Re: [PATCH v1 1/3] dt-bindings: interconnect: Add Qualcomm CAMNOC ICC binding

[Atanas Filipov <atanas.filipov@oss.qualcomm.com>]

On 8/8/2026 12:12 AM, Dmitry Baryshkov wrote:
> On Fri, Aug 07, 2026 at 02:49:49PM +0300, Atanas Filipov wrote:
>> Add a device tree binding for the Qualcomm Camera Network-on-Chip
>> (CAMNOC) interconnect provider. CAMNOC is the internal AXI
>> interconnect within the camera subsystem that arbitrates bandwidth
>> between camera sub-devices and the external memory interconnect.
>>
>> The CAMNOC ICC provider aggregates bandwidth requests from multiple
>> independent consumers and scales the CAMNOC AXI clock accordingly,
>> avoiding the race conditions that arise when each consumer calls
>> clk_set_rate() directly on the shared clock.
>>
>> Signed-off-by: Atanas Filipov <atanas.filipov@oss.qualcomm.com>
>> ---
>>   .../bindings/interconnect/qcom,camnoc.yaml    | 98 +++++++++++++++++++
>>   .../dt-bindings/interconnect/qcom,camnoc.h    | 12 +++
>>   2 files changed, 110 insertions(+)
>>   create mode 100644 Documentation/devicetree/bindings/interconnect/qcom,camnoc.yaml
>>   create mode 100644 include/dt-bindings/interconnect/qcom,camnoc.h
>>
>> diff --git a/Documentation/devicetree/bindings/interconnect/qcom,camnoc.yaml b/Documentation/devicetree/bindings/interconnect/qcom,camnoc.yaml
>> new file mode 100644
>> index 000000000000..b2f5c140ff80
>> --- /dev/null
>> +++ b/Documentation/devicetree/bindings/interconnect/qcom,camnoc.yaml
>> @@ -0,0 +1,98 @@
>> +# SPDX-License-Identifier: (GPL-2.0-only OR BSD-2-Clause)
>> +%YAML 1.2
>> +---
>> +$id: http://devicetree.org/schemas/interconnect/qcom,camnoc.yaml#
>> +$schema: http://devicetree.org/meta-schemas/core.yaml#
>> +
>> +title: Qualcomm Camera NOC (CAMNOC) Interconnect Provider
>> +
>> +maintainers:
>> +  - Aleksandar Filipov <quic_afilipov@quicinc.com>
>> +
>> +description:
>> +  The Camera Network-on-Chip (CAMNOC) is the internal AXI interconnect
>> +  within the Qualcomm camera subsystem. It arbitrates AXI bandwidth
>> +  between camera sub-devices (IFE, JPEG, BPS, etc.) and the external
>> +  memory interconnect. Multiple consumers may independently request
>> +  bandwidth; the CAMNOC ICC provider aggregates these requests and
>> +  scales CAM_CC_CAMNOC_AXI_CLK accordingly.
>> +
>> +properties:
>> +  compatible:
>> +    enum:
>> +      - qcom,sm8250-cam-virt
>> +
>> +  clocks:
>> +    items:
>> +      - description: CAMNOC AXI clock
>> +
>> +  clock-names:
>> +    items:
>> +      - const: camnoc_axi
>> +
>> +  '#interconnect-cells':
>> +    const: 1
>> +
>> +required:
>> +  - compatible
>> +  - clocks
>> +  - clock-names
>> +  - '#interconnect-cells'
>> +
>> +additionalProperties: false
>> +
>> +examples:
>> +  - |
>> +    #include <dt-bindings/clock/qcom,camcc-sm8250.h>
>> +    #include <dt-bindings/interconnect/qcom,camnoc.h>
>> +
>> +    camnoc_icc: interconnect {
>> +        compatible = "qcom,sm8250-cam-virt";
>> +        clocks = <&camcc CAM_CC_CAMNOC_AXI_CLK>;
>> +        clock-names = "camnoc_axi";
>> +        #interconnect-cells = <1>;
>> +    };
>> +
>> +    /* Example camera sub-device consuming the CAMNOC provider above */
>> +    camera-subsystem@ac53000 {
>> +        reg = <0x0ac53000 0x1000>;
>> +
>> +        interconnects = <&camnoc_icc MASTER_CAMNOC_JPEG
>> +                         &camnoc_icc SLAVE_CAMNOC_AXI>;
>> +        interconnect-names = "camnoc";
>> +
>> +        /*
>> +         * Optional: an operating-points-v2 table lets the consumer
>> +         * drive its CAMNOC bandwidth vote from the same OPP that
>> +         * selects its core clock rate and RPMh performance state.
> 
> Is this a table for the camera-subsystem or for the CAMNOC_AXI_CLK? In
> the latter case, the OPP table should be a part of the camnoc device.
> 

The OPP table in the example belongs to the consumer device, not to the 
CAMNOC provider. It describes the operating points
of the camera sub-device itself: core clock frequency, RPMh performance 
state, and CAMNOC bandwidth vote bundled together in
a single OPP entry. The opp-peak-kBps field is the bandwidth the 
consumer passes to icc_set_bw() when it transitions to that
operating point.

This follows the standard ICC consumer pattern: the consumer owns the 
OPP table and uses opp-peak-kBps to drive its bandwidth
vote. The CAMNOC provider has no per-consumer bandwidth table of its own 
— it only aggregates the votes it receives.

The comment in the example was perhaps misleading. I will reword it in 
v2 to make it clear that the OPP table belongs to the
consumer and that opp-peak-kBps is the ICC bandwidth vote, not a clock 
rate table for CAMNOC_AXI_CLK.

>> +         */
>> +        operating-points-v2 = <&camera_opp_table>;
>> +
>> +        camera_opp_table: opp-table {
>> +            compatible = "operating-points-v2";
>> +
>> +            opp-100000000 {
>> +                opp-hz = /bits/ 64 <100000000>;
>> +                opp-peak-kBps = <22246>;
>> +                required-opps = <&rpmhpd_opp_min_svs>;
>> +            };
>> +
>> +            opp-200000000 {
>> +                opp-hz = /bits/ 64 <200000000>;
>> +                opp-peak-kBps = <44492>;
>> +                required-opps = <&rpmhpd_opp_low_svs>;
>> +            };
>> +
>> +            opp-400000000 {
>> +                opp-hz = /bits/ 64 <400000000>;
>> +                opp-peak-kBps = <88983>;
>> +                required-opps = <&rpmhpd_opp_svs>;
>> +            };
>> +
>> +            opp-480000000 {
>> +                opp-hz = /bits/ 64 <480000000>;
>> +                opp-peak-kBps = <106780>;
>> +                required-opps = <&rpmhpd_opp_svs_l1>;
>> +            };
>> +        };
>> +    };
>> diff --git a/include/dt-bindings/interconnect/qcom,camnoc.h b/include/dt-bindings/interconnect/qcom,camnoc.h
>> new file mode 100644
>> index 000000000000..a03f5e3f6446
>> --- /dev/null
>> +++ b/include/dt-bindings/interconnect/qcom,camnoc.h
>> @@ -0,0 +1,12 @@
>> +/* SPDX-License-Identifier: GPL-2.0-only OR BSD-2-Clause */
>> +/*
>> + * Copyright (c) Qualcomm Technologies, Inc. and/or its subsidiaries.
>> + */
>> +
>> +#ifndef __DT_BINDINGS_INTERCONNECT_QCOM_CAMNOC_H
>> +#define __DT_BINDINGS_INTERCONNECT_QCOM_CAMNOC_H
>> +
>> +#define MASTER_CAMNOC_JPEG	0
> 
> I guess, there are other connection ports. Please describe them.
> 
>> +#define SLAVE_CAMNOC_AXI	1
>> +
>> +#endif /* __DT_BINDINGS_INTERCONNECT_QCOM_CAMNOC_H */
>> -- 
>> 2.34.1
>>
>