Re: [PATCH 3/8] drm/mediatek: mt2701: switch to mfd probing.

[CK Hu]

Hi, Matthias:

On Tue, 2017-11-14 at 22:41 +0100, Matthias Brugger wrote:
> With the mtk-mmsys MFD device in place, we switch the probing for
> mt2701 from device-tree to mfd.
> 
> Signed-off-by: Matthias Brugger <mbrugger@xxxxxxxx>
> ---
>  drivers/gpu/drm/mediatek/mtk_drm_drv.c | 32 +++++++++++++++++++++++++-------
>  1 file changed, 25 insertions(+), 7 deletions(-)
> 
> diff --git a/drivers/gpu/drm/mediatek/mtk_drm_drv.c b/drivers/gpu/drm/mediatek/mtk_drm_drv.c
> index dd249cf5121e..5a263aa3ab6e 100644
> --- a/drivers/gpu/drm/mediatek/mtk_drm_drv.c
> +++ b/drivers/gpu/drm/mediatek/mtk_drm_drv.c
> @@ -21,6 +21,7 @@
>  #include <drm/drm_of.h>
>  #include <linux/component.h>
>  #include <linux/iommu.h>
> +#include <linux/mfd/mmsys.h>
>  #include <linux/mfd/syscon.h>
>  #include <linux/of_address.h>
>  #include <linux/of_platform.h>
> @@ -392,9 +393,10 @@ static const struct of_device_id mtk_ddp_comp_dt_ids[] = {
>  
>  static int mtk_drm_probe(struct platform_device *pdev)
>  {
> +	struct mmsys_dev *mmsys_private;
>  	struct device *dev = &pdev->dev;
>  	struct mtk_drm_private *private;
> -	struct device_node *node;
> +	struct device_node *node, *parent_node;
>  	struct component_match *match = NULL;
>  	int ret;
>  	int i;
> @@ -407,12 +409,23 @@ static int mtk_drm_probe(struct platform_device *pdev)
>  	INIT_WORK(&private->commit.work, mtk_atomic_work);
>  	private->data = of_device_get_match_data(dev);
>  
> -	private->config_regs = syscon_node_to_regmap(dev->of_node);
> -	if (IS_ERR(private->config_regs))
> -		return PTR_ERR(private->config_regs);
> +	/* Check if called from mfd */
> +	if (!dev->of_node) {
> +		mmsys_private = dev_get_drvdata(pdev->dev.parent);

Why do you directly access parent's driver data? You just need the
device node of mmsys, maybe you could refer to [1].

[1]
https://elixir.free-electrons.com/linux/latest/source/drivers/reset/reset-berlin.c#L78

Regards,
CK

> +		private->data = (struct mtk_mmsys_driver_data *)
> +				platform_get_device_id(pdev)->driver_data;
> +		private->config_regs =
> +			syscon_node_to_regmap(mmsys_private->of_node);
> +		parent_node = mmsys_private->of_node->parent;
> +	} else {
> +		private->config_regs = syscon_node_to_regmap(dev->of_node);
> +		if (IS_ERR(private->config_regs))
> +			return PTR_ERR(private->config_regs);
> +		parent_node = dev->of_node->parent;
> +	}
>  
>  	/* Iterate over sibling DISP function blocks */
> -	for_each_child_of_node(dev->of_node->parent, node) {
> +	for_each_child_of_node(parent_node, node) {
>  		const struct of_device_id *of_id;
>  		enum mtk_ddp_comp_type comp_type;
>  		int comp_id;
> @@ -553,13 +566,17 @@ static SIMPLE_DEV_PM_OPS(mtk_drm_pm_ops, mtk_drm_sys_suspend,
>  			 mtk_drm_sys_resume);
>  
>  static const struct of_device_id mtk_drm_of_ids[] = {
> -	{ .compatible = "mediatek,mt2701-mmsys",
> -	  .data = &mt2701_mmsys_driver_data},
>  	{ .compatible = "mediatek,mt8173-mmsys",
>  	  .data = &mt8173_mmsys_driver_data},
>  	{ }
>  };
>  
> +static const struct platform_device_id mtk_drm_ids[] = {
> +	{ "drm-mt2701-mm", (kernel_ulong_t)&mt2701_mmsys_driver_data },
> +	{ /* sentinel */ },
> +};
> +MODULE_DEVICE_TABLE(platform, mtk_drm_ids);
> +
>  static struct platform_driver mtk_drm_platform_driver = {
>  	.probe	= mtk_drm_probe,
>  	.remove	= mtk_drm_remove,
> @@ -568,6 +585,7 @@ static struct platform_driver mtk_drm_platform_driver = {
>  		.of_match_table = mtk_drm_of_ids,
>  		.pm     = &mtk_drm_pm_ops,
>  	},
> +	.id_table = mtk_drm_ids,
>  };
>  
>  static struct platform_driver * const mtk_drm_drivers[] = {