by Maxime Jourdan

[permalink] [raw]

Subject: Re: [PATCH v2 2/4] dt-bindings: soc: amlogic: add meson-canvas documentation

2018-08-13 21:07 GMT+02:00 Rob Herring <[email protected]>:
> On Wed, Aug 08, 2018 at 12:00:09AM +0200, Maxime Jourdan wrote:
>> DT bindings doc for amlogic,meson-canvas
>>
>> Signed-off-by: Maxime Jourdan <[email protected]>
>> ---
>> .../soc/amlogic/amlogic,meson-canvas.txt | 36 +++++++++++++++++++
>> 1 file changed, 36 insertions(+)
>> create mode 100644 Documentation/devicetree/bindings/soc/amlogic/amlogic,meson-canvas.txt
>>
>> diff --git a/Documentation/devicetree/bindings/soc/amlogic/amlogic,meson-canvas.txt b/Documentation/devicetree/bindings/soc/amlogic/amlogic,meson-canvas.txt
>> new file mode 100644
>> index 000000000000..5f0351717bee
>> --- /dev/null
>> +++ b/Documentation/devicetree/bindings/soc/amlogic/amlogic,meson-canvas.txt
>> @@ -0,0 +1,36 @@
>> +Amlogic Canvas
>> +================================
>> +
>> +A canvas is a collection of metadata that describes a pixel buffer.
>> +Those metadata include: width, height, phyaddr, wrapping, block mode
>> +and endianness.
>> +
>> +Many IPs within Amlogic SoCs rely on canvas indexes to read/write pixel data
>> +rather than use the phy addresses directly. For instance, this is the case for
>> +the video decoders and the display.
>> +
>> +Amlogic SoCs have 256 canvas.
>> +
>> +Device Tree Bindings:
>> +---------------------
>> +
>> +Canvas Provider
>> +--------------------------
>> +
>> +Required properties:
>> +- compatible: "amlogic,canvas"
>> +
>> +Parent node should have the following properties :
>> +- compatible: "amlogic,gx-dmc-sysctrl", "syscon", "simple-mfd"
>
> Is this documented somewhere? One child function is not a reason for an
> MFD and child nodes. And child nodes like this with no resources are
> unnecessary.
>

Hi Rob, this was done to follow the same path as other buses on the
platform that have sysctrls in order to provide regmaps to the
devices.

I can see how it's not really necessary here though, would it be okay
with you if I turned "canvas" into a simple bus subnode, using __iomem
in the device ?

>> +- reg: base address and size of the DMC system control register space.
>> +
>> +Example:
>> +
>> +sysctrl_DMC: system-controller@0 {
>> + compatible = "amlogic,gx-dmc-sysctrl", "syscon", "simple-mfd";
>> + reg = <0x0 0x0 0x0 0x1000>;
>> +
>> + canvas: canvas-provider@0 {
>> + compatible = "amlogic,canvas";
>> + };
>> +};
>> --
>> 2.18.0
>>
>> --
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2018-08-14 14:42:06

by Rob Herring (Arm)

[permalink] [raw]

Subject: Re: [PATCH v2 2/4] dt-bindings: soc: amlogic: add meson-canvas documentation

On Mon, Aug 13, 2018 at 8:42 PM Maxime Jourdan <[email protected]> wrote:
>
> 2018-08-13 21:07 GMT+02:00 Rob Herring <[email protected]>:
> > On Wed, Aug 08, 2018 at 12:00:09AM +0200, Maxime Jourdan wrote:
> >> DT bindings doc for amlogic,meson-canvas
> >>
> >> Signed-off-by: Maxime Jourdan <[email protected]>
> >> ---
> >> .../soc/amlogic/amlogic,meson-canvas.txt | 36 +++++++++++++++++++
> >> 1 file changed, 36 insertions(+)
> >> create mode 100644 Documentation/devicetree/bindings/soc/amlogic/amlogic,meson-canvas.txt
> >>
> >> diff --git a/Documentation/devicetree/bindings/soc/amlogic/amlogic,meson-canvas.txt b/Documentation/devicetree/bindings/soc/amlogic/amlogic,meson-canvas.txt
> >> new file mode 100644
> >> index 000000000000..5f0351717bee
> >> --- /dev/null
> >> +++ b/Documentation/devicetree/bindings/soc/amlogic/amlogic,meson-canvas.txt
> >> @@ -0,0 +1,36 @@
> >> +Amlogic Canvas
> >> +================================
> >> +
> >> +A canvas is a collection of metadata that describes a pixel buffer.
> >> +Those metadata include: width, height, phyaddr, wrapping, block mode
> >> +and endianness.
> >> +
> >> +Many IPs within Amlogic SoCs rely on canvas indexes to read/write pixel data
> >> +rather than use the phy addresses directly. For instance, this is the case for
> >> +the video decoders and the display.
> >> +
> >> +Amlogic SoCs have 256 canvas.
> >> +
> >> +Device Tree Bindings:
> >> +---------------------
> >> +
> >> +Canvas Provider
> >> +--------------------------
> >> +
> >> +Required properties:
> >> +- compatible: "amlogic,canvas"
> >> +
> >> +Parent node should have the following properties :
> >> +- compatible: "amlogic,gx-dmc-sysctrl", "syscon", "simple-mfd"
> >
> > Is this documented somewhere? One child function is not a reason for an
> > MFD and child nodes. And child nodes like this with no resources are
> > unnecessary.
> >
>
> Hi Rob, this was done to follow the same path as other buses on the
> platform that have sysctrls in order to provide regmaps to the
> devices.
>
> I can see how it's not really necessary here though, would it be okay
> with you if I turned "canvas" into a simple bus subnode, using __iomem
> in the device ?

That's a driver issue that has little to do with the binding. You can
create a regmap for any node, "syscon" just does that automagically
for you.

Rob