Re: [PATCH v5 01/14] media: iris: Add iris vpu bus support

[Dmitry Baryshkov]

On Sat, May 09, 2026 at 12:29:50AM +0530, Vishnu Reddy wrote:
> From: Vikash Garodia <vikash.garodia@xxxxxxxxxxxxxxxx>
> 
> On glymur platform, firmware loading needs a separate IOMMU mapping with
> its own stream ID. This stream ID is defined in the device tree with the
> assosiated firmware function ID in the iommu-map property. To create this
> mapping, a separate child device is needed so the firmware memory can be
> isolated in its own IOMMU context.
> 
> Introduced a new bus called iris-vpu-bus. This creates a dynamic device,
> and its dma_configure() callback calls of_dma_configure_id() with the
> function ID provided by the client to map the corresponding stream ID.
> This sets up a dedicated IOMMU context for the child device.
> 
> Reviewed-by: Vishnu Reddy <busanna.reddy@xxxxxxxxxxxxxxxx>
> Signed-off-by: Vikash Garodia <vikash.garodia@xxxxxxxxxxxxxxxx>
> Signed-off-by: Vishnu Reddy <busanna.reddy@xxxxxxxxxxxxxxxx>
> ---
>  drivers/media/platform/qcom/iris/Kconfig        |  4 ++
>  drivers/media/platform/qcom/iris/Makefile       |  1 +
>  drivers/media/platform/qcom/iris/iris_vpu_bus.c | 69 +++++++++++++++++++++++++
>  include/linux/iris_vpu_bus.h                    | 25 +++++++++
>  4 files changed, 99 insertions(+)
> 
> diff --git a/drivers/media/platform/qcom/iris/Kconfig b/drivers/media/platform/qcom/iris/Kconfig
> index 5498f48362d1..025280ef1221 100644
> --- a/drivers/media/platform/qcom/iris/Kconfig
> +++ b/drivers/media/platform/qcom/iris/Kconfig
> @@ -1,3 +1,6 @@
> +config QCOM_IRIS_VPU_BUS
> +        bool
> +
>  config VIDEO_QCOM_IRIS
>          tristate "Qualcomm iris V4L2 decoder driver"
>          depends on VIDEO_DEV
> @@ -6,6 +9,7 @@ config VIDEO_QCOM_IRIS
>          select QCOM_MDT_LOADER
>          select QCOM_SCM
>          select VIDEOBUF2_DMA_CONTIG
> +        select QCOM_IRIS_VPU_BUS
>          help
>            This is a V4L2 driver for Qualcomm iris video accelerator
>            hardware. It accelerates decoding operations on various
> diff --git a/drivers/media/platform/qcom/iris/Makefile b/drivers/media/platform/qcom/iris/Makefile
> index 2abbd3aeb4af..79bc67980339 100644
> --- a/drivers/media/platform/qcom/iris/Makefile
> +++ b/drivers/media/platform/qcom/iris/Makefile
> @@ -31,3 +31,4 @@ qcom-iris-objs += iris_platform_gen1.o
>  endif
>  
>  obj-$(CONFIG_VIDEO_QCOM_IRIS) += qcom-iris.o
> +obj-$(CONFIG_QCOM_IRIS_VPU_BUS) += iris_vpu_bus.o
> diff --git a/drivers/media/platform/qcom/iris/iris_vpu_bus.c b/drivers/media/platform/qcom/iris/iris_vpu_bus.c
> new file mode 100644
> index 000000000000..15ba4d9c563e
> --- /dev/null
> +++ b/drivers/media/platform/qcom/iris/iris_vpu_bus.c
> @@ -0,0 +1,69 @@
> +// SPDX-License-Identifier: GPL-2.0-only
> +/*
> + * Copyright (c) Qualcomm Innovation Center, Inc. All rights reserved.
> + */
> +
> +#include <linux/device.h>
> +#include <linux/iris_vpu_bus.h>
> +#include <linux/of_device.h>
> +
> +static int iris_vpu_bus_dma_configure(struct device *dev)
> +{
> +	const u32 *iommu_fid = dev_get_drvdata(dev);

This should be drm_get_platdata() rather than _drvdata().

> +
> +	return of_dma_configure_id(dev, dev->parent->of_node, true, iommu_fid);
> +}
> +
> +const struct bus_type iris_vpu_bus_type = {
> +	.name = "iris-vpu-bus",
> +	.dma_configure = iris_vpu_bus_dma_configure,
> +};
> +EXPORT_SYMBOL_GPL(iris_vpu_bus_type);
> +
> +static void release_iris_vpu_bus_device(struct device *dev)
> +{
> +	kfree(dev);
> +}
> +
> +struct device *create_iris_vpu_bus_device(struct device *parent_device, const char *name,
> +					  u64 dma_mask, const u32 *iommu_fid)
> +{
> +	struct device *dev;
> +	int ret;
> +
> +	dev = kzalloc_obj(*dev);
> +	if (!dev)
> +		return ERR_PTR(-ENOMEM);
> +
> +	dev->release = release_iris_vpu_bus_device;
> +	dev->bus = &iris_vpu_bus_type;
> +	dev->parent = parent_device;
> +	dev->coherent_dma_mask = dma_mask;
> +	dev->dma_mask = &dev->coherent_dma_mask;
> +
> +	dev_set_name(dev, "%s", name);
> +	dev_set_drvdata(dev, (void *)iommu_fid);
> +
> +	ret = device_register(dev);
> +	if (ret) {
> +		put_device(dev);
> +		return ERR_PTR(ret);
> +	}
> +
> +	return dev;
> +}
> +EXPORT_SYMBOL_GPL(create_iris_vpu_bus_device);
> +
> +static int __init iris_vpu_bus_init(void)
> +{
> +	int ret;
> +
> +	ret = bus_register(&iris_vpu_bus_type);
> +	if (ret) {
> +		pr_err("iris-vpu-bus registration failed: %d\n", ret);

Just 'return bus_register();'

> +		return ret;
> +	}
> +
> +	return 0;
> +}
> +postcore_initcall(iris_vpu_bus_init);
> diff --git a/include/linux/iris_vpu_bus.h b/include/linux/iris_vpu_bus.h
> new file mode 100644
> index 000000000000..7437a2ba411c
> --- /dev/null
> +++ b/include/linux/iris_vpu_bus.h
> @@ -0,0 +1,25 @@
> +/* SPDX-License-Identifier: GPL-2.0-only */
> +/*
> + * Copyright (c) Qualcomm Innovation Center, Inc. All rights reserved.
> + */
> +
> +#ifndef _LINUX_IRIS_VPU_BUS_H
> +#define _LINUX_IRIS_VPU_BUS_H
> +
> +#include <linux/device.h>
> +
> +#ifdef CONFIG_QCOM_IRIS_VPU_BUS
> +extern const struct bus_type iris_vpu_bus_type;
> +
> +struct device *create_iris_vpu_bus_device(struct device *parent_device, const char *name,
> +					  u64 dma_mask, const u32 *iommu_fid);
> +#else
> +static inline struct device *create_iris_vpu_bus_device(struct device *parent_device,

You are adding globally visible API without _any_ sensible prefix. It
should be named other way: iris_vpu_bus_create_device().

> +							const char *name, u64 dma_mask,
> +							const u32 *iommu_fid)
> +{
> +	return ERR_PTR(-ENODEV);
> +}
> +#endif
> +
> +#endif /* _LINUX_IRIS_VPU_BUS_H */
> 
> -- 
> 2.34.1
> 

-- 
With best wishes
Dmitry