Re: [RFC v2 2/4] dt-bindings: i2c: mux: demux-pinctrl: add bindings

2016-01-07 Thread Jan Lübbe 
Hi Wolfram,

On Mi, 2016-01-06 at 14:51 +0100, Wolfram Sang wrote:
[...]
> +Required properties:
> +- compatible: "i2c-demux-pinctrl"
> +- i2c-parent: List of phandles of I2C masters available for selection. The 
> first
> +   one will be used as default.
> +- i2c-bus-name: The name of this bus. Also needed as pinctrl-name for the I2C
> + parents.
[...]
> + i2chdmi: i2c@8 {
> + compatible = "i2c-demux-pinctrl";
> + i2c-parent = <>, <>, <>;
> + i2c-bus-name = "i2c-hdmi";
> + #address-cells = <1>;
> + #size-cells = <0>;
[...]
> + gpioi2c: i2c@9 {
> + #address-cells = <1>;
> + #size-cells = <0>;
> + compatible = "i2c-gpio";
[...]
> +{
> + pinctrl-0 = <_pins>;
> + pinctrl-names = "i2c-hdmi";
> +
> + clock-frequency = <10>;
> +};
[...]
> +{
> + pinctrl-0 = <_pins>;
> + pinctrl-names = "i2c-hdmi";
> +
> + clock-frequency = <10>;
> +};
[...]

It seems that the demux-pinctrl driver reconfigures the pinctrl settings
for the parent devices. I would have expected to have alternative
pinctrl state on the demux node support switching the same external pins
between the different controllers. Wouldn't it be possible to have
pinctrl conflicts between _pins and _pins otherwise?

Regards,
Jan
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Re: [RFC v2 2/4] dt-bindings: i2c: mux: demux-pinctrl: add bindings

2016-01-06 Thread Geert Uytterhoeven 
Hi Wolfram,

On Wed, Jan 6, 2016 at 2:51 PM, Wolfram Sang  wrote:
> These bindings allow an I2C bus to switch between multiple masters. This
> is not hot-swichting because connected I2C slaves will be
> re-instantiated. It is meant to select the best I2C core at runtime once
> the task is known. Example: Prefer i2c-gpio over another I2C core
> because of HW errata affetcing your use case.

> --- /dev/null
> +++ b/Documentation/devicetree/bindings/i2c/i2c-demux-pinctrl.txt
> @@ -0,0 +1,155 @@

> +Here is a snipplet for a bus to be demuxed. It contains various i2c clients 
> for

snippet

> +HDMI, so the bus is named "i2c-hdmi":
> +
> +   i2chdmi: i2c@8 {

Would it make sense to call the node "i2c-bus@8"?
> +
> +   compatible = "i2c-demux-pinctrl";
> +   i2c-parent = <>, <>, <>;

Gr{oetje,eeting}s,

Geert

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[RFC v2 2/4] dt-bindings: i2c: mux: demux-pinctrl: add bindings

2016-01-06 Thread Wolfram Sang 
From: Wolfram Sang 

These bindings allow an I2C bus to switch between multiple masters. This
is not hot-swichting because connected I2C slaves will be
re-instantiated. It is meant to select the best I2C core at runtime once
the task is known. Example: Prefer i2c-gpio over another I2C core
because of HW errata affetcing your use case.

Signed-off-by: Wolfram Sang 
---
 .../devicetree/bindings/i2c/i2c-demux-pinctrl.txt  | 155 +
 1 file changed, 155 insertions(+)
 create mode 100644 Documentation/devicetree/bindings/i2c/i2c-demux-pinctrl.txt

diff --git a/Documentation/devicetree/bindings/i2c/i2c-demux-pinctrl.txt 
b/Documentation/devicetree/bindings/i2c/i2c-demux-pinctrl.txt
new file mode 100644
index 00..de571be68f4754
--- /dev/null
+++ b/Documentation/devicetree/bindings/i2c/i2c-demux-pinctrl.txt
@@ -0,0 +1,155 @@
+Pinctrl-based I2C Bus DeMux
+
+This binding describes an I2C bus demultiplexer that uses pin multiplexing to
+route the I2C signals, and represents the pin multiplexing configuration using
+the pinctrl device tree bindings. This may be used to select one I2C IP core at
+runtime which may have a better feature set for a given task than another I2C
+IP core on the SoC. The most simple example is to fall back to GPIO bitbanging
+if your current runtime configuration hits an errata of the internal IP core.
+
++---+
+| SoC   |
+|   |   +-+  +-+
+|   ++  |   | dev |  | dev |
+|   |I2C IP Core1|--\   |   +-+  +-+
+|   ++   \---+  |  ||
+||Pinctrl|--|--++
+|   ++   +---+  |
+|   |I2C IP Core2|--/   |
+|   ++  |
+|   |
++---+
+
+Required properties:
+- compatible: "i2c-demux-pinctrl"
+- i2c-parent: List of phandles of I2C masters available for selection. The 
first
+ one will be used as default.
+- i2c-bus-name: The name of this bus. Also needed as pinctrl-name for the I2C
+   parents.
+
+Furthermore, I2C mux properties and child nodes. See mux.txt in this directory.
+
+Example:
+
+Here is a snipplet for a bus to be demuxed. It contains various i2c clients for
+HDMI, so the bus is named "i2c-hdmi":
+
+   i2chdmi: i2c@8 {
+
+   compatible = "i2c-demux-pinctrl";
+   i2c-parent = <>, <>, <>;
+   i2c-bus-name = "i2c-hdmi";
+   #address-cells = <1>;
+   #size-cells = <0>;
+
+   ak4643: sound-codec@12 {
+   compatible = "asahi-kasei,ak4643";
+
+   #sound-dai-cells = <0>;
+   reg = <0x12>;
+   };
+
+   composite-in@20 {
+   compatible = "adi,adv7180";
+   reg = <0x20>;
+   remote = <>;
+
+   port {
+   adv7180: endpoint {
+   bus-width = <8>;
+   remote-endpoint = <>;
+   };
+   };
+   };
+
+   hdmi@39 {
+   compatible = "adi,adv7511w";
+   reg = <0x39>;
+   interrupt-parent = <>;
+   interrupts = <15 IRQ_TYPE_LEVEL_LOW>;
+
+   adi,input-depth = <8>;
+   adi,input-colorspace = "rgb";
+   adi,input-clock = "1x";
+   adi,input-style = <1>;
+   adi,input-justification = "evenly";
+
+   ports {
+   #address-cells = <1>;
+   #size-cells = <0>;
+
+   port@0 {
+   reg = <0>;
+   adv7511_in: endpoint {
+   remote-endpoint = 
<_out_lvds0>;
+   };
+   };
+
+   port@1 {
+   reg = <1>;
+   adv7511_out: endpoint {
+   remote-endpoint = <_con>;
+   };
+   };
+   };
+   };
+   };
+
+And for clarification, here are the snipplets for the i2c-parents:
+
+   gpioi2c: i2c@9 {
+   #address-cells = <1>;
+   #size-cells = <0>;
+   compatible = "i2c-gpio";
+   status = "disabled";
+   gpios = < 6 GPIO_ACTIVE_HIGH /*