diff mbox series

[RESEND,3/4] dt-bindings: drm/bridge: Add GPIO display mux binding

Message ID 20191211061911.238393-4-hsinyi@chromium.org (mailing list archive)
State New, archived
Headers show
Series drm: bridge: anx7688 and mux drivers | expand

Commit Message

Hsin-Yi Wang Dec. 11, 2019, 6:19 a.m. UTC 
From: Nicolas Boichat <drinkcat@chromium.org>

Add bindings for Generic GPIO mux driver.

Signed-off-by: Nicolas Boichat <drinkcat@chromium.org>
Signed-off-by: Hsin-Yi Wang <hsinyi@chromium.org>
---
Change from RFC to v1:
- txt to yaml
---
 .../bindings/display/bridge/gpio-mux.yaml     | 89 +++++++++++++++++++
 1 file changed, 89 insertions(+)
 create mode 100644 Documentation/devicetree/bindings/display/bridge/gpio-mux.yaml

Comments

Rob Herring Dec. 13, 2019, 1:53 p.m. UTC | #1 
On Wed, Dec 11, 2019 at 12:19 AM Hsin-Yi Wang <hsinyi@chromium.org> wrote:
>
> From: Nicolas Boichat <drinkcat@chromium.org>
>
> Add bindings for Generic GPIO mux driver.
>
> Signed-off-by: Nicolas Boichat <drinkcat@chromium.org>
> Signed-off-by: Hsin-Yi Wang <hsinyi@chromium.org>
> ---
> Change from RFC to v1:
> - txt to yaml
> ---
>  .../bindings/display/bridge/gpio-mux.yaml     | 89 +++++++++++++++++++
>  1 file changed, 89 insertions(+)
>  create mode 100644 Documentation/devicetree/bindings/display/bridge/gpio-mux.yaml
>
> diff --git a/Documentation/devicetree/bindings/display/bridge/gpio-mux.yaml b/Documentation/devicetree/bindings/display/bridge/gpio-mux.yaml
> new file mode 100644
> index 000000000000..cef098749066
> --- /dev/null
> +++ b/Documentation/devicetree/bindings/display/bridge/gpio-mux.yaml
> @@ -0,0 +1,89 @@
> +# SPDX-License-Identifier: GPL-2.0
> +%YAML 1.2
> +---
> +$id: http://devicetree.org/schemas/display/bridge/gpio-mux.yaml#
> +$schema: http://devicetree.org/meta-schemas/core.yaml#
> +
> +title: Generic display mux (1 input, 2 outputs)

What makes it generic? Doesn't the mux chip have power supply,
possibly a reset line or not, etc.? What about a mux where the GPIO
controls the mux?

Generally, we avoid 'generic' bindings because h/w is rarely generic.
You can have a generic driver which works on multiple devices.

> +
> +maintainers:
> +  - Nicolas Boichat <drinkcat@chromium.org>
> +
> +description: |
> +  This bindings describes a simple display (e.g. HDMI) mux, that has 1
> +  input, and 2 outputs. The mux status is controlled by hardware, and
> +  its status is read back using a GPIO.
> +
> +properties:
> +  compatible:
> +    const: gpio-display-mux
> +
> +  detect-gpios:
> +    maxItems: 1
> +    description: GPIO that indicates the active output
> +
> +  ports:
> +    type: object
> +
> +    properties:
> +      port@0:
> +        type: object
> +        description: |
> +          Video port for input.
> +
> +      port@1:
> +        type: object
> +        description: |
> +          2 video ports for output.
> +          The reg value in the endpoints matches the GPIO status: when
> +          GPIO is asserted, endpoint with reg value <1> is selected.

You should describe 'endpoint@0' and 'endpoint@1' here too.

> +
> +    required:
> +      - port@0
> +      - port@1
> +
> +required:
> +  - compatible
> +  - detect-gpios
> +  - ports
> +
> +examples:
> +  - |
> +    hdmi_mux: hdmi_mux {
> +      compatible = "gpio-display-mux";
> +      status = "okay";

Don't show status in examples.

> +      detect-gpios = <&pio 36 GPIO_ACTIVE_HIGH>;
> +      pinctrl-names = "default";
> +      pinctrl-0 = <&hdmi_mux_pins>;
> +      ddc-i2c-bus = <&hdmiddc0>;

Not documented. Is the i2c bus muxed too? If not, then this is in the
wrong place.

> +
> +      ports {
> +        #address-cells = <1>;
> +        #size-cells = <0>;
> +
> +        port@0 { /* input */
> +          reg = <0>;
> +
> +          hdmi_mux_in: endpoint {
> +            remote-endpoint = <&hdmi0_out>;
> +          };
> +        };
> +
> +        port@1 { /* output */
> +          reg = <1>;
> +
> +          #address-cells = <1>;
> +          #size-cells = <0>;
> +
> +          hdmi_mux_out_anx: endpoint@0 {
> +            reg = <0>;
> +            remote-endpoint = <&anx7688_in>;
> +          };
> +
> +          hdmi_mux_out_hdmi: endpoint@1 {
> +            reg = <1>;
> +            remote-endpoint = <&hdmi_connector_in>;
> +          };
> +        };
> +      };
> +    };
> --
> 2.24.0.525.g8f36a354ae-goog
>
Hsin-Yi Wang Dec. 16, 2019, 7:16 a.m. UTC | #2 
On Sat, Dec 14, 2019 at 5:29 AM Rob Herring <robh+dt@kernel.org> wrote:
>
> On Wed, Dec 11, 2019 at 12:19 AM Hsin-Yi Wang <hsinyi@chromium.org> wrote:
> >
> > From: Nicolas Boichat <drinkcat@chromium.org>
> >
> > Add bindings for Generic GPIO mux driver.
> >
> > Signed-off-by: Nicolas Boichat <drinkcat@chromium.org>
> > Signed-off-by: Hsin-Yi Wang <hsinyi@chromium.org>
> > ---
> > Change from RFC to v1:
> > - txt to yaml
> > ---
> >  .../bindings/display/bridge/gpio-mux.yaml     | 89 +++++++++++++++++++
> >  1 file changed, 89 insertions(+)
> >  create mode 100644 Documentation/devicetree/bindings/display/bridge/gpio-mux.yaml
> >
> > diff --git a/Documentation/devicetree/bindings/display/bridge/gpio-mux.yaml b/Documentation/devicetree/bindings/display/bridge/gpio-mux.yaml
> > new file mode 100644
> > index 000000000000..cef098749066
> > --- /dev/null
> > +++ b/Documentation/devicetree/bindings/display/bridge/gpio-mux.yaml
> > @@ -0,0 +1,89 @@
> > +# SPDX-License-Identifier: GPL-2.0
> > +%YAML 1.2
> > +---
> > +$id: http://devicetree.org/schemas/display/bridge/gpio-mux.yaml#
> > +$schema: http://devicetree.org/meta-schemas/core.yaml#
> > +
> > +title: Generic display mux (1 input, 2 outputs)
>
> What makes it generic? Doesn't the mux chip have power supply,
> possibly a reset line or not, etc.? What about a mux where the GPIO
> controls the mux?
>
> Generally, we avoid 'generic' bindings because h/w is rarely generic.
> You can have a generic driver which works on multiple devices.
>
Then how about making it mt8173-oak-gpio-mux? Since this is currently
only used in this board.

> > +
> > +maintainers:
> > +  - Nicolas Boichat <drinkcat@chromium.org>
> > +
> > +description: |
> > +  This bindings describes a simple display (e.g. HDMI) mux, that has 1
> > +  input, and 2 outputs. The mux status is controlled by hardware, and
> > +  its status is read back using a GPIO.
> > +
> > +properties:
> > +  compatible:
> > +    const: gpio-display-mux
> > +
> > +  detect-gpios:
> > +    maxItems: 1
> > +    description: GPIO that indicates the active output
> > +
> > +  ports:
> > +    type: object
> > +
> > +    properties:
> > +      port@0:
> > +        type: object
> > +        description: |
> > +          Video port for input.
> > +
> > +      port@1:
> > +        type: object
> > +        description: |
> > +          2 video ports for output.
> > +          The reg value in the endpoints matches the GPIO status: when
> > +          GPIO is asserted, endpoint with reg value <1> is selected.
>
> You should describe 'endpoint@0' and 'endpoint@1' here too.
Will add in next version, thanks
>
> > +
> > +    required:
> > +      - port@0
> > +      - port@1
> > +
> > +required:
> > +  - compatible
> > +  - detect-gpios
> > +  - ports
> > +
> > +examples:
> > +  - |
> > +    hdmi_mux: hdmi_mux {
> > +      compatible = "gpio-display-mux";
> > +      status = "okay";
>
> Don't show status in examples.
>
> > +      detect-gpios = <&pio 36 GPIO_ACTIVE_HIGH>;
> > +      pinctrl-names = "default";
> > +      pinctrl-0 = <&hdmi_mux_pins>;
> > +      ddc-i2c-bus = <&hdmiddc0>;
>
> Not documented. Is the i2c bus muxed too? If not, then this is in the
> wrong place.
>
It's muxed, but this is required because of [1], so it should be
removed in this example.

[1]https://elixir.bootlin.com/linux/v5.5-rc2/source/Documentation/devicetree/bindings/display/mediatek/mediatek,hdmi.txt#L24
> > +
> > +      ports {
> > +        #address-cells = <1>;
> > +        #size-cells = <0>;
> > +
> > +        port@0 { /* input */
> > +          reg = <0>;
> > +
> > +          hdmi_mux_in: endpoint {
> > +            remote-endpoint = <&hdmi0_out>;
> > +          };
> > +        };
> > +
> > +        port@1 { /* output */
> > +          reg = <1>;
> > +
> > +          #address-cells = <1>;
> > +          #size-cells = <0>;
> > +
> > +          hdmi_mux_out_anx: endpoint@0 {
> > +            reg = <0>;
> > +            remote-endpoint = <&anx7688_in>;
> > +          };
> > +
> > +          hdmi_mux_out_hdmi: endpoint@1 {
> > +            reg = <1>;
> > +            remote-endpoint = <&hdmi_connector_in>;
> > +          };
> > +        };
> > +      };
> > +    };
> > --
> > 2.24.0.525.g8f36a354ae-goog
> >
Rob Herring Dec. 19, 2019, 8:48 p.m. UTC | #3 
On Mon, Dec 16, 2019 at 03:16:23PM +0800, Hsin-Yi Wang wrote:
> On Sat, Dec 14, 2019 at 5:29 AM Rob Herring <robh+dt@kernel.org> wrote:
> >
> > On Wed, Dec 11, 2019 at 12:19 AM Hsin-Yi Wang <hsinyi@chromium.org> wrote:
> > >
> > > From: Nicolas Boichat <drinkcat@chromium.org>
> > >
> > > Add bindings for Generic GPIO mux driver.
> > >
> > > Signed-off-by: Nicolas Boichat <drinkcat@chromium.org>
> > > Signed-off-by: Hsin-Yi Wang <hsinyi@chromium.org>
> > > ---
> > > Change from RFC to v1:
> > > - txt to yaml
> > > ---
> > >  .../bindings/display/bridge/gpio-mux.yaml     | 89 +++++++++++++++++++
> > >  1 file changed, 89 insertions(+)
> > >  create mode 100644 Documentation/devicetree/bindings/display/bridge/gpio-mux.yaml
> > >
> > > diff --git a/Documentation/devicetree/bindings/display/bridge/gpio-mux.yaml b/Documentation/devicetree/bindings/display/bridge/gpio-mux.yaml
> > > new file mode 100644
> > > index 000000000000..cef098749066
> > > --- /dev/null
> > > +++ b/Documentation/devicetree/bindings/display/bridge/gpio-mux.yaml
> > > @@ -0,0 +1,89 @@
> > > +# SPDX-License-Identifier: GPL-2.0
> > > +%YAML 1.2
> > > +---
> > > +$id: http://devicetree.org/schemas/display/bridge/gpio-mux.yaml#
> > > +$schema: http://devicetree.org/meta-schemas/core.yaml#
> > > +
> > > +title: Generic display mux (1 input, 2 outputs)
> >
> > What makes it generic? Doesn't the mux chip have power supply,
> > possibly a reset line or not, etc.? What about a mux where the GPIO
> > controls the mux?
> >
> > Generally, we avoid 'generic' bindings because h/w is rarely generic.
> > You can have a generic driver which works on multiple devices.
> >
> Then how about making it mt8173-oak-gpio-mux? Since this is currently
> only used in this board.

Isn't there an underlying part# you can use? Or if you can point me to 
multiple chips implementing the same thing, then maybe a generic binding 
is fine.

Rob
Hsin-Yi Wang Dec. 20, 2019, 3:57 a.m. UTC | #4 
On Fri, Dec 20, 2019 at 4:48 AM Rob Herring <robh@kernel.org> wrote:
>
> On Mon, Dec 16, 2019 at 03:16:23PM +0800, Hsin-Yi Wang wrote:
> > On Sat, Dec 14, 2019 at 5:29 AM Rob Herring <robh+dt@kernel.org> wrote:
> > >
> > > On Wed, Dec 11, 2019 at 12:19 AM Hsin-Yi Wang <hsinyi@chromium.org> wrote:
> > > >
> > > > From: Nicolas Boichat <drinkcat@chromium.org>
> > > >
> > > > Add bindings for Generic GPIO mux driver.
> > > >
> > > > Signed-off-by: Nicolas Boichat <drinkcat@chromium.org>
> > > > Signed-off-by: Hsin-Yi Wang <hsinyi@chromium.org>
> > > > ---
> > > > Change from RFC to v1:
> > > > - txt to yaml
> > > > ---
> > > >  .../bindings/display/bridge/gpio-mux.yaml     | 89 +++++++++++++++++++
> > > >  1 file changed, 89 insertions(+)
> > > >  create mode 100644 Documentation/devicetree/bindings/display/bridge/gpio-mux.yaml
> > > >
> > > > diff --git a/Documentation/devicetree/bindings/display/bridge/gpio-mux.yaml b/Documentation/devicetree/bindings/display/bridge/gpio-mux.yaml
> > > > new file mode 100644
> > > > index 000000000000..cef098749066
> > > > --- /dev/null
> > > > +++ b/Documentation/devicetree/bindings/display/bridge/gpio-mux.yaml
> > > > @@ -0,0 +1,89 @@
> > > > +# SPDX-License-Identifier: GPL-2.0
> > > > +%YAML 1.2
> > > > +---
> > > > +$id: http://devicetree.org/schemas/display/bridge/gpio-mux.yaml#
> > > > +$schema: http://devicetree.org/meta-schemas/core.yaml#
> > > > +
> > > > +title: Generic display mux (1 input, 2 outputs)
> > >
> > > What makes it generic? Doesn't the mux chip have power supply,
> > > possibly a reset line or not, etc.? What about a mux where the GPIO
> > > controls the mux?
> > >
> > > Generally, we avoid 'generic' bindings because h/w is rarely generic.
> > > You can have a generic driver which works on multiple devices.
> > >
> > Then how about making it mt8173-oak-gpio-mux? Since this is currently
> > only used in this board.
>
> Isn't there an underlying part# you can use? Or if you can point me to
> multiple chips implementing the same thing, then maybe a generic binding
> is fine.
There are some similar chips, for example:
https://www.paradetech.com/zh-hant/%E7%94%A2%E5%93%81%E4%BB%8B%E7%B4%B9/ps8223-3-0gbps-hdmi-12-demultiplexer/
and http://www.ti.com/lit/ds/symlink/ts3dv642.pdf
If they are used in a similar way
(https://lore.kernel.org/lkml/CANMq1KDDEzPWhByEtn-EjNcg+ofVT2MW-hOXANGooYFOYJ35VA@mail.gmail.com/),
they would need such driver. But currently we only know that mt8173
oak board have this use case.
>
> Rob
diff mbox series

Patch

diff --git a/Documentation/devicetree/bindings/display/bridge/gpio-mux.yaml b/Documentation/devicetree/bindings/display/bridge/gpio-mux.yaml
new file mode 100644
index 000000000000..cef098749066
--- /dev/null
+++ b/Documentation/devicetree/bindings/display/bridge/gpio-mux.yaml
@@ -0,0 +1,89 @@ 
+# SPDX-License-Identifier: GPL-2.0
+%YAML 1.2
+---
+$id: http://devicetree.org/schemas/display/bridge/gpio-mux.yaml#
+$schema: http://devicetree.org/meta-schemas/core.yaml#
+
+title: Generic display mux (1 input, 2 outputs)
+
+maintainers:
+  - Nicolas Boichat <drinkcat@chromium.org>
+
+description: |
+  This bindings describes a simple display (e.g. HDMI) mux, that has 1
+  input, and 2 outputs. The mux status is controlled by hardware, and
+  its status is read back using a GPIO.
+
+properties:
+  compatible:
+    const: gpio-display-mux
+
+  detect-gpios:
+    maxItems: 1
+    description: GPIO that indicates the active output
+
+  ports:
+    type: object
+
+    properties:
+      port@0:
+        type: object
+        description: |
+          Video port for input.
+
+      port@1:
+        type: object
+        description: |
+          2 video ports for output.
+          The reg value in the endpoints matches the GPIO status: when
+          GPIO is asserted, endpoint with reg value <1> is selected.
+
+    required:
+      - port@0
+      - port@1
+
+required:
+  - compatible
+  - detect-gpios
+  - ports
+
+examples:
+  - |
+    hdmi_mux: hdmi_mux {
+      compatible = "gpio-display-mux";
+      status = "okay";
+      detect-gpios = <&pio 36 GPIO_ACTIVE_HIGH>;
+      pinctrl-names = "default";
+      pinctrl-0 = <&hdmi_mux_pins>;
+      ddc-i2c-bus = <&hdmiddc0>;
+
+      ports {
+        #address-cells = <1>;
+        #size-cells = <0>;
+
+        port@0 { /* input */
+          reg = <0>;
+
+          hdmi_mux_in: endpoint {
+            remote-endpoint = <&hdmi0_out>;
+          };
+        };
+
+        port@1 { /* output */
+          reg = <1>;
+
+          #address-cells = <1>;
+          #size-cells = <0>;
+
+          hdmi_mux_out_anx: endpoint@0 {
+            reg = <0>;
+            remote-endpoint = <&anx7688_in>;
+          };
+
+          hdmi_mux_out_hdmi: endpoint@1 {
+            reg = <1>;
+            remote-endpoint = <&hdmi_connector_in>;
+          };
+        };
+      };
+    };