Re: [PATCH v2 2/3] interconnect: qcom: Add CAMNOC interconnect provider driver

[Krzysztof Kozlowski <krzk@kernel.org>]

On Wed, Aug 19, 2026 at 12:32:10PM +0300, Atanas Filipov wrote:
> Add an ICC provider for the Qualcomm Camera NOC (CAMNOC). Multiple
> camera sub-devices share CAM_CC_CAMNOC_AXI_CLK; direct clk_set_rate()
> calls from each consumer cause a last-writer-wins race.
> 
> Each consumer obtains an ICC path to SLAVE_CAMNOC_AXI and votes via
> icc_set_bw(). The ICC core aggregates votes (max peak_bw) and the
> set() callback converts the result to clk_set_rate(). Consumers
> encode the required frequency as peak_bw in kBps.
> 
> Signed-off-by: Atanas Filipov <atanas.filipov@oss.qualcomm.com>
> ---
>  drivers/interconnect/qcom/Kconfig       |  10 +
>  drivers/interconnect/qcom/Makefile      |   2 +
>  drivers/interconnect/qcom/qcom-camnoc.c | 279 ++++++++++++++++++++++++
>  3 files changed, 291 insertions(+)
>  create mode 100644 drivers/interconnect/qcom/qcom-camnoc.c
> 
> diff --git a/drivers/interconnect/qcom/Kconfig b/drivers/interconnect/qcom/Kconfig
> index 5b8a094ca4ed..9d9d238019a0 100644
> --- a/drivers/interconnect/qcom/Kconfig
> +++ b/drivers/interconnect/qcom/Kconfig
> @@ -135,6 +135,16 @@ config INTERCONNECT_QCOM_NORD
>  	  the RPMh hardware and communicates via Bus Clock Manager (BCM)
>  	  through the Resource State Coordinator (RSC).
>  
> +config INTERCONNECT_QCOM_CAMNOC
> +	tristate "Qualcomm CAMNOC interconnect driver"
> +	depends on INTERCONNECT_QCOM || COMPILE_TEST
> +	depends on ARM64 || COMPILE_TEST

missing default ARCH_QCOM

> +	help
> +	  Say y here to support the Camera Network-on-Chip (CAMNOC)
> +	  interconnect driver for Qualcomm SoCs. It aggregates bandwidth
> +	  requests from camera sub-devices (IFE, JPEG, BPS, etc.) and
> +	  scales CAM_CC_CAMNOC_AXI_CLK accordingly.
> +
>  config INTERCONNECT_QCOM_OSM_L3
>  	tristate "Qualcomm OSM L3 interconnect driver"
>  	depends on INTERCONNECT_QCOM || COMPILE_TEST
> diff --git a/drivers/interconnect/qcom/Makefile b/drivers/interconnect/qcom/Makefile
> index 1c7d410b40cc..52a5998ae6a8 100644
> --- a/drivers/interconnect/qcom/Makefile
> +++ b/drivers/interconnect/qcom/Makefile
> @@ -18,6 +18,7 @@ qnoc-msm8974-objs			:= msm8974.o
>  qnoc-msm8976-objs			:= msm8976.o
>  qnoc-msm8996-objs			:= msm8996.o
>  qnoc-nord-objs				:= nord.o
> +icc-camnoc-objs				:= qcom-camnoc.o
>  icc-osm-l3-objs				:= osm-l3.o
>  qnoc-qcm2290-objs			:= qcm2290.o
>  qnoc-qcs404-objs			:= qcs404.o
> @@ -66,6 +67,7 @@ obj-$(CONFIG_INTERCONNECT_QCOM_MSM8974) += qnoc-msm8974.o
>  obj-$(CONFIG_INTERCONNECT_QCOM_MSM8976) += qnoc-msm8976.o
>  obj-$(CONFIG_INTERCONNECT_QCOM_MSM8996) += qnoc-msm8996.o
>  obj-$(CONFIG_INTERCONNECT_QCOM_NORD) += qnoc-nord.o
> +obj-$(CONFIG_INTERCONNECT_QCOM_CAMNOC) += icc-camnoc.o
>  obj-$(CONFIG_INTERCONNECT_QCOM_OSM_L3) += icc-osm-l3.o
>  obj-$(CONFIG_INTERCONNECT_QCOM_QCM2290) += qnoc-qcm2290.o
>  obj-$(CONFIG_INTERCONNECT_QCOM_QCS404) += qnoc-qcs404.o
> diff --git a/drivers/interconnect/qcom/qcom-camnoc.c b/drivers/interconnect/qcom/qcom-camnoc.c
> new file mode 100644
> index 000000000000..9a703b052b2d
> --- /dev/null
> +++ b/drivers/interconnect/qcom/qcom-camnoc.c
> @@ -0,0 +1,279 @@
> +// SPDX-License-Identifier: GPL-2.0-only
> +/*
> + * Copyright (c) Qualcomm Technologies, Inc. and/or its subsidiaries.
> + *
> + * Qualcomm Camera NOC (CAMNOC) interconnect provider.
> + *
> + * CAMNOC is the internal AXI interconnect within the Qualcomm camera
> + * subsystem. Multiple camera sub-devices (IFE, JPEG, BPS, etc.) share
> + * CAM_CC_CAMNOC_AXI_CLK. This driver acts as an ICC provider so that
> + * each sub-device can independently vote for bandwidth; the ICC core
> + * aggregates the votes (max of peak_bw across all consumers) and this
> + * driver translates the result into a clk_set_rate() call, avoiding
> + * the last-writer-wins race that occurs with direct clk_set_rate().
> + *
> + * Consumers express their required clock rate directly as peak_bw in
> + * kBps (e.g. 400000 for 400 MHz).  The driver converts kBps → Hz:
> + *   rate_hz = peak_bw_kBps * 1000
> + */
> +
> +#include <linux/clk.h>
> +#include <linux/interconnect-provider.h>
> +#include <linux/interconnect.h>
> +#include <linux/module.h>
> +#include <linux/of.h>
> +#include <linux/platform_device.h>
> +
> +#include <dt-bindings/interconnect/qcom,camnoc.h>
> +
> +#define to_camnoc_provider(_p) \
> +	container_of(_p, struct qcom_camnoc_icc_provider, provider)
> +
> +struct qcom_camnoc_icc_provider {
> +	struct clk *clk;
> +	struct icc_provider provider;
> +};
> +
> +struct qcom_camnoc_node {
> +	const char *name;
> +	u16 buswidth;
> +};
> +
> +/* IFE */
> +static const struct qcom_camnoc_node camnoc_master_ife_0 = {
> +	.name = "master-camnoc-ife-0", .buswidth = 16
> +};
> +
> +static const struct qcom_camnoc_node camnoc_master_ife_0_rdi = {
> +	.name = "master-camnoc-ife-0-rdi", .buswidth = 16
> +};
> +
> +static const struct qcom_camnoc_node camnoc_master_ife_1 = {
> +	.name = "master-camnoc-ife-1", .buswidth = 16
> +};
> +
> +static const struct qcom_camnoc_node camnoc_master_ife_1_rdi = {
> +	.name = "master-camnoc-ife-1-rdi", .buswidth = 16
> +};
> +
> +static const struct qcom_camnoc_node camnoc_master_ife_lite_0 = {
> +	.name = "master-camnoc-ife-lite-0", .buswidth = 8
> +};
> +
> +static const struct qcom_camnoc_node camnoc_master_ife_lite_1 = {
> +	.name = "master-camnoc-ife-lite-1", .buswidth = 8
> +};
> +
> +static const struct qcom_camnoc_node camnoc_master_ife_lite_2 = {
> +	.name = "master-camnoc-ife-lite-2", .buswidth = 8
> +};
> +
> +static const struct qcom_camnoc_node camnoc_master_ife_lite_3 = {
> +	.name = "master-camnoc-ife-lite-3", .buswidth = 8
> +};
> +
> +static const struct qcom_camnoc_node camnoc_master_ife_lite_4 = {
> +	.name = "master-camnoc-ife-lite-4", .buswidth = 8
> +};
> +
> +/* BPS */
> +static const struct qcom_camnoc_node camnoc_master_bps = {
> +	.name = "master-camnoc-bps", .buswidth = 16
> +};
> +
> +/* IPE */
> +static const struct qcom_camnoc_node camnoc_master_ipe_0 = {
> +	.name = "master-camnoc-ipe-0", .buswidth = 16
> +};
> +
> +static const struct qcom_camnoc_node camnoc_master_ipe_1 = {
> +	.name = "master-camnoc-ipe-1", .buswidth = 16
> +};
> +
> +/* JPEG */
> +static const struct qcom_camnoc_node camnoc_master_jpeg = {
> +	.name = "master-camnoc-jpeg", .buswidth = 16
> +};
> +
> +static const struct qcom_camnoc_node camnoc_master_jpeg_dma = {
> +	.name = "master-camnoc-jpeg-dma", .buswidth = 16
> +};
> +
> +/* CDM */
> +static const struct qcom_camnoc_node camnoc_master_cdm = {
> +	.name = "master-camnoc-cdm", .buswidth = 4
> +};
> +
> +/* FD */
> +static const struct qcom_camnoc_node camnoc_master_fd = {
> +	.name = "master-camnoc-fd", .buswidth = 16
> +};
> +
> +/* SBI */
> +static const struct qcom_camnoc_node camnoc_master_sbi = {
> +	.name = "master-camnoc-sbi", .buswidth = 16
> +};
> +
> +/* ICP */
> +static const struct qcom_camnoc_node camnoc_master_icp = {
> +	.name = "master-camnoc-icp", .buswidth = 8
> +};
> +
> +/* Slave */
> +static const struct qcom_camnoc_node camnoc_slave_axi = {
> +	.name = "slave-camnoc-axi", .buswidth = 32
> +};
> +
> +static const struct qcom_camnoc_node * const camnoc_nodes[] = {
> +	[MASTER_CAMNOC_IFE_0]      = &camnoc_master_ife_0,
> +	[MASTER_CAMNOC_IFE_0_RDI]  = &camnoc_master_ife_0_rdi,
> +	[MASTER_CAMNOC_IFE_1]      = &camnoc_master_ife_1,
> +	[MASTER_CAMNOC_IFE_1_RDI]  = &camnoc_master_ife_1_rdi,
> +	[MASTER_CAMNOC_IFE_LITE_0] = &camnoc_master_ife_lite_0,
> +	[MASTER_CAMNOC_IFE_LITE_1] = &camnoc_master_ife_lite_1,
> +	[MASTER_CAMNOC_IFE_LITE_2] = &camnoc_master_ife_lite_2,
> +	[MASTER_CAMNOC_IFE_LITE_3] = &camnoc_master_ife_lite_3,
> +	[MASTER_CAMNOC_IFE_LITE_4] = &camnoc_master_ife_lite_4,
> +	[MASTER_CAMNOC_BPS]        = &camnoc_master_bps,
> +	[MASTER_CAMNOC_IPE_0]      = &camnoc_master_ipe_0,
> +	[MASTER_CAMNOC_IPE_1]      = &camnoc_master_ipe_1,
> +	[MASTER_CAMNOC_JPEG]       = &camnoc_master_jpeg,
> +	[MASTER_CAMNOC_JPEG_DMA]   = &camnoc_master_jpeg_dma,
> +	[MASTER_CAMNOC_CDM]        = &camnoc_master_cdm,
> +	[MASTER_CAMNOC_FD]         = &camnoc_master_fd,
> +	[MASTER_CAMNOC_SBI]        = &camnoc_master_sbi,
> +	[MASTER_CAMNOC_ICP]        = &camnoc_master_icp,
> +	[SLAVE_CAMNOC_AXI]         = &camnoc_slave_axi,
> +};
> +
> +#define CAMNOC_NUM_NODES	ARRAY_SIZE(camnoc_nodes)
> +
> +static int qcom_camnoc_get_bw(struct icc_node *node, u32 *avg, u32 *peak)
> +{
> +	*avg = 0;
> +	*peak = 0;
> +
> +	return 0;
> +}
> +
> +static int qcom_camnoc_set(struct icc_node *src, struct icc_node *dst)
> +{
> +	struct qcom_camnoc_icc_provider *cp =
> +		to_camnoc_provider(src->provider);
> +	unsigned long rate;
> +
> +	/*
> +	 * peak_bw is the aggregated max across all consumers (kBps).
> +	 * Consumers encode the required clock frequency directly as kBps,
> +	 * so the conversion is simply: rate_hz = peak_bw * 1000.
> +	 * A vote of 0 means no requirement; leave the clock at its minimum.
> +	 */
> +	rate = icc_units_to_bps(dst->peak_bw);
> +
> +	return clk_set_rate(cp->clk, rate);

This driver does nothing to the ICC hardware, no votes. It only
translates kbps to Hz. This is not the purpose of ICC drivers.

Looks heavily incomplete.

Best regards,
Krzysztof