On Mon, May 27, 2024 at 03:58:24AM +0800, Sui Jingfeng wrote:
> In some display subsystems, the functionality of a PCIe device may too
> complex to be managed by a single driver. A split of the functionality
> into child devices can helpful to achieve better modularity.
>
> Another benefit is that we could migrate the dependency on exterinal
> modules to a submodule level with the helper created. For example, it's
> not uncommon that some exterinal module will return -EPROBE_DEFER to our
> driver during probe time. KMS driver has to tear down everything when it
> receives -EPROBE_DEFER, the problem is that it's completely not necessary
> and rising cyclic dependency problems if not process correctly.
>
> Add the loongson_create_platform_device() function, which allows the KMS
> driver to create sub-devices for it. The manually created decice acts as
> agents for the principal part, migrate the potential issue to submodule.
>
> Signed-off-by: Sui Jingfeng <sui.jingfeng@xxxxxxxxx>
> ---
> drivers/gpu/drm/loongson/loongson_device.c | 42 ++++++++++++++++++++++
> drivers/gpu/drm/loongson/lsdc_drv.h | 6 ++++
> 2 files changed, 48 insertions(+)
>
> diff --git a/drivers/gpu/drm/loongson/loongson_device.c b/drivers/gpu/drm/loongson/loongson_device.c
> index 9986c8a2a255..b268549d643e 100644
> --- a/drivers/gpu/drm/loongson/loongson_device.c
> +++ b/drivers/gpu/drm/loongson/loongson_device.c
> @@ -4,6 +4,7 @@
> */
>
> #include <linux/pci.h>
> +#include <linux/platform_device.h>
>
> #include "lsdc_drv.h"
>
> @@ -100,3 +101,44 @@ lsdc_device_probe(struct pci_dev *pdev, enum loongson_chip_id chip_id)
> {
> return __chip_id_desc_table[chip_id];
> }
> +
> +int loongson_create_platform_device(struct device *parent,
> + const char *name, int id,
> + struct resource *pres,
> + void *data,
> + struct platform_device **ppdev)
> +{
> + struct platform_device *pdev;
> + int ret;
> +
> + pdev = platform_device_alloc(name, id);
> + if (!pdev)
> + return -ENOMEM;
> +
> + pdev->dev.parent = parent;
> +
> + if (pres) {
> + ret = platform_device_add_resources(pdev, pres, 1);
> + if (ret) {
> + platform_device_put(pdev);
> + return ret;
> + }
> + }
> +
> + if (data) {
> + void *pdata = kmalloc(sizeof(void *), GFP_KERNEL);
> +
> + *(void **)pdata = data;
> + pdev->dev.platform_data = pdata;
> + }
> +
> + ret = platform_device_add(pdev);
> + if (ret) {
> + platform_device_put(pdev);
> + return ret;
> + }
Please use platform_device_register_resndata().
> +
> + *ppdev = pdev;
> +
> + return 0;
> +}
> diff --git a/drivers/gpu/drm/loongson/lsdc_drv.h b/drivers/gpu/drm/loongson/lsdc_drv.h
> index fbf2d760ef27..a2c6b496a69f 100644
> --- a/drivers/gpu/drm/loongson/lsdc_drv.h
> +++ b/drivers/gpu/drm/loongson/lsdc_drv.h
> @@ -47,6 +47,12 @@ enum loongson_chip_id {
> const struct lsdc_desc *
> lsdc_device_probe(struct pci_dev *pdev, enum loongson_chip_id chip);
>
> +int loongson_create_platform_device(struct device *parent,
> + const char *name, int id,
> + struct resource *pres,
> + void *data,
> + struct platform_device **ppdev);
> +
> struct lsdc_kms_funcs;
>
> /* DC specific */
> --
> 2.34.1
>
--
With best wishes
Dmitry
