Re: [PATCH v8 3/5] staging: bcm2835-camera: Register bcm2835-camera with vchiq_bus_type

Kieran Bingham
2023-06-28T22:44:36Z

Quoting Umang Jain (2023-06-27 21:16:26)
> Register the bcm2835-camera with the vchiq_bus_type instead of using
> platform driver/device.
>
> Also the VCHIQ firmware doesn't support device enumeration, hence
> one has to maintain a list of devices to be registered in the interface.
>
> Signed-off-by: Umang Jain <umang.jain@ideasonboard.com>
> ---
> .../bcm2835-camera/bcm2835-camera.c | 16 +++++++-------
> .../interface/vchiq_arm/vchiq_arm.c | 21 ++++++++++++++++---
> 2 files changed, 26 insertions(+), 11 deletions(-)
>
> diff --git a/drivers/staging/vc04_services/bcm2835-camera/bcm2835-camera.c b/drivers/staging/vc04_services/bcm2835-camera/bcm2835-camera.c
> index 346d00df815a..f37b2a881d92 100644
> --- a/drivers/staging/vc04_services/bcm2835-camera/bcm2835-camera.c
> +++ b/drivers/staging/vc04_services/bcm2835-camera/bcm2835-camera.c
> @@ -24,8 +24,9 @@
> #include <media/v4l2-event.h>
> #include <media/v4l2-common.h>
> #include <linux/delay.h>
> -#include <linux/platform_device.h>
>
> +#include "../interface/vchiq_arm/vchiq_arm.h"
> +#include "../interface/vchiq_arm/vchiq_device.h"
> #include "../vchiq-mmal/mmal-common.h"
> #include "../vchiq-mmal/mmal-encodings.h"
> #include "../vchiq-mmal/mmal-vchiq.h"
> @@ -1841,7 +1842,7 @@ static struct v4l2_format default_v4l2_format = {
> .fmt.pix.sizeimage = 1024 * 768,
> };
>
> -static int bcm2835_mmal_probe(struct platform_device *pdev)
> +static int bcm2835_mmal_probe(struct vchiq_device *device)
> {
> int ret;
> struct bcm2835_mmal_dev *dev;
> @@ -1896,7 +1897,7 @@ static int bcm2835_mmal_probe(struct platform_device *pdev)
> &camera_instance);
> ret = v4l2_device_register(NULL, &dev->v4l2_dev);
> if (ret) {
> - dev_err(&pdev->dev, "%s: could not register V4L2 device: %d\n",
> + dev_err(&device->dev, "%s: could not register V4L2 device: %d\n",
> __func__, ret);
> goto free_dev;
> }
> @@ -1976,7 +1977,7 @@ static int bcm2835_mmal_probe(struct platform_device *pdev)
> return ret;
> }
>
> -static void bcm2835_mmal_remove(struct platform_device *pdev)
> +static void bcm2835_mmal_remove(struct vchiq_device *device)
> {
> int camera;
> struct vchiq_mmal_instance *instance = gdev[0]->instance;
> @@ -1988,17 +1989,16 @@ static void bcm2835_mmal_remove(struct platform_device *pdev)
> vchiq_mmal_finalise(instance);
> }
>
> -static struct platform_driver bcm2835_camera_driver = {
> +static struct vchiq_driver bcm2835_camera_driver = {
> .probe = bcm2835_mmal_probe,
> - .remove_new = bcm2835_mmal_remove,
> + .remove = bcm2835_mmal_remove,
> .driver = {
> .name = "bcm2835-camera",
> },
> };
>
> -module_platform_driver(bcm2835_camera_driver)
> +module_vchiq_driver(bcm2835_camera_driver)
>
> MODULE_DESCRIPTION("Broadcom 2835 MMAL video capture");
> MODULE_AUTHOR("Vincent Sanders");
> MODULE_LICENSE("GPL");
> -MODULE_ALIAS("platform:bcm2835-camera");

This bit worries me. I think that's how module autoloading is handled.

Can you check into the details of MODULE_ALIAS and follow the rabbit
hole for a bit? It's a few years since I last went down there so I can't
remember the specifics right now.

Except for that, I think this looks good.

> diff --git a/drivers/staging/vc04_services/interface/vchiq_arm/vchiq_arm.c b/drivers/staging/vc04_services/interface/vchiq_arm/vchiq_arm.c
> index e8d40f891449..79d4d0eeb5fb 100644
> --- a/drivers/staging/vc04_services/interface/vchiq_arm/vchiq_arm.c
> +++ b/drivers/staging/vc04_services/interface/vchiq_arm/vchiq_arm.c
> @@ -67,7 +67,6 @@ int vchiq_susp_log_level = VCHIQ_LOG_ERROR;
> DEFINE_SPINLOCK(msg_queue_spinlock);
> struct vchiq_state g_state;
>
> -static struct platform_device *bcm2835_camera;
> static struct platform_device *bcm2835_audio;
>
> struct vchiq_drvdata {
> @@ -134,6 +133,15 @@ struct vchiq_pagelist_info {
> unsigned int scatterlist_mapped;
> };
>
> +/*
> + * The devices implemented in the VCHIQ firmware are not discoverable,
> + * so we need to maintain a list of them in order to register them with
> + * the interface.
> + */
> +static const char *const vchiq_devices[] = {
> + "bcm2835-camera",
> +};
> +
> static void __iomem *g_regs;
> /* This value is the size of the L2 cache lines as understood by the
> * VPU firmware, which determines the required alignment of the
> @@ -1798,6 +1806,7 @@ static int vchiq_probe(struct platform_device *pdev)
> struct device_node *fw_node;
> const struct of_device_id *of_id;
> struct vchiq_drvdata *drvdata;
> + unsigned int i;
> int err;
>
> of_id = of_match_node(vchiq_of_match, pdev->dev.of_node);
> @@ -1840,9 +1849,15 @@ static int vchiq_probe(struct platform_device *pdev)
> goto error_exit;
> }
>
> - bcm2835_camera = vchiq_register_child(pdev, "bcm2835-camera");
> bcm2835_audio = vchiq_register_child(pdev, "bcm2835_audio");
>
> + for (i = 0; i < ARRAY_SIZE(vchiq_devices); i++) {
> + err = vchiq_device_register(&pdev->dev, vchiq_devices[i]);
> + if (err)
> + dev_err(&pdev->dev, "Failed to register %s vchiq device\n",
> + vchiq_devices[i]);
> + }
> +
> return 0;
>
> failed_platform_init:
> @@ -1854,7 +1869,7 @@ static int vchiq_probe(struct platform_device *pdev)
> static void vchiq_remove(struct platform_device *pdev)
> {
> platform_device_unregister(bcm2835_audio);
> - platform_device_unregister(bcm2835_camera);
> + bus_for_each_dev(&vchiq_bus_type, NULL, NULL, vchiq_device_unregister);
> vchiq_debugfs_deinit();
> vchiq_deregister_chrdev();
> }
> --
> 2.39.1
>