Re: [PATCH 1/2] dt-bindings: soc: qcom: Document CDSP Power Management

[Bjorn Andersson]

On Wed, May 20, 2026 at 12:35:09AM +0530, Vignesh Viswanathan wrote:
> Add documentation for the CDSP Power Management driver, which handles

Your commit message should not describe an action, it should describe
the problem you're solving.

> Dynamic Clock and Voltage Scaling (DCVS) requests via SMEM, manages Low
> Power Mode (LPM) transitions via MPM handshake, and provides virtual
> regulators for the remoteproc driver to control CDSP power rails.
> 

You have a node describing the CDSP (remoteproc) already, but it doesn't
contain all the properties, so you're going to add this sibling node.

Why don't you describe the remoteproc properly instead?

> Signed-off-by: Vignesh Viswanathan <vignesh.viswanathan@xxxxxxxxxxxxxxxx>
> ---
>  .../bindings/soc/qcom/qcom,cdsp-power.yaml         | 138 +++++++++++++++++++++
>  1 file changed, 138 insertions(+)
> 
> diff --git a/Documentation/devicetree/bindings/soc/qcom/qcom,cdsp-power.yaml b/Documentation/devicetree/bindings/soc/qcom/qcom,cdsp-power.yaml
> new file mode 100644
> index 000000000000..f0f89fdeba4e
> --- /dev/null
> +++ b/Documentation/devicetree/bindings/soc/qcom/qcom,cdsp-power.yaml
> @@ -0,0 +1,138 @@
> +# SPDX-License-Identifier: GPL-2.0-only OR BSD-2-Clause
> +%YAML 1.2
> +---
> +$id: http://devicetree.org/schemas/soc/qcom/qcom,cdsp-power.yaml#
> +$schema: http://devicetree.org/meta-schemas/core.yaml#
> +
> +title: Qualcomm CDSP Power Management
> +
> +maintainers:
> +  - Vignesh Viswanathan <vignesh.viswanathan@xxxxxxxxxxxxxxxx>
> +
> +description:
> +  The CDSP Power Management driver provides power management services for the
> +  Qualcomm Compute DSP (CDSP) subsystem. It handles Dynamic Clock and Voltage
> +  Scaling (DCVS) requests via SMEM, manages Low Power Mode (LPM) transitions
> +  via MPM handshake, and provides virtual regulators that are consumed by the
> +  CDSP remoteproc driver.
> +
> +properties:
> +  compatible:
> +    const: qcom,cdsp-power
> +
> +  reg:
> +    items:
> +      - description: MPM (Modem Power Manager) register region
> +      - description: RSCC (RSC Configuration) register region
> +
> +  reg-names:
> +    items:
> +      - const: mpm
> +      - const: rscc
> +
> +  interrupts-extended:
> +    items:
> +      - description: LPM (Low Power Mode) interrupt from MPM
> +      - description: DCVS (Dynamic Clock and Voltage Scaling) interrupt from IPCC
> +
> +  interrupt-names:
> +    items:
> +      - const: lpm
> +      - const: dcvs
> +
> +  mboxes:
> +    maxItems: 1
> +    description: IPCC mailbox channel for sending DCVS responses to CDSP
> +
> +  qcom,smem-item:
> +    $ref: /schemas/types.yaml#/definitions/uint32
> +    description:
> +      SMEM item ID used for DCVS communication channel between APSS and CDSP.
> +      This is a platform-specific value that identifies the shared memory region.
> +
> +  vdd-cx-supply:
> +    description:
> +      Phandle to the CX voltage regulator. This is the actual hardware regulator
> +      (e.g., from MP8899 PMIC) that supplies power to the CDSP CX rail.

This isn't the CX supply of the power management block, this is the CX
supply of the remoteproc - so put it there.

> +
> +  vdd-mx-supply:
> +    description:
> +      Phandle to the MX voltage regulator. This is the actual hardware regulator
> +      (e.g., from MP8899 PMIC) that supplies power to the CDSP MX rail. Optional
> +      on boards where MX rail is always-on or not present.
> +
> +  regulators:
> +    type: object
> +    description:
> +      Virtual regulators provided by this driver for consumption by the CDSP
> +      remoteproc driver. These virtual regulators pass through enable/disable
> +      requests to the actual hardware regulators (vdd-cx-supply, vdd-mx-supply).

These regulators doesn't exist in reality, they are only here because
you choose to split the description of your remoteproc implementation in
two.

> +
> +    properties:
> +      cdsp-vdd-cx:
> +        type: object
> +        $ref: /schemas/regulator/regulator.yaml#
> +        description: Virtual CX regulator for CDSP
> +        unevaluatedProperties: false
> +
> +      cdsp-vdd-mx:
> +        type: object
> +        $ref: /schemas/regulator/regulator.yaml#
> +        description: Virtual MX regulator for CDSP
> +        unevaluatedProperties: false
> +
> +    additionalProperties: false
> +
> +required:
> +  - compatible
> +  - reg
> +  - reg-names
> +  - interrupts-extended
> +  - interrupt-names
> +  - mboxes
> +  - qcom,smem-item
> +  - vdd-cx-supply
> +  - regulators
> +
> +additionalProperties: false
> +
> +examples:
> +  - |
> +    #include <dt-bindings/interrupt-controller/arm-gic.h>
> +    #include <dt-bindings/interrupt-controller/irq.h>
> +    #include <dt-bindings/mailbox/qcom-ipcc.h>
> +
> +    soc {
> +        #address-cells = <2>;
> +        #size-cells = <2>;

It's just an example, when you write bindings drop the 0x0 from base and
size in your reg and this need goes away.

> +
> +        cdsp_power: cdsp-power@4ae000 {
> +            compatible = "qcom,cdsp-power";
> +            reg = <0x0 0x004ae000 0x0 0x1000>,

For when you do this properly, please confirm that this is a dedicated
MPM register region and does not alias with any other nodes.

> +                  <0x0 0x26018018 0x0 0x4>;

No, we don't point reg = <> at a single register.

> +            reg-names = "mpm", "rscc";
> +
> +            interrupts-extended = <&intc GIC_SPI 65 IRQ_TYPE_EDGE_RISING 0>,

0?

> +                                  <&ipcc IPCC_CLIENT_CDSP
> +                                         IPCC_MPROC_SIGNAL_PING
> +                                         IRQ_TYPE_EDGE_RISING>;
> +            interrupt-names = "lpm", "dcvs";
> +
> +            mboxes = <&ipcc IPCC_CLIENT_CDSP IPCC_MPROC_SIGNAL_PING>;
> +
> +            qcom,smem-item = <503>;

Isn't this static for the given remoteproc?

Regards,
Bjorn

> +
> +            vdd-cx-supply = <&ipq9650_s2>;
> +            vdd-mx-supply = <&ipq9650_s4>;
> +
> +            regulators {
> +                cdsp_vdd_cx: cdsp-vdd-cx {
> +                    regulator-name = "cdsp-vdd-cx";
> +                };
> +
> +                cdsp_vdd_mx: cdsp-vdd-mx {
> +                    regulator-name = "cdsp-vdd-mx";
> +                };
> +            };
> +        };
> +    };
> 
> -- 
> 2.43.0
>