by Conor Dooley

[permalink] [raw]

Subject: Re: [PATCH v5 2/4] dt-bindings: media: add Maxim MAX96714 GMSL2 Deserializer

On Wed, Mar 13, 2024 at 10:49:20AM +0100, Julien Massot wrote:
> Add DT bindings for Maxim MAX96714 GMSL2 Deserializer.
>
> Signed-off-by: Julien Massot <[email protected]>
> ---
> Change since v4:
> - Add compatible for MAX96714 and use it as a fallback for MAX96714F
> - Remove extra '|' for decriptions
> - Reference 'i2c-gate' instead of 'i2c-controller'
>
> Change since v3:
> - Renamed file to maxim,max96714.yaml dropped the 'f' suffix
> - Removed mention to C-PHY since it's not supported by MAX96714 deserializers
> - Removed bus-type requirement on CSI endpoint since the device only support D-PHY
> - Removed the clock-lanes property in the dt example
>
> Change since v2:
> - remove reg description
> - rename enable gpio to powerdown
> - use generic node name: i2c, serializer, deserializer
> ---
> .../bindings/media/i2c/maxim,max96714.yaml | 176 ++++++++++++++++++
> 1 file changed, 176 insertions(+)
> create mode 100644 Documentation/devicetree/bindings/media/i2c/maxim,max96714.yaml
>
> diff --git a/Documentation/devicetree/bindings/media/i2c/maxim,max96714.yaml b/Documentation/devicetree/bindings/media/i2c/maxim,max96714.yaml
> new file mode 100644
> index 000000000000..59b116092834
> --- /dev/null
> +++ b/Documentation/devicetree/bindings/media/i2c/maxim,max96714.yaml
> @@ -0,0 +1,176 @@
> +# SPDX-License-Identifier: (GPL-2.0-only OR BSD-2-Clause)
> +# Copyright (C) 2024 Collabora Ltd.
> +%YAML 1.2
> +---
> +$id: http://devicetree.org/schemas/media/i2c/maxim,max96714.yaml#
> +$schema: http://devicetree.org/meta-schemas/core.yaml#
> +
> +title: Maxim MAX96714 GMSL2 to CSI-2 Deserializer
> +
> +maintainers:
> + - Julien Massot <[email protected]>
> +
> +description:
> + The MAX96714 deserializer converts GMSL2 serial inputs into MIPI
> + CSI-2 D-PHY formatted output. The device allows the GMSL2 link to
> + simultaneously transmit bidirectional control-channel data while forward
> + video transmissions are in progress. The MAX96714 can connect to one
> + remotely located serializer using industry-standard coax or STP
> + interconnects. The device cans operate in pixel or tunnel mode. In pixel mode
> + the MAX96714 can select individual video stream, while the tunnel mode forward all
> + the MIPI data received by the serializer.
> +
> + The GMSL2 serial link operates at a fixed rate of 3Gbps or 6Gbps in the
> + forward direction and 187.5Mbps in the reverse direction.
> + MAX96714F only supports a fixed rate of 3Gbps in the forward direction.
> +
> +properties:
> + compatible:
> + oneOf:
> + - enum:
> + - maxim,max96714

There's only once device here, make it const rather than enum.

> + - items:
> + - enum:
> + - maxim,max96714f
> + - const: maxim,max96714 # fallback for 'f' variant

Drop the comment btw, it doesn't make sense given you have an enum that
will allow for more devices and it being a fallback is obvious. That
said, given what you told me on the last version
| Yes there are a few differences visible to the software, for example the
| GMSL
| link rate since MAX96714 support 6 and 3 Gbps, while MAX96714F only
| supports 3Gbps.
| the registers map is the same, but a few values are not possible with
| the 'f' version.
I don't think your ordering here is correct. The 96714 should fall back
to the 96714f, not the opposite that you have here, as the f is the
version which supports fewer features.

I think this should be:

oneOf:
- const: maxim,max96714f
- items:
- enum:
- maxim,max96714
- const: maxim,max96714f

Cheers,
Conor.

> +
> + reg:
> + maxItems: 1
> +
> + powerdown-gpios:
> + maxItems: 1
> + description:
> + Specifier for the GPIO connected to the PWDNB pin.
> +
> + ports:
> + $ref: /schemas/graph.yaml#/properties/ports
> +
> + properties:
> + port@0:
> + $ref: /schemas/graph.yaml#/properties/port
> + unevaluatedProperties: false
> + description: GMSL Input
> + properties:
> + endpoint:
> + $ref: /schemas/media/video-interfaces.yaml#
> + unevaluatedProperties: false
> + description:
> + Endpoint for GMSL2-Link port.
> +
> + port@1:
> + $ref: /schemas/graph.yaml#/$defs/port-base
> + unevaluatedProperties: false
> + description: CSI-2 Output port
> +
> + properties:
> + endpoint:
> + $ref: /schemas/media/video-interfaces.yaml#
> + unevaluatedProperties: false
> +
> + properties:
> + data-lanes:
> + minItems: 1
> + maxItems: 4
> +
> + lane-polarities:
> + minItems: 1
> + maxItems: 5
> +
> + link-frequencies:
> + maxItems: 1
> +
> + required:
> + - data-lanes
> +
> + required:
> + - port@1
> +
> + i2c-gate:
> + $ref: /schemas/i2c/i2c-gate.yaml
> + unevaluatedProperties: false
> + description:
> + The MAX96714 will pass through and forward the I2C requests from the
> + incoming I2C bus over the GMSL2 link. Therefore it supports an i2c-gate
> + subnode to configure a serializer.
> +
> + port0-poc-supply:
> + description: Regulator providing Power over Coax for the GMSL port
> +
> +required:
> + - compatible
> + - reg
> + - ports
> +
> +additionalProperties: false
> +
> +examples:
> + - |
> + #include <dt-bindings/gpio/gpio.h>
> + #include <dt-bindings/media/video-interfaces.h>
> +
> + i2c {
> + #address-cells = <1>;
> + #size-cells = <0>;
> +
> + deserializer@28 {
> + compatible = "maxim,max96714f", "maxim,max96714";
> + reg = <0x28>;
> + powerdown-gpios = <&main_gpio0 37 GPIO_ACTIVE_LOW>;
> +
> + ports {
> + #address-cells = <1>;
> + #size-cells = <0>;
> + port@0 {
> + reg = <0>;
> + max96714_gmsl_in: endpoint {
> + remote-endpoint = <&max96917f_gmsl_out>;
> + };
> + };
> +
> + port@1 {
> + reg = <1>;
> + max96714_csi_out: endpoint {
> + data-lanes = <1 2 3 4>;
> + link-frequencies = /bits/ 64 <400000000>;
> + remote-endpoint = <&csi_in>;
> + };
> + };
> + };
> +
> + i2c-gate {
> + #address-cells = <1>;
> + #size-cells = <0>;
> +
> + serializer@40 {
> + compatible = "maxim,max96717f", "maxim,max96717";
> + reg = <0x40>;
> + gpio-controller;
> + #gpio-cells = <2>;
> + #clock-cells = <0>;
> +
> + ports {
> + #address-cells = <1>;
> + #size-cells = <0>;
> +
> + port@0 {
> + reg = <0>;
> + max96717f_csi_in: endpoint {
> + bus-type = <MEDIA_BUS_TYPE_CSI2_DPHY>;
> + data-lanes = <1 2>;
> + lane-polarities = <1 0 1>;
> + remote-endpoint = <&sensor_out>;
> + };
> + };
> +
> + port@1 {
> + reg = <1>;
> + max96917f_gmsl_out: endpoint {
> + remote-endpoint = <&max96714_gmsl_in>;
> + };
> + };
> + };
> + };
> + };
> + };
> + };
> +...
> --
> 2.44.0
>

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2024-03-25 15:58:13

by Julien Massot

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Subject: Re: [PATCH v5 2/4] dt-bindings: media: add Maxim MAX96714 GMSL2 Deserializer

Hi Conor,

Thanks for your review.
On 3/17/24 16:18, Conor Dooley wrote:
> On Wed, Mar 13, 2024 at 10:49:20AM +0100, Julien Massot wrote:
>> Add DT bindings for Maxim MAX96714 GMSL2 Deserializer.
>>
>> Signed-off-by: Julien Massot <[email protected]>
>> ---
>> Change since v4:
>> - Add compatible for MAX96714 and use it as a fallback for MAX96714F
>> - Remove extra '|' for decriptions
>> - Reference 'i2c-gate' instead of 'i2c-controller'
>>
>> Change since v3:
>> - Renamed file to maxim,max96714.yaml dropped the 'f' suffix
>> - Removed mention to C-PHY since it's not supported by MAX96714 deserializers
>> - Removed bus-type requirement on CSI endpoint since the device only support D-PHY
>> - Removed the clock-lanes property in the dt example
>>
>> Change since v2:
>> - remove reg description
>> - rename enable gpio to powerdown
>> - use generic node name: i2c, serializer, deserializer
>> ---
>> .../bindings/media/i2c/maxim,max96714.yaml | 176 ++++++++++++++++++
>> 1 file changed, 176 insertions(+)
>> create mode 100644 Documentation/devicetree/bindings/media/i2c/maxim,max96714.yaml
>>
>> diff --git a/Documentation/devicetree/bindings/media/i2c/maxim,max96714.yaml b/Documentation/devicetree/bindings/media/i2c/maxim,max96714.yaml
>> new file mode 100644
>> index 000000000000..59b116092834
>> --- /dev/null
>> +++ b/Documentation/devicetree/bindings/media/i2c/maxim,max96714.yaml
>> @@ -0,0 +1,176 @@
>> +# SPDX-License-Identifier: (GPL-2.0-only OR BSD-2-Clause)
>> +# Copyright (C) 2024 Collabora Ltd.
>> +%YAML 1.2
>> +---
>> +$id: http://devicetree.org/schemas/media/i2c/maxim,max96714.yaml#
>> +$schema: http://devicetree.org/meta-schemas/core.yaml#
>> +
>> +title: Maxim MAX96714 GMSL2 to CSI-2 Deserializer
>> +
>> +maintainers:
>> + - Julien Massot <[email protected]>
>> +
>> +description:
>> + The MAX96714 deserializer converts GMSL2 serial inputs into MIPI
>> + CSI-2 D-PHY formatted output. The device allows the GMSL2 link to
>> + simultaneously transmit bidirectional control-channel data while forward
>> + video transmissions are in progress. The MAX96714 can connect to one
>> + remotely located serializer using industry-standard coax or STP
>> + interconnects. The device cans operate in pixel or tunnel mode. In pixel mode
>> + the MAX96714 can select individual video stream, while the tunnel mode forward all
>> + the MIPI data received by the serializer.
>> +
>> + The GMSL2 serial link operates at a fixed rate of 3Gbps or 6Gbps in the
>> + forward direction and 187.5Mbps in the reverse direction.
>> + MAX96714F only supports a fixed rate of 3Gbps in the forward direction.
>> +
>> +properties:
>> + compatible:
>> + oneOf:
>> + - enum:
>> + - maxim,max96714
>
> There's only once device here, make it const rather than enum.

Okay fixed in v6

>
>> + - items:
>> + - enum:
>> + - maxim,max96714f
>> + - const: maxim,max96714 # fallback for 'f' variant
>
> Drop the comment btw, it doesn't make sense given you have an enum that
> will allow for more devices and it being a fallback is obvious. That
> said, given what you told me on the last version
> | Yes there are a few differences visible to the software, for example the
> | GMSL
> | link rate since MAX96714 support 6 and 3 Gbps, while MAX96714F only
> | supports 3Gbps.
> | the registers map is the same, but a few values are not possible with
> | the 'f' version.
> I don't think your ordering here is correct. The 96714 should fall back
> to the 96714f, not the opposite that you have here, as the f is the
> version which supports fewer features.
>
> I think this should be:
>
> oneOf:
> - const: maxim,max96714f
> - items:
> - enum:
> - maxim,max96714
> - const: maxim,max96714f

I just sent a v6 version with your suggestion. Indeed it makes more sense
to use max96714/7f as a fallback for the non f variant.

Best regards,
Julien