to the driver.
Otherwise the pwms are not usable with only patch 1 applied which breaks
bisectability.

Best regards
Uwe

-- 
Pengutronix e.K.                           | Uwe Kleine-König            |
Industrial Linux Solutions                 | http://www.pengutronix.de/  |

Re: [PATCH 3/5] arm64: dts: mt7622: add a property "mediatek,num-pwms" for PWM

[Matthias Brugger]

On 15/01/2019 21:02, Uwe Kleine-König wrote:
> Hello,
> 
> On Mon, Jan 14, 2019 at 04:21:22PM +0800, Ryder Lee wrote:
>> This adds a property "mediatek,num-pwms" for PWM controller.
>>
>> Signed-off-by: Ryder Lee <ryder.lee@mediatek.com>
>> ---
>>  arch/arm64/boot/dts/mediatek/mt7622.dtsi | 1 +
>>  1 file changed, 1 insertion(+)
>>
>> diff --git a/arch/arm64/boot/dts/mediatek/mt7622.dtsi b/arch/arm64/boot/dts/mediatek/mt7622.dtsi
>> index 8fc4aa7..ab016cf 100644
>> --- a/arch/arm64/boot/dts/mediatek/mt7622.dtsi
>> +++ b/arch/arm64/boot/dts/mediatek/mt7622.dtsi
>> @@ -436,6 +436,7 @@
>>  			 <&pericfg CLK_PERI_PWM6_PD>;
>>  		clock-names = "top", "main", "pwm1", "pwm2", "pwm3", "pwm4",
>>  			      "pwm5", "pwm6";
>> +		mediatek,num-pwms = <6>;
>>  		status = "disabled";
> 
> Conceptually this patch must go in before the change to the driver.
> Otherwise the pwms are not usable with only patch 1 applied which breaks
> bisectability.
> 

The driver should have backwards compatibility to older DTs. So that would need
to be fixed in the driver not in the patch order of the series.

Regards,
Matthias

Re: [PATCH 3/5] arm64: dts: mt7622: add a property "mediatek,num-pwms" for PWM

[Uwe Kleine-König]

Hello,

On Thu, Jan 17, 2019 at 02:00:43PM +0100, Matthias Brugger wrote:
> On 15/01/2019 21:02, Uwe Kleine-König wrote:
> > On Mon, Jan 14, 2019 at 04:21:22PM +0800, Ryder Lee wrote:
> >> diff --git a/arch/arm64/boot/dts/mediatek/mt7622.dtsi b/arch/arm64/boot/dts/mediatek/mt7622.dtsi
> >> index 8fc4aa7..ab016cf 100644
> >> --- a/arch/arm64/boot/dts/mediatek/mt7622.dtsi
> >> +++ b/arch/arm64/boot/dts/mediatek/mt7622.dtsi
> >> @@ -436,6 +436,7 @@
> >>  			 <&pericfg CLK_PERI_PWM6_PD>;
> >>  		clock-names = "top", "main", "pwm1", "pwm2", "pwm3", "pwm4",
> >>  			      "pwm5", "pwm6";
> >> +		mediatek,num-pwms = <6>;
> >>  		status = "disabled";
> > 
> > Conceptually this patch must go in before the change to the driver.
> > Otherwise the pwms are not usable with only patch 1 applied which breaks
> > bisectability.
> > 
> 
> The driver should have backwards compatibility to older DTs. So that would need
> to be fixed in the driver not in the patch order of the series.

Right you are. Bisectability is a reason to not apply the patches in the
order as is, but given that you already requested backwards
compatibility the bisectability will be fixed en passant.

Best regards
Uwe

-- 
Pengutronix e.K.                           | Uwe Kleine-König            |
Industrial Linux Solutions                 | http://www.pengutronix.de/  |

Re: [PATCH 1/5] pwm: mediatek: add a property "mediatek,num-pwms"

[Ryder Lee]

On Mon, 2019-01-14 at 12:16 +0100, Matthias Brugger wrote:
> 
> On 14/01/2019 09:21, Ryder Lee wrote:
> > This adds a property "mediatek,num-pwms" to avoid having an endless
> > list of compatibles with no other differences for the same driver.
> > 
> > Signed-off-by: Ryder Lee <ryder.lee@mediatek.com>
> > ---
> >  drivers/pwm/pwm-mediatek.c | 25 +++++++++++--------------
> >  1 file changed, 11 insertions(+), 14 deletions(-)
> > 
> > diff --git a/drivers/pwm/pwm-mediatek.c b/drivers/pwm/pwm-mediatek.c
> > index eb6674c..37daa84 100644
> > --- a/drivers/pwm/pwm-mediatek.c
> > +++ b/drivers/pwm/pwm-mediatek.c
> > @@ -55,7 +55,6 @@ enum {
> >  };
> >  
> >  struct mtk_pwm_platform_data {
> > -	unsigned int num_pwms;
> >  	bool pwm45_fixup;
> >  	bool has_clks;
> >  };
> > @@ -226,10 +225,11 @@ static void mtk_pwm_disable(struct pwm_chip *chip, struct pwm_device *pwm)
> >  
> >  static int mtk_pwm_probe(struct platform_device *pdev)
> >  {
> > +	struct device_node *np = pdev->dev.of_node;
> >  	const struct mtk_pwm_platform_data *data;
> >  	struct mtk_pwm_chip *pc;
> >  	struct resource *res;
> > -	unsigned int i;
> > +	unsigned int i, num_pwms;
> >  	int ret;
> >  
> >  	pc = devm_kzalloc(&pdev->dev, sizeof(*pc), GFP_KERNEL);
> > @@ -246,7 +246,13 @@ static int mtk_pwm_probe(struct platform_device *pdev)
> >  	if (IS_ERR(pc->regs))
> >  		return PTR_ERR(pc->regs);
> >  
> > -	for (i = 0; i < data->num_pwms + 2 && pc->soc->has_clks; i++) {
> > +	ret = of_property_read_u32(np, "mediatek,num-pwms", &num_pwms);
> > +	if (ret < 0) {
> > +		dev_err(&pdev->dev, "failed to get pwm number: %d\n", ret);
> > +		return ret;
> > +	}
> > +
> > +	for (i = 0; i < num_pwms + 2 && pc->soc->has_clks; i++) {
> >  		pc->clks[i] = devm_clk_get(&pdev->dev, mtk_pwm_clk_name[i]);
> >  		if (IS_ERR(pc->clks[i])) {
> >  			dev_err(&pdev->dev, "clock: %s fail: %ld\n",
> > @@ -260,7 +266,7 @@ static int mtk_pwm_probe(struct platform_device *pdev)
> >  	pc->chip.dev = &pdev->dev;
> >  	pc->chip.ops = &mtk_pwm_ops;
> >  	pc->chip.base = -1;
> > -	pc->chip.npwm = data->num_pwms;
> > +	pc->chip.npwm = num_pwms;
> >  
> >  	ret = pwmchip_add(&pc->chip);
> >  	if (ret < 0) {
> > @@ -279,32 +285,23 @@ static int mtk_pwm_remove(struct platform_device *pdev)
> >  }
> >  
> >  static const struct mtk_pwm_platform_data mt2712_pwm_data = {
> > -	.num_pwms = 8,
> > -	.pwm45_fixup = false,
> > -	.has_clks = true,
> > -};
> > -
> > -static const struct mtk_pwm_platform_data mt7622_pwm_data = {
> > -	.num_pwms = 6,
> >  	.pwm45_fixup = false,
> >  	.has_clks = true,
> >  };
> 
> From my point of view that's not perfect. We should make sure that a newer
> kernel does not break with an older device tree and vice versa.
> Just imagine I use some board where u-boot passes the device tree to the kernel,
> I update the kernel and PWM is broken.
> 
> So also it is crappy we will need to have the num_pwms variable for the older
> boards.
> Maybe put a switch in the probe function which checks the compatible with a
> comment message saying that this is for legacy device tree, so that no new
> contributer just copys the wrong code.
> 
> What do you think?

Okay, I will do that.

Ryder
> 
> >  
> >  static const struct mtk_pwm_platform_data mt7623_pwm_data = {
> > -	.num_pwms = 5,
> >  	.pwm45_fixup = true,
> >  	.has_clks = true,
> >  };
> >  
> >  static const struct mtk_pwm_platform_data mt7628_pwm_data = {
> > -	.num_pwms = 4,
> >  	.pwm45_fixup = true,
> >  	.has_clks = false,
> >  };
> >  
> >  static const struct of_device_id mtk_pwm_of_match[] = {
> >  	{ .compatible = "mediatek,mt2712-pwm", .data = &mt2712_pwm_data },
> > -	{ .compatible = "mediatek,mt7622-pwm", .data = &mt7622_pwm_data },
> > +	{ .compatible = "mediatek,mt7622-pwm", .data = &mt2712_pwm_data },
> >  	{ .compatible = "mediatek,mt7623-pwm", .data = &mt7623_pwm_data },
> >  	{ .compatible = "mediatek,mt7628-pwm", .data = &mt7628_pwm_data },
> >  	{ },
> >