[PATCH v3 1/6] Documentation: ARM: sunxi: pwm: add Allwinner sun8i.

[PATCH v3 1/6] Documentation: ARM: sunxi: pwm: add Allwinner sun8i.

[Hao Zhang]

This patch adds Allwinner sun8i pwm binding document.

Signed-off-by: Hao Zhang <hao5781286@gmail.com>
---
 .../devicetree/bindings/pwm/pwm-sun8i.txt          | 24 ++++++++++++++++++++++
 1 file changed, 24 insertions(+)
 create mode 100644 Documentation/devicetree/bindings/pwm/pwm-sun8i.txt

diff --git a/Documentation/devicetree/bindings/pwm/pwm-sun8i.txt b/Documentation/devicetree/bindings/pwm/pwm-sun8i.txt
new file mode 100644
index 0000000..7531d85
--- /dev/null
+++ b/Documentation/devicetree/bindings/pwm/pwm-sun8i.txt
@@ -0,0 +1,24 @@
+Allwinner sun8i R40/V40/T3 SoC PWM controller
+
+Required properties:
+  - compatible: Should be one of:
+    - "allwinner,sun8i-r40-pwm"
+  - reg: Physical base address and length of the controller's registers
+  - interrupts: Should contain interrupt.
+  - clocks: From common clock binding, handle to the parent clock.
+  - clock-names: Must contain the clock names described just above.
+  - pwm-channels: PWM channels of the controller.
+  - #pwm-cells: Should be 3. See pwm.txt in this directory for a description of
+    the cells format.
+
+Example:
+
+pwm: pwm@1c23400 {
+	     compatible = "allwinner,sun8i-r40-pwm";
+	     reg = <0x01c23400 0x400>;
+	     interrupts = <GIC_SPI 47 IRQ_TYPE_LEVEL_HIGH>;
+	     clocks = <&osc24M>, <&ccu CLK_APB1>;
+	     clock-names = "mux-0", "mux-1";
+	     pwm-channels = <8>;
+	     #pwm-cells = <3>;
+};
-- 
2.7.4

Re: [PATCH v3 1/6] Documentation: ARM: sunxi: pwm: add Allwinner sun8i.

[Rob Herring]

On Mon, 26 Nov 2018 00:18:59 +0800, Hao Zhang wrote:
> This patch adds Allwinner sun8i pwm binding document.
> 
> Signed-off-by: Hao Zhang <hao5781286@gmail.com>
> ---
>  .../devicetree/bindings/pwm/pwm-sun8i.txt          | 24 ++++++++++++++++++++++
>  1 file changed, 24 insertions(+)
>  create mode 100644 Documentation/devicetree/bindings/pwm/pwm-sun8i.txt
> 

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

Re: [PATCH v3 1/6] Documentation: ARM: sunxi: pwm: add Allwinner sun8i.

[Uwe Kleine-König]

Hello,

On Mon, Nov 26, 2018 at 12:18:59AM +0800, Hao Zhang wrote:
> This patch adds Allwinner sun8i pwm binding document.
> 
> Signed-off-by: Hao Zhang <hao5781286@gmail.com>
> ---
>  .../devicetree/bindings/pwm/pwm-sun8i.txt          | 24 ++++++++++++++++++++++
>  1 file changed, 24 insertions(+)
>  create mode 100644 Documentation/devicetree/bindings/pwm/pwm-sun8i.txt
> 
> diff --git a/Documentation/devicetree/bindings/pwm/pwm-sun8i.txt b/Documentation/devicetree/bindings/pwm/pwm-sun8i.txt
> new file mode 100644
> index 0000000..7531d85
> --- /dev/null
> +++ b/Documentation/devicetree/bindings/pwm/pwm-sun8i.txt
> @@ -0,0 +1,24 @@
> +Allwinner sun8i R40/V40/T3 SoC PWM controller
> +
> +Required properties:
> +  - compatible: Should be one of:
> +    - "allwinner,sun8i-r40-pwm"
> +  - reg: Physical base address and length of the controller's registers
> +  - interrupts: Should contain interrupt.
> +  - clocks: From common clock binding, handle to the parent clock.
> +  - clock-names: Must contain the clock names described just above.
> +  - pwm-channels: PWM channels of the controller.
> +  - #pwm-cells: Should be 3. See pwm.txt in this directory for a description of
> +    the cells format.

I wonder why "interrupts" is needed here. I guess this is only needed
for waveform capture? Is this only "optional"? The driver doesn't use
it.

Apart from this interrupts property this is all pretty standard and I
wonder if we could merge several documents into one.

For example Documentation/devicetree/bindings/pwm/pwm-st.txt looks
identically apart from "pwm-channels" being called "st,pwm-num-chan"
there. (It even has an interrupts property. Should the st driver move to
"pwm-channels", too?)

Best regards
Uwe

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

Re: [PATCH v3 1/6] Documentation: ARM: sunxi: pwm: add Allwinner sun8i.

[Maxime Ripard]

On Mon, Nov 26, 2018 at 12:18:59AM +0800, Hao Zhang wrote:
> This patch adds Allwinner sun8i pwm binding document.
> 
> Signed-off-by: Hao Zhang <hao5781286@gmail.com>
> ---
>  .../devicetree/bindings/pwm/pwm-sun8i.txt          | 24 ++++++++++++++++++++++
>  1 file changed, 24 insertions(+)
>  create mode 100644 Documentation/devicetree/bindings/pwm/pwm-sun8i.txt
> 
> diff --git a/Documentation/devicetree/bindings/pwm/pwm-sun8i.txt b/Documentation/devicetree/bindings/pwm/pwm-sun8i.txt
> new file mode 100644
> index 0000000..7531d85
> --- /dev/null
> +++ b/Documentation/devicetree/bindings/pwm/pwm-sun8i.txt
> @@ -0,0 +1,24 @@
> +Allwinner sun8i R40/V40/T3 SoC PWM controller
> +
> +Required properties:
> +  - compatible: Should be one of:
> +    - "allwinner,sun8i-r40-pwm"
> +  - reg: Physical base address and length of the controller's registers
> +  - interrupts: Should contain interrupt.
> +  - clocks: From common clock binding, handle to the parent clock.
> +  - clock-names: Must contain the clock names described just above.

You didn't describe those names in that document.

You seem to have used mux-0 and mux-1 for the clock names. I guess we
don't have to use a name there, we can simply use the position to find
out (as long as it's documented in the binding)

Maxime

-- 
Maxime Ripard, Bootlin
Embedded Linux and Kernel engineering
https://bootlin.com

Re: [PATCH v3 1/6] Documentation: ARM: sunxi: pwm: add Allwinner sun8i.

[Uwe Kleine-König]

Hello,

On Tue, Nov 27, 2018 at 08:52:26AM +0100, Maxime Ripard wrote:
> On Mon, Nov 26, 2018 at 12:18:59AM +0800, Hao Zhang wrote:
> > +  - clocks: From common clock binding, handle to the parent clock.
> > +  - clock-names: Must contain the clock names described just above.
> 
> [...]
> 
> You seem to have used mux-0 and mux-1 for the clock names. I guess we
> don't have to use a name there, we can simply use the position to find
> out (as long as it's documented in the binding)

I also wondered if the driver relies on the fact that the second clock
is the faster running one. Is this sensible?

Best regards
Uwe

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

Re: [PATCH v3 1/6] Documentation: ARM: sunxi: pwm: add Allwinner sun8i.

[Maxime Ripard]

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On Tue, Nov 27, 2018 at 09:35:23AM +0100, Uwe Kleine-König wrote:
> Hello,
> 
> On Tue, Nov 27, 2018 at 08:52:26AM +0100, Maxime Ripard wrote:
> > On Mon, Nov 26, 2018 at 12:18:59AM +0800, Hao Zhang wrote:
> > > +  - clocks: From common clock binding, handle to the parent clock.
> > > +  - clock-names: Must contain the clock names described just above.
> > 
> > [...]
> > 
> > You seem to have used mux-0 and mux-1 for the clock names. I guess we
> > don't have to use a name there, we can simply use the position to find
> > out (as long as it's documented in the binding)
> 
> I also wondered if the driver relies on the fact that the second clock
> is the faster running one. Is this sensible?

Not really, I'm not sure we can make those expectations in the DT
binding, especially since clock rate can change at runtime.

Maxime

-- 
Maxime Ripard, Bootlin
Embedded Linux and Kernel engineering
https://bootlin.com

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Re: [PATCH v3 1/6] Documentation: ARM: sunxi: pwm: add Allwinner sun8i.

[Maxime Ripard]

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Hi!

(Please keep all the recipiens in Cc)

On Sun, Dec 02, 2018 at 12:13:21AM +0800, Hao Zhang wrote:
> Maxime Ripard <maxime.ripard@bootlin.com> 于2018年11月27日周二 下午6:33写道：
> >
> > On Tue, Nov 27, 2018 at 09:35:23AM +0100, Uwe Kleine-König wrote:
> > > Hello,
> > >
> > > On Tue, Nov 27, 2018 at 08:52:26AM +0100, Maxime Ripard wrote:
> > > > On Mon, Nov 26, 2018 at 12:18:59AM +0800, Hao Zhang wrote:
> > > > > +  - clocks: From common clock binding, handle to the parent clock.
> > > > > +  - clock-names: Must contain the clock names described just above.
> > > >
> > > > [...]
> > > >
> > > > You seem to have used mux-0 and mux-1 for the clock names. I guess we
> > > > don't have to use a name there, we can simply use the position to find
> > > > out (as long as it's documented in the binding)
> > >
> > > I also wondered if the driver relies on the fact that the second clock
> > > is the faster running one. Is this sensible?
> >
> > Not really, I'm not sure we can make those expectations in the DT
> > binding, especially since clock rate can change at runtime.
>
> How about just add one clock on DT, most of the time, 24MHZ is enough
> (apb1 is 100MHZ)
> other one just use as a optional.
> clock rate change at runtime would make the same pair pwm channel
> uncontrollable,
> because previous one would be change by the new one different setting.

The DT is a hardware representation. If the hardware block can use
both clocks, it should be described.

Now, you can totally use only one clock of these 2 in your driver if that's
easier / more reasonable.

Maxime

-- 
Maxime Ripard, Bootlin
Embedded Linux and Kernel engineering
https://bootlin.com

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Re: [PATCH v3 1/6] Documentation: ARM: sunxi: pwm: add Allwinner sun8i.

[Thierry Reding]

[-- Attachment #1: Type: text/plain, Size: 1289 bytes --]

On Mon, Nov 26, 2018 at 12:18:59AM +0800, Hao Zhang wrote:
> This patch adds Allwinner sun8i pwm binding document.
> 
> Signed-off-by: Hao Zhang <hao5781286@gmail.com>
> ---
>  .../devicetree/bindings/pwm/pwm-sun8i.txt          | 24 ++++++++++++++++++++++
>  1 file changed, 24 insertions(+)
>  create mode 100644 Documentation/devicetree/bindings/pwm/pwm-sun8i.txt
> 
> diff --git a/Documentation/devicetree/bindings/pwm/pwm-sun8i.txt b/Documentation/devicetree/bindings/pwm/pwm-sun8i.txt
> new file mode 100644
> index 0000000..7531d85
> --- /dev/null
> +++ b/Documentation/devicetree/bindings/pwm/pwm-sun8i.txt
> @@ -0,0 +1,24 @@
> +Allwinner sun8i R40/V40/T3 SoC PWM controller
> +
> +Required properties:
> +  - compatible: Should be one of:
> +    - "allwinner,sun8i-r40-pwm"
> +  - reg: Physical base address and length of the controller's registers
> +  - interrupts: Should contain interrupt.
> +  - clocks: From common clock binding, handle to the parent clock.
> +  - clock-names: Must contain the clock names described just above.
> +  - pwm-channels: PWM channels of the controller.

Why do you need this? In the cover letter you say:

	"The sun8i R40/T3/V40 PWM has 8 PWM channals ..."

Why does this need to be specified in the DT?

Thierry

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Fwd: [PATCH v3 1/6] Documentation: ARM: sunxi: pwm: add Allwinner sun8i.

[Hao Zhang]

---------- Forwarded message ---------
From: Hao Zhang <hao5781286@gmail.com>
Date: 2019年3月12日周二 下午12:59
Subject: Re: [PATCH v3 1/6] Documentation: ARM: sunxi: pwm: add Allwinner sun8i.
To: Thierry Reding <thierry.reding@gmail.com>


Thierry Reding <thierry.reding@gmail.com> 于2018年12月21日周五 上午1:50写道：
>
> On Mon, Nov 26, 2018 at 12:18:59AM +0800, Hao Zhang wrote:
> > This patch adds Allwinner sun8i pwm binding document.
> >
> > Signed-off-by: Hao Zhang <hao5781286@gmail.com>
> > ---
> >  .../devicetree/bindings/pwm/pwm-sun8i.txt          | 24 ++++++++++++++++++++++
> >  1 file changed, 24 insertions(+)
> >  create mode 100644 Documentation/devicetree/bindings/pwm/pwm-sun8i.txt
> >
> > diff --git a/Documentation/devicetree/bindings/pwm/pwm-sun8i.txt b/Documentation/devicetree/bindings/pwm/pwm-sun8i.txt
> > new file mode 100644
> > index 0000000..7531d85
> > --- /dev/null
> > +++ b/Documentation/devicetree/bindings/pwm/pwm-sun8i.txt
> > @@ -0,0 +1,24 @@
> > +Allwinner sun8i R40/V40/T3 SoC PWM controller
> > +
> > +Required properties:
> > +  - compatible: Should be one of:
> > +    - "allwinner,sun8i-r40-pwm"
> > +  - reg: Physical base address and length of the controller's registers
> > +  - interrupts: Should contain interrupt.
> > +  - clocks: From common clock binding, handle to the parent clock.
> > +  - clock-names: Must contain the clock names described just above.
> > +  - pwm-channels: PWM channels of the controller.
>
> Why do you need this? In the cover letter you say:
>
>         "The sun8i R40/T3/V40 PWM has 8 PWM channals ..."
>
> Why does this need to be specified in the DT?

T3 PWM has 8 channals, i think it is necessary to tell user how to
specify it Instead of
hardcode the channal myself :)

Thanks for review :)

>
> Thierry
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