Re: [PATCH v2 1/8] media: platform: amd: Introduce amd isp4 capture driver

Mario Limonciello
2025-06-19T13:00:50Z

On 6/19/2025 2:46 AM, Du, Bin wrote:
> Many thx Mario for your comments, really helpful, will address all of
> them in the next patch.
> Add inline for some of your comments, pls check
>
> On 6/18/2025 11:58 PM, Mario Limonciello wrote:
>> On 6/18/2025 4:19 AM, Bin Du wrote:
>>> Amd isp4 capture is a v4l2 media device which implements media
>>> controller
>>
>> AMD
>>
>>> interface.
>>> It has one sub-device (amd ISP4 sub-device) endpoint which can be
>>> connected
>>
>> AMD
>>
>>> to a remote CSI2 TX endpoint. It supports only one physical interface
>>> for
>>> now.
>>> Also add ISP4 driver related entry info into the MAINAINERS file
>>
>> MAINTAINERS
>>
>>>
>>> Signed-off-by: Bin Du <Bin.Du@amd.com>
>>> Signed-off-by: Svetoslav Stoilov <Svetoslav.Stoilov@amd.com>
>>
>> Who actually developed?  If both are developers there should be a Co-
>> developed-by tag.
>>
>>> ---
>>>   MAINTAINERS                              |  10 ++
>>>   drivers/media/platform/Kconfig           |   1 +
>>>   drivers/media/platform/Makefile          |   1 +
>>>   drivers/media/platform/amd/Kconfig       |  17 +++
>>>   drivers/media/platform/amd/Makefile      |   5 +
>>>   drivers/media/platform/amd/isp4/Makefile |  21 ++++
>>>   drivers/media/platform/amd/isp4/isp4.c   | 139 +++++++++++++++++++++++
>>>   drivers/media/platform/amd/isp4/isp4.h   |  35 ++++++
>>>   8 files changed, 229 insertions(+)
>>>   create mode 100644 drivers/media/platform/amd/Kconfig
>>>   create mode 100644 drivers/media/platform/amd/Makefile
>>>   create mode 100644 drivers/media/platform/amd/isp4/Makefile
>>>   create mode 100644 drivers/media/platform/amd/isp4/isp4.c
>>>   create mode 100644 drivers/media/platform/amd/isp4/isp4.h
>>>
>>> diff --git a/MAINTAINERS b/MAINTAINERS
>>> index 10893c91b1c1..15070afb14b5 100644
>>> --- a/MAINTAINERS
>>> +++ b/MAINTAINERS
>>> @@ -1107,6 +1107,16 @@ T:    git git://git.kernel.org/pub/scm/linux/
>>> kernel/git/iommu/linux.git
>>>   F:    drivers/iommu/amd/
>>>   F:    include/linux/amd-iommu.h
>>> +AMD ISP4 DRIVER
>>> +M:    Bin Du <bin.du@amd.com>
>>> +M:    Nirujogi Pratap <pratap.nirujogi@amd.com>
>>> +L:    linux-media@vger.kernel.org
>>> +S:    Maintained
>>> +T:    git git://linuxtv.org/media.git
>>> +F:    drivers/media/platform/amd/Kconfig
>>> +F:    drivers/media/platform/amd/Makefile
>>> +F:    drivers/media/platform/amd/isp4/*
>>> +
>>>   AMD KFD
>>>   M:    Felix Kuehling <Felix.Kuehling@amd.com>
>>>   L:    amd-gfx@lists.freedesktop.org
>>> diff --git a/drivers/media/platform/Kconfig b/drivers/media/platform/
>>> Kconfig
>>> index 85d2627776b6..d525c2262a7d 100644
>>> --- a/drivers/media/platform/Kconfig
>>> +++ b/drivers/media/platform/Kconfig
>>> @@ -89,5 +89,6 @@ source "drivers/media/platform/ti/Kconfig"
>>>   source "drivers/media/platform/verisilicon/Kconfig"
>>>   source "drivers/media/platform/via/Kconfig"
>>>   source "drivers/media/platform/xilinx/Kconfig"
>>> +source "drivers/media/platform/amd/Kconfig"
>>>   endif # MEDIA_PLATFORM_DRIVERS
>>> diff --git a/drivers/media/platform/Makefile b/drivers/media/
>>> platform/ Makefile
>>> index ace4e34483dd..9f3d1693868d 100644
>>> --- a/drivers/media/platform/Makefile
>>> +++ b/drivers/media/platform/Makefile
>>> @@ -32,6 +32,7 @@ obj-y += ti/
>>>   obj-y += verisilicon/
>>>   obj-y += via/
>>>   obj-y += xilinx/
>>> +obj-y += amd/
>>
>> Is this whole file alphabetical?  If so this is the wrong place.
>>
>>>   # Please place here only ancillary drivers that aren't SoC-specific
>>>   # Please keep it alphabetically sorted by Kconfig name
>>> diff --git a/drivers/media/platform/amd/Kconfig b/drivers/media/
>>> platform/amd/Kconfig
>>> new file mode 100644
>>> index 000000000000..3b1dba0400a0
>>> --- /dev/null
>>> +++ b/drivers/media/platform/amd/Kconfig
>>> @@ -0,0 +1,17 @@
>>> +# SPDX-License-Identifier: MIT
>>> +
>>> +config AMD_ISP4
>>> +    tristate "AMD ISP4 and camera driver"
>>> +    default y
>>
>> I don't believe this should default 'y'.  Normally drivers need to be
>> opt in.
>>
>>> +    depends on VIDEO_DEV && VIDEO_V4L2_SUBDEV_API
>>> +    select VIDEOBUF2_CORE
>>> +    select VIDEOBUF2_V4L2
>>> +    select VIDEOBUF2_MEMOPS
>>> +    select VIDEOBUF2_VMALLOC
>>> +    select VIDEOBUF2_DMA_CONTIG
>>> +    select VIDEOBUF2_DMA_SG
>>> +    help
>>> +      This is support for AMD ISP4 and camera subsystem driver.
>>> +      Say Y here to enable the ISP4 and camera device for video
>>> capture.
>>> +      To compile this driver as a module, choose M here. The module
>>> will
>>> +      be called amd_capture.
>>> diff --git a/drivers/media/platform/amd/Makefile b/drivers/media/
>>> platform/amd/Makefile
>>> new file mode 100644
>>> index 000000000000..76146efcd2bf
>>> --- /dev/null
>>> +++ b/drivers/media/platform/amd/Makefile
>>> @@ -0,0 +1,5 @@
>>> +# Copyright 2024 Advanced Micro Devices, Inc.
>>
>> 2025
>>
>>> +# add isp block
>>> +ifneq ($(CONFIG_AMD_ISP4),)
>>> +obj-y += isp4/
>>> +endif
>>> diff --git a/drivers/media/platform/amd/isp4/Makefile b/drivers/
>>> media/ platform/amd/isp4/Makefile
>>> new file mode 100644
>>> index 000000000000..e9e84160517d
>>> --- /dev/null
>>> +++ b/drivers/media/platform/amd/isp4/Makefile
>>> @@ -0,0 +1,21 @@
>>> +# SPDX-License-Identifier: GPL-2.0+
>>> +#
>>> +# Copyright (C) 2025 Advanced Micro Devices, Inc.
>>> +
>>> +obj-$(CONFIG_AMD_ISP4) += amd_capture.o
>>
>> As the directory is already conditional on CONFIG_AMD_ISP4 is this
>> obj- $() needed?  Or should it really be obj-y?
>>
> Yes, it is needed, because AMD_ISP4 is trisate in Kconfig, it can be y or m

Got it, thanks for clarification.

>
>>> +amd_capture-objs := isp4.o
>>> +
>>> +ccflags-y += -I$(srctree)/drivers/media/platform/amd/isp4
>>> +ccflags-y += -I$(srctree)/include
>>> +
>>> +ifneq ($(call cc-option, -mpreferred-stack-boundary=4),)
>>> +    cc_stack_align := -mpreferred-stack-boundary=4
>>> +endif
>>> +
>>> +ccflags-y += $(cc_stack_align)
>>> +ccflags-y += -DCONFIG_COMPAT
>>> +ccflags-y += -Wunused-but-set-variable
>>> +ccflags-y += -Wmissing-include-dirs
>>> +ccflags-y += -Wunused-const-variable
>>> +ccflags-y += -Wmaybe-uninitialized
>>> +ccflags-y += -Wunused-value
>>
>> Do you really need to enforce all these flags just for this driver?
>>
>> Was this just for development to avoid having to remember to call the
>> build with W=1 or CONFIG_WERROR?
>>
> We found after patch submission, Media CI robot test will be triggered,
> when it builds the patch it will set these flags, so adding these flags
> to align with Media CI robot test to discover potential issue before
> submission.

I believe you can just compile with CONFIG_WERROR and get same result,
no? If I'm wrong, nonetheless this should be set in your external build
environment script not in the Makefile to be going upstream.

>
>>> diff --git a/drivers/media/platform/amd/isp4/isp4.c b/drivers/media/
>>> platform/amd/isp4/isp4.c
>>> new file mode 100644
>>> index 000000000000..d0be90c5ec3b
>>> --- /dev/null
>>> +++ b/drivers/media/platform/amd/isp4/isp4.c
>>> @@ -0,0 +1,139 @@
>>> +// SPDX-License-Identifier: GPL-2.0+
>>> +/*
>>> + * Copyright (C) 2025 Advanced Micro Devices, Inc.
>>> + */
>>> +
>>> +#include <linux/pm_runtime.h>
>>> +#include <linux/vmalloc.h>
>>> +#include <media/v4l2-ioctl.h>
>>> +
>>> +#include "isp4.h"
>>> +
>>> +#define VIDEO_BUF_NUM 5
>>> +
>>> +#define ISP4_DRV_NAME "amd_isp_capture"
>>> +
>>> +/* interrupt num */
>>> +static const u32 isp4_ringbuf_interrupt_num[] = {
>>> +    0, /* ISP_4_1__SRCID__ISP_RINGBUFFER_WPT9 */
>>> +    1, /* ISP_4_1__SRCID__ISP_RINGBUFFER_WPT10 */
>>> +    3, /* ISP_4_1__SRCID__ISP_RINGBUFFER_WPT11 */
>>> +    4, /* ISP_4_1__SRCID__ISP_RINGBUFFER_WPT12 */
>>> +};
>>> +
>>> +#define to_isp4_device(dev) \
>>> +    ((struct isp4_device *)container_of(dev, struct isp4_device,
>>> v4l2_dev))
>>> +
>>> +static irqreturn_t isp4_irq_handler(int irq, void *arg)
>>> +{
>>> +    struct isp4_device *isp_dev = dev_get_drvdata((struct device
>>> *)arg);
>>> +
>>> +    if (!isp_dev)
>>> +        goto error_drv_data;
>>> +
>>> +error_drv_data:
>>> +    return IRQ_HANDLED;
>>
>> In patch 5 you change this function, including dropping the goto and
>> label.
>>
>> So I suggest that for patch 1 you KISS:
>>
>> static irqreturn_t isp4_irq_handler(int irq, void *arg)
>> {
>>      return IRQ_HANDLED;
>> }
>>
>> Then in patch 5 add the extra conditional code and real handling.
>>
>>> +}
>>> +
>>> +/*
>>> + * amd capture module
>>> + */
>>
>> Pointless comment, no?
>>
>>> +static int isp4_capture_probe(struct platform_device *pdev)
>>> +{
>>> +    struct device *dev = &pdev->dev;
>>> +    struct isp4_device *isp_dev;
>>> +
>>
>> Why newline here?
>>
>>> +    int i, irq, ret;
>>> +
>>> +    isp_dev = devm_kzalloc(&pdev->dev, sizeof(*isp_dev), GFP_KERNEL);
>>> +    if (!isp_dev)
>>> +        return -ENOMEM;
>>> +
>>> +    isp_dev->pdev = pdev;
>>> +    dev->init_name = ISP4_DRV_NAME;
>>> +
>>> +    for (i = 0; i < ARRAY_SIZE(isp4_ringbuf_interrupt_num); i++) {
>>> +        irq = platform_get_irq(pdev, isp4_ringbuf_interrupt_num[i]);
>>> +        if (irq < 0)
>>> +            return dev_err_probe(dev, -ENODEV,
>>> +                         "fail to get irq %d\n",
>>> +                         isp4_ringbuf_interrupt_num[i]);
>>> +        ret = devm_request_irq(&pdev->dev, irq, isp4_irq_handler, 0,
>>> +                       "ISP_IRQ", &pdev->dev);
>>> +        if (ret)
>>> +            return dev_err_probe(dev, ret, "fail to req irq %d\n",
>>> +                         irq);
>>> +    }
>>> +
>>> +    isp_dev->pltf_data = pdev->dev.platform_data;
>>> +
>>> +    dev_dbg(dev, "isp irq registration successful\n");
>>
>> As you have error handling in place with dev_err_probe() I think the
>> lack of an error implies this message.  I'd say drop it.
>>
>>> +
>>> +    /* Link the media device within the v4l2_device */
>>> +    isp_dev->v4l2_dev.mdev = &isp_dev->mdev;
>>> +
>>> +    /* Initialize media device */
>>> +    strscpy(isp_dev->mdev.model, "amd_isp41_mdev",
>>> +        sizeof(isp_dev->mdev.model));
>>> +    snprintf(isp_dev->mdev.bus_info, sizeof(isp_dev->mdev.bus_info),
>>> +         "platform:%s", ISP4_DRV_NAME);
>>> +    isp_dev->mdev.dev = &pdev->dev;
>>> +    media_device_init(&isp_dev->mdev);
>>> +
>>> +    /* register v4l2 device */
>>> +    snprintf(isp_dev->v4l2_dev.name, sizeof(isp_dev->v4l2_dev.name),
>>> +         "AMD-V4L2-ROOT");
>>> +    ret = v4l2_device_register(&pdev->dev, &isp_dev->v4l2_dev);
>>> +    if (ret)
>>> +        return dev_err_probe(dev, ret,
>>> +                     "fail register v4l2 device\n");
>>> +
>>> +    dev_dbg(dev, "AMD ISP v4l2 device registered\n");
>>
>> As you have error handling in place with dev_err_probe() I think the
>> lack of an error implies this message.  I'd say drop it.
>>
>>> +
>>> +    ret = media_device_register(&isp_dev->mdev);
>>> +    if (ret) {
>>> +        dev_err(dev, "fail to register media device %d\n", ret);
>>> +        goto err_unreg_v4l2;
>>> +    }
>>> +
>>> +    platform_set_drvdata(pdev, isp_dev);
>>> +
>>> +    pm_runtime_set_suspended(dev);
>>> +    pm_runtime_enable(dev);
>>> +
>>> +    return 0;
>>> +
>>> +err_unreg_v4l2:
>>> +    v4l2_device_unregister(&isp_dev->v4l2_dev);
>>> +
>>> +    return dev_err_probe(dev, ret, "isp probe fail\n");
>>> +}
>>> +
>>> +static void isp4_capture_remove(struct platform_device *pdev)
>>> +{
>>> +    struct isp4_device *isp_dev = platform_get_drvdata(pdev);
>>> +    struct device *dev = &pdev->dev;
>>> +
>>> +    media_device_unregister(&isp_dev->mdev);
>>> +    v4l2_device_unregister(&isp_dev->v4l2_dev);
>>> +    dev_dbg(dev, "AMD ISP v4l2 device unregistered\n");
>>
>> Probably not needed message anymore, right?
>>
>>> +}
>>> +
>>> +static struct platform_driver isp4_capture_drv = {
>>> +    .probe = isp4_capture_probe,
>>> +    .remove = isp4_capture_remove,
>>> +    .driver = {
>>> +        .name = ISP4_DRV_NAME,
>>> +        .owner = THIS_MODULE,
>>> +    }
>>> +};
>>> +
>>> +module_platform_driver(isp4_capture_drv);
>>> +
>>> +MODULE_ALIAS("platform:" ISP4_DRV_NAME);
>>> +MODULE_IMPORT_NS("DMA_BUF");
>>> +
>>> +MODULE_DESCRIPTION("AMD ISP4 Driver");
>>> +MODULE_AUTHOR("Bin Du <bin.du@amd.com>");
>>> +MODULE_AUTHOR("Pratap Nirujogi <pratap.nirujogi@amd.com>");
>>> +MODULE_LICENSE("GPL");
>>> diff --git a/drivers/media/platform/amd/isp4/isp4.h b/drivers/media/
>>> platform/amd/isp4/isp4.h
>>> new file mode 100644
>>> index 000000000000..27a7362ce6f9
>>> --- /dev/null
>>> +++ b/drivers/media/platform/amd/isp4/isp4.h
>>> @@ -0,0 +1,35 @@
>>> +/* SPDX-License-Identifier: GPL-2.0+ */
>>> +/*
>>> + * Copyright (C) 2025 Advanced Micro Devices, Inc.
>>> + */
>>> +
>>> +#ifndef _ISP4_H_
>>> +#define _ISP4_H_
>>> +
>>> +#include <linux/mutex.h>
>>> +#include <media/v4l2-device.h>
>>> +#include <media/videobuf2-memops.h>
>>> +#include <media/videobuf2-vmalloc.h>
>>> +
>>> +#define ISP4_GET_ISP_REG_BASE(isp4sd) (((isp4sd))->mmio)
>>> +
>>> +struct isp4_platform_data {
>>> +    void *adev;
>>> +    void *bo;
>>> +    void *cpu_ptr;
>>
>> Will touch more on these in later patches, but I would say don't
>> introduce them until the patch they're needed.
>>
>>> +    u64 gpu_addr;
>>> +    u32 size;
>>> +    u32 asic_type;
>>> +    resource_size_t base_rmmio_size;
>>> +};
>>> +
>>> +struct isp4_device {
>>> +    struct v4l2_device v4l2_dev;
>>> +    struct media_device mdev;
>>> +
>>> +    struct isp4_platform_data *pltf_data;
>>> +    struct platform_device *pdev;
>>> +    struct notifier_block i2c_nb;
>>> +};
>>> +
>>> +#endif /* isp4.h */
>>
>> /* ISP4_H */
>>
>