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From:   Enric Balletbo i Serra <enric.balletbo@collabora.com>
Subject: Re: [PATCH v5 1/8] mtk-mdp: add driver to probe mdp components
To:     Eizan Miyamoto <eizan@chromium.org>, linux-kernel@vger.kernel.org
Cc:     wenst@chromium.org, chunkuang.hu@kernel.org, yong.wu@mediatek.com,
        houlong.wei@mediatek.com,
        Andrew-CT Chen <andrew-ct.chen@mediatek.com>,
        Matthias Brugger <matthias.bgg@gmail.com>,
        Mauro Carvalho Chehab <mchehab@kernel.org>,
        Minghsiu Tsai <minghsiu.tsai@mediatek.com>,
        linux-arm-kernel@lists.infradead.org, linux-media@vger.kernel.org,
        linux-mediatek@lists.infradead.org
References: <20210709022324.1607884-1-eizan@chromium.org>
 <20210709122040.v5.1.Ie6d1e6e39cf9b5d6b2108ae1096af34c3d55880b@changeid>
Message-ID: <a7fc031a-2f28-5be5-f567-ed5f8e57b38f@collabora.com>
Date:   Mon, 12 Jul 2021 12:11:55 +0200
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Hi Eizan,

Thank you for your patch.

On 9/7/21 4:23, Eizan Miyamoto wrote:
> Broadly, this patch (1) adds a driver for various MTK MDP components to
> go alongside the main MTK MDP driver, and (2) hooks them all together
> using the component framework.
> 
> (1) Up until now, the MTK MDP driver controls 8 devices in the device
> tree on its own. When running tests for the hardware video decoder, we
> found that the iommus and LARBs were not being properly configured. To
> configure them, a driver for each be added to mtk_mdp_comp so that
> mtk_iommu_add_device() can (eventually) be called from dma_configure()
> inside really_probe().
> 
> (2) The integration into the component framework allows us to defer the
> registration with the v4l2 subsystem until all the MDP-related devices
> have been probed, so that the relevant device node does not become
> available until initialization of all the components is complete.
> 
> Some notes about how the component framework has been integrated:
> 
> - The driver for the rdma0 component serves double duty as the "master"
>   (aggregate) driver as well as a component driver. This is a non-ideal
>   compromise until a better solution is developed. This device is
>   differentiated from the rest by checking for a "mediatek,vpu" property
>   in the device node.
> 
> - The list of mdp components remains hard-coded as mtk_mdp_comp_dt_ids[]
>   in mtk_mdp_core.c, and as mtk_mdp_comp_driver_dt_match[] in
>   mtk_mdp_comp.c. This unfortunate duplication of information is
>   addressed in a following patch in this series.
> 
> - The component driver calls component_add() for each device that is
>   probed.
> 
> - In mtk_mdp_probe (the "master" device), we scan the device tree for
>   any matching nodes against mtk_mdp_comp_dt_ids, and add component
>   matches for them. The match criteria is a matching device node
>   pointer.
> 
> - When the set of components devices that have been probed corresponds
>   with the list that is generated by the "master", the callback to
>   mtk_mdp_master_bind() is made, which then calls the component bind
>   functions.
> 
> - Inside mtk_mdp_master_bind(), once all the component bind functions
>   have been called, we can then register our device to the v4l2
>   subsystem.
> 
> - The call to pm_runtime_enable() in the master device is called after
>   all the components have been registered by their bind() functions
>   called by mtk_mtp_master_bind(). As a result, the list of components
>   will not change while power management callbacks mtk_mdp_suspend()/
>   resume() are accessing the list of components.
> 
> Signed-off-by: Eizan Miyamoto <eizan@chromium.org>
> ---
> 
> (no changes since v1)
> 
>  drivers/media/platform/mtk-mdp/mtk_mdp_comp.c | 156 +++++++++++++---
>  drivers/media/platform/mtk-mdp/mtk_mdp_comp.h |  25 +--
>  drivers/media/platform/mtk-mdp/mtk_mdp_core.c | 175 +++++++++++++-----
>  drivers/media/platform/mtk-mdp/mtk_mdp_core.h |   1 +
>  4 files changed, 262 insertions(+), 95 deletions(-)
> 
> diff --git a/drivers/media/platform/mtk-mdp/mtk_mdp_comp.c b/drivers/media/platform/mtk-mdp/mtk_mdp_comp.c
> index b3426a551bea..aec1cb5c4261 100644
> --- a/drivers/media/platform/mtk-mdp/mtk_mdp_comp.c
> +++ b/drivers/media/platform/mtk-mdp/mtk_mdp_comp.c
> @@ -5,14 +5,52 @@
>   */
>  
>  #include <linux/clk.h>
> +#include <linux/component.h>
>  #include <linux/device.h>
> -#include <linux/of.h>

You're removing the include ... [1]

> +#include <linux/module.h>
>  #include <linux/of_address.h>
> +#include <linux/of_device.h>

I think this include is not needed, please remove it.

> +#include <linux/of.h>

[1] and adding here again, this change is not needed.

> +#include <linux/of_irq.h>

I think this include is not needed, please remove it.

>  #include <linux/of_platform.h>
>  #include <soc/mediatek/smi.h>
>  
>  #include "mtk_mdp_comp.h"
> -
> +#include "mtk_mdp_core.h"
> +
> +/**
> + * enum mtk_mdp_comp_type - the MDP component
> + * @MTK_MDP_RDMA:		Read DMA
> + * @MTK_MDP_RSZ:		Reszer
> + * @MTK_MDP_WDMA:		Write DMA
> + * @MTK_MDP_WROT:		Write DMA with rotation
> + * @MTK_MDP_COMP_TYPE_MAX:	Placeholder for num elems in this enum
> + */
> +enum mtk_mdp_comp_type {
> +	MTK_MDP_RDMA,
> +	MTK_MDP_RSZ,
> +	MTK_MDP_WDMA,
> +	MTK_MDP_WROT,
> +	MTK_MDP_COMP_TYPE_MAX,

This is not used anywhere, so you can remove it. Introduce it when you need (if
is needed).

> +};
> +
> +static const struct of_device_id mtk_mdp_comp_driver_dt_match[] = {
> +	{
> +		.compatible = "mediatek,mt8173-mdp-rdma",
> +		.data = (void *)MTK_MDP_RDMA
> +	}, {
> +		.compatible = "mediatek,mt8173-mdp-rsz",
> +		.data = (void *)MTK_MDP_RSZ
> +	}, {
> +		.compatible = "mediatek,mt8173-mdp-wdma",
> +		.data = (void *)MTK_MDP_WDMA
> +	}, {
> +		.compatible = "mediatek,mt8173-mdp-wrot",
> +		.data = (void *)MTK_MDP_WROT
> +	},
> +	{ }
> +};
> +MODULE_DEVICE_TABLE(of, mtk_mdp_comp_driver_dt_match);
>  
>  void mtk_mdp_comp_clock_on(struct device *dev, struct mtk_mdp_comp *comp)
>  {
> @@ -21,9 +59,8 @@ void mtk_mdp_comp_clock_on(struct device *dev, struct mtk_mdp_comp *comp)
>  	if (comp->larb_dev) {
>  		err = mtk_smi_larb_get(comp->larb_dev);
>  		if (err)
> -			dev_err(dev,
> -				"failed to get larb, err %d. type:%d\n",
> -				err, comp->type);
> +			dev_err(comp->dev,
> +				"failed to get larb, err %d.\n", err);

I think that if you apply this patch alone it will fail to build. AFAICS there
is no member named 'dev' in 'struct mtk_mdp_comp'.

nit: Now that the limit is 100 chars, this can be in one line.

>  	}
>  
>  	for (i = 0; i < ARRAY_SIZE(comp->clk); i++) {
> @@ -32,8 +69,8 @@ void mtk_mdp_comp_clock_on(struct device *dev, struct mtk_mdp_comp *comp)
>  		err = clk_prepare_enable(comp->clk[i]);
>  		if (err)
>  			dev_err(dev,
> -			"failed to enable clock, err %d. type:%d i:%d\n",
> -				err, comp->type, i);
> +				"failed to enable clock, err %d. i:%d\n",
> +				err, i);

nit: Now that the limit is 100 chars, this can be in one line.

>  	}
>  }
>  
> @@ -51,17 +88,42 @@ void mtk_mdp_comp_clock_off(struct device *dev, struct mtk_mdp_comp *comp)
>  		mtk_smi_larb_put(comp->larb_dev);
>  }
>  
> -int mtk_mdp_comp_init(struct device *dev, struct device_node *node,
> -		      struct mtk_mdp_comp *comp,
> -		      enum mtk_mdp_comp_type comp_type)
> +static int mtk_mdp_comp_bind(struct device *dev, struct device *master,
> +			void *data)

nit: Now that the limit is 100 chars, this can be in one line.

> +{
> +	struct mtk_mdp_comp *comp = dev_get_drvdata(dev);
> +	struct mtk_mdp_dev *mdp = data;
> +
> +	mtk_mdp_register_component(mdp, comp);
> +
> +	return 0;
> +}
> +
> +static void mtk_mdp_comp_unbind(struct device *dev, struct device *master,
> +			   void *data)
> +{
> +	struct mtk_mdp_dev *mdp = data;
> +	struct mtk_mdp_comp *comp = dev_get_drvdata(dev);

nit: reverse x-tree order, like you did just before. First comp, and then mdp.

> +
> +	mtk_mdp_unregister_component(mdp, comp);
> +}
> +
> +static const struct component_ops mtk_mdp_component_ops = {
> +	.bind   = mtk_mdp_comp_bind,
> +	.unbind = mtk_mdp_comp_unbind,
> +};
> +
> +int mtk_mdp_comp_init(struct mtk_mdp_comp *comp, struct device *dev)
>  {
>  	struct device_node *larb_node;
>  	struct platform_device *larb_pdev;
>  	int ret;
>  	int i;
> +	struct device_node *node = dev->of_node;
> +	enum mtk_mdp_comp_type comp_type =
> +		 (enum mtk_mdp_comp_type)of_device_get_match_data(dev);

nit: Now that the limit is 100 chars, this can be in one line. Also maybe apply
the reverse x-tree rule for the new variables?

>  
> -	comp->dev_node = of_node_get(node);
> -	comp->type = comp_type;
> +	INIT_LIST_HEAD(&comp->node);
>  
>  	for (i = 0; i < ARRAY_SIZE(comp->clk); i++) {
>  		comp->clk[i] = of_clk_get(node, i);
> @@ -69,19 +131,19 @@ int mtk_mdp_comp_init(struct device *dev, struct device_node *node,
>  			if (PTR_ERR(comp->clk[i]) != -EPROBE_DEFER)
>  				dev_err(dev, "Failed to get clock\n");
>  			ret = PTR_ERR(comp->clk[i]);
> -			goto put_dev;
> +			goto err;
>  		}
>  
>  		/* Only RDMA needs two clocks */
> -		if (comp->type != MTK_MDP_RDMA)
> +		if (comp_type != MTK_MDP_RDMA)
>  			break;
>  	}
>  
>  	/* Only DMA capable components need the LARB property */
>  	comp->larb_dev = NULL;
> -	if (comp->type != MTK_MDP_RDMA &&
> -	    comp->type != MTK_MDP_WDMA &&
> -	    comp->type != MTK_MDP_WROT)
> +	if (comp_type != MTK_MDP_RDMA &&
> +	    comp_type != MTK_MDP_WDMA &&
> +	    comp_type != MTK_MDP_WROT)

nit: Now that the limit is 100 chars, this can be in one line.

>  		return 0;
>  
>  	larb_node = of_parse_phandle(node, "mediatek,larb", 0);
> @@ -89,7 +151,7 @@ int mtk_mdp_comp_init(struct device *dev, struct device_node *node,
>  		dev_err(dev,
>  			"Missing mediadek,larb phandle in %pOF node\n", node);
>  		ret = -EINVAL;
> -		goto put_dev;
> +		goto err;
>  	}
>  
>  	larb_pdev = of_find_device_by_node(larb_node);
> @@ -97,7 +159,7 @@ int mtk_mdp_comp_init(struct device *dev, struct device_node *node,
>  		dev_warn(dev, "Waiting for larb device %pOF\n", larb_node);
>  		of_node_put(larb_node);
>  		ret = -EPROBE_DEFER;
> -		goto put_dev;
> +		goto err;
>  	}
>  	of_node_put(larb_node);
>  
> @@ -105,13 +167,59 @@ int mtk_mdp_comp_init(struct device *dev, struct device_node *node,
>  
>  	return 0;
>  
> -put_dev:
> -	of_node_put(comp->dev_node);
> -
> +err:
>  	return ret;
>  }
>  
> -void mtk_mdp_comp_deinit(struct device *dev, struct mtk_mdp_comp *comp)
> +static int mtk_mdp_comp_probe(struct platform_device *pdev)
> +{
> +	struct device *dev = &pdev->dev;
> +	struct device_node *vpu_node;
> +	int status;
> +	struct mtk_mdp_comp *comp;

nit: reverse x-tree order.

> +
> +	vpu_node = of_parse_phandle(dev->of_node, "mediatek,vpu", 0);
> +	if (vpu_node) {
> +		of_node_put(vpu_node);
> +		/*
> +		 * The device tree node with a mediatek,vpu property is deemed
> +		 * the MDP "master" device, we don't want to add a component
> +		 * for it in this function because the initialization for the
> +		 * master is done elsewhere.
> +		 */
> +		dev_info(dev, "vpu node found, not probing\n");
> +		return -ENODEV;

For me this is confusing, so you're returning and error but what really want is
just ignore it. On the sub-system I maintain I'd prefer to reduce the dev_info
to dev_dbg and just return 0 here, as is not and error. But I think this code is
removed later, so not sure how important is to change that.


> +	}
> +
> +	comp = devm_kzalloc(dev, sizeof(*comp), GFP_KERNEL);
> +	if (!comp)
> +		return -ENOMEM;
> +
> +	status = mtk_mdp_comp_init(comp, dev);
> +	if (status) {
> +		dev_err(dev, "Failed to initialize component: %d\n", status);
> +		return status;
> +	}
> +
> +	dev_set_drvdata(dev, comp);
> +
> +	return component_add(dev, &mtk_mdp_component_ops);
> +}
> +
> +static int mtk_mdp_comp_remove(struct platform_device *pdev)
>  {
> -	of_node_put(comp->dev_node);
> +	struct device *dev = &pdev->dev;
> +
> +	component_del(dev, &mtk_mdp_component_ops);
> +	return 0;
>  }
> +
> +struct platform_driver mtk_mdp_component_driver = {
> +	.probe          = mtk_mdp_comp_probe,
> +	.remove         = mtk_mdp_comp_remove,
> +	.driver         = {
> +		.name   = "mediatek-mdp-comp",
> +		.owner  = THIS_MODULE,
> +		.of_match_table = mtk_mdp_comp_driver_dt_match,
> +	},
> +};
> diff --git a/drivers/media/platform/mtk-mdp/mtk_mdp_comp.h b/drivers/media/platform/mtk-mdp/mtk_mdp_comp.h
> index 7897766c96bb..b5a18fe567aa 100644
> --- a/drivers/media/platform/mtk-mdp/mtk_mdp_comp.h
> +++ b/drivers/media/platform/mtk-mdp/mtk_mdp_comp.h
> @@ -7,42 +7,23 @@
>  #ifndef __MTK_MDP_COMP_H__
>  #define __MTK_MDP_COMP_H__
>  
> -/**
> - * enum mtk_mdp_comp_type - the MDP component
> - * @MTK_MDP_RDMA:	Read DMA
> - * @MTK_MDP_RSZ:	Riszer
> - * @MTK_MDP_WDMA:	Write DMA
> - * @MTK_MDP_WROT:	Write DMA with rotation
> - */
> -enum mtk_mdp_comp_type {
> -	MTK_MDP_RDMA,
> -	MTK_MDP_RSZ,
> -	MTK_MDP_WDMA,
> -	MTK_MDP_WROT,
> -};
> -
>  /**
>   * struct mtk_mdp_comp - the MDP's function component data
>   * @node:	list node to track sibing MDP components
> - * @dev_node:	component device node
>   * @clk:	clocks required for component
>   * @larb_dev:	SMI device required for component
> - * @type:	component type
>   */
>  struct mtk_mdp_comp {
>  	struct list_head	node;
> -	struct device_node	*dev_node;
>  	struct clk		*clk[2];
>  	struct device		*larb_dev;
> -	enum mtk_mdp_comp_type	type;
>  };
>  
> -int mtk_mdp_comp_init(struct device *dev, struct device_node *node,
> -		      struct mtk_mdp_comp *comp,
> -		      enum mtk_mdp_comp_type comp_type);
> -void mtk_mdp_comp_deinit(struct device *dev, struct mtk_mdp_comp *comp);
> +int mtk_mdp_comp_init(struct mtk_mdp_comp *comp, struct device *dev);
> +
>  void mtk_mdp_comp_clock_on(struct device *dev, struct mtk_mdp_comp *comp);
>  void mtk_mdp_comp_clock_off(struct device *dev, struct mtk_mdp_comp *comp);
>  
> +extern struct platform_driver mtk_mdp_component_driver;
>  
>  #endif /* __MTK_MDP_COMP_H__ */
> diff --git a/drivers/media/platform/mtk-mdp/mtk_mdp_core.c b/drivers/media/platform/mtk-mdp/mtk_mdp_core.c
> index 976aa1f4829b..aca236dbd348 100644
> --- a/drivers/media/platform/mtk-mdp/mtk_mdp_core.c
> +++ b/drivers/media/platform/mtk-mdp/mtk_mdp_core.c
> @@ -6,6 +6,7 @@
>   */
>  
>  #include <linux/clk.h>
> +#include <linux/component.h>
>  #include <linux/device.h>
>  #include <linux/errno.h>
>  #include <linux/interrupt.h>
> @@ -19,6 +20,7 @@
>  #include <linux/workqueue.h>
>  #include <soc/mediatek/smi.h>
>  
> +#include "mtk_mdp_comp.h"
>  #include "mtk_mdp_core.h"
>  #include "mtk_mdp_m2m.h"
>  #include "mtk_vpu.h"
> @@ -32,16 +34,12 @@ module_param(mtk_mdp_dbg_level, int, 0644);
>  static const struct of_device_id mtk_mdp_comp_dt_ids[] = {
>  	{
>  		.compatible = "mediatek,mt8173-mdp-rdma",
> -		.data = (void *)MTK_MDP_RDMA
>  	}, {
>  		.compatible = "mediatek,mt8173-mdp-rsz",
> -		.data = (void *)MTK_MDP_RSZ
>  	}, {
>  		.compatible = "mediatek,mt8173-mdp-wdma",
> -		.data = (void *)MTK_MDP_WDMA
>  	}, {
>  		.compatible = "mediatek,mt8173-mdp-wrot",
> -		.data = (void *)MTK_MDP_WROT
>  	},
>  	{ },
>  };
> @@ -91,6 +89,64 @@ static void mtk_mdp_reset_handler(void *priv)
>  	queue_work(mdp->wdt_wq, &mdp->wdt_work);
>  }
>  
> +static int compare_of(struct device *dev, void *data)
> +{
> +	return dev->of_node == data;
> +}
> +
> +static void release_of(struct device *dev, void *data)
> +{
> +	of_node_put(data);
> +}
> +
> +static int mtk_mdp_master_bind(struct device *dev)
> +{
> +	int status;
> +	struct mtk_mdp_dev *mdp = dev_get_drvdata(dev);

nit: reverse x-tree

> +
> +	mtk_mdp_register_component(mdp, &mdp->comp_self);
> +
> +	status = component_bind_all(dev, mdp);
> +	if (status) {
> +		dev_err(dev, "Failed to bind all components: %d\n", status);
> +		goto err_component_bind_all;
> +	}
> +
> +	status = mtk_mdp_register_m2m_device(mdp);
> +	if (status) {
> +		dev_err(dev, "Failed to register m2m device: %d\n", status);
> +		v4l2_err(&mdp->v4l2_dev, "Failed to init mem2mem device\n");

Duplicated error message, so remove one of them.

> +		goto err_mtk_mdp_register_m2m_device;
> +	}
> +
> +	pm_runtime_enable(dev);
> +
> +	return 0;
> +
> +err_mtk_mdp_register_m2m_device:
> +	component_unbind_all(dev, mdp);
> +
> +err_component_bind_all:
> +	mtk_mdp_unregister_component(mdp, &mdp->comp_self);
> +
> +	return status;
> +}
> +
> +static void mtk_mdp_master_unbind(struct device *dev)
> +{
> +	struct mtk_mdp_dev *mdp = dev_get_drvdata(dev);
> +
> +	pm_runtime_disable(dev);
> +	mtk_mdp_unregister_m2m_device(mdp);
> +	component_unbind_all(dev, mdp);
> +	mtk_mdp_unregister_component(mdp, &mdp->comp_self);
> +}
> +
> +static const struct component_master_ops mtk_mdp_com_ops = {
> +	.bind		= mtk_mdp_master_bind,
> +	.unbind		= mtk_mdp_master_unbind,
> +};
> +
>  void mtk_mdp_register_component(struct mtk_mdp_dev *mdp,
>  				struct mtk_mdp_comp *comp)
>  {
> @@ -108,8 +164,8 @@ static int mtk_mdp_probe(struct platform_device *pdev)
>  	struct mtk_mdp_dev *mdp;
>  	struct device *dev = &pdev->dev;
>  	struct device_node *node, *parent;
> -	struct mtk_mdp_comp *comp, *comp_temp;
> -	int ret = 0;
> +	int i, ret = 0;
> +	struct component_match *match = NULL;
>  
>  	mdp = devm_kzalloc(dev, sizeof(*mdp), GFP_KERNEL);
>  	if (!mdp)
> @@ -134,36 +190,43 @@ static int mtk_mdp_probe(struct platform_device *pdev)
>  	}
>  
>  	/* Iterate over sibling MDP function blocks */
> +	i = 0;
>  	for_each_child_of_node(parent, node) {
> -		const struct of_device_id *of_id;
> -		enum mtk_mdp_comp_type comp_type;
> +		struct platform_device *pdev;
>  
> -		of_id = of_match_node(mtk_mdp_comp_dt_ids, node);
> -		if (!of_id)
> +		if (!of_match_node(mtk_mdp_comp_dt_ids, node))
>  			continue;
>  
> -		if (!of_device_is_available(node)) {
> -			dev_err(dev, "Skipping disabled component %pOF\n",
> -				node);
> +		if (!of_device_is_available(node))
>  			continue;
> -		}
>  
> -		comp_type = (enum mtk_mdp_comp_type)of_id->data;
> -
> -		comp = devm_kzalloc(dev, sizeof(*comp), GFP_KERNEL);
> -		if (!comp) {
> -			ret = -ENOMEM;
> -			of_node_put(node);
> -			goto err_comp;
> +		pdev = of_find_device_by_node(node);
> +		if (!pdev) {
> +			dev_warn(dev, "Unable to find comp device %s\n",
> +				 node->full_name);

nit: Now that the limit is 100 chars, this can be in one line.

> +			continue;
>  		}
>  
> -		ret = mtk_mdp_comp_init(dev, node, comp, comp_type);
> -		if (ret) {
> -			of_node_put(node);
> -			goto err_comp;
> +		/*
> +		 * Do not add a match for my own (rdma0) device node.
> +		 * I will be managing it directly instead using comp_self.
> +		 */
> +		if (&pdev->dev != dev) {
> +			dev_dbg(dev, "adding match %d for: %pOF\n", i++, node);
> +			component_match_add_release(dev, &match, release_of,
> +						    compare_of,
> +						    of_node_get(node));
>  		}
> +	}
>  
> -		mtk_mdp_register_component(mdp, comp);
> +	/*
> +	 * Create a component for myself so that clocks can be toggled in
> +	 * clock_on().
> +	 */
> +	ret = mtk_mdp_comp_init(&mdp->comp_self, dev);
> +	if (ret) {
> +		dev_err(dev, "Failed to initialize component\n");
> +		goto err_comp;
>  	}
>  
>  	mdp->job_wq = create_singlethread_workqueue(MTK_MDP_MODULE_NAME);
> @@ -188,18 +251,12 @@ static int mtk_mdp_probe(struct platform_device *pdev)
>  		goto err_dev_register;
>  	}
>  
> -	ret = mtk_mdp_register_m2m_device(mdp);
> -	if (ret) {
> -		v4l2_err(&mdp->v4l2_dev, "Failed to init mem2mem device\n");
> -		goto err_m2m_register;
> -	}
> -
>  	mdp->vpu_dev = vpu_get_plat_device(pdev);
>  	ret = vpu_wdt_reg_handler(mdp->vpu_dev, mtk_mdp_reset_handler, mdp,
>  				  VPU_RST_MDP);
>  	if (ret) {
>  		dev_err(&pdev->dev, "Failed to register reset handler\n");
> -		goto err_m2m_register;
> +		goto err_wdt_reg;
>  	}
>  
>  	platform_set_drvdata(pdev, mdp);
> @@ -207,15 +264,25 @@ static int mtk_mdp_probe(struct platform_device *pdev)
>  	ret = vb2_dma_contig_set_max_seg_size(&pdev->dev, DMA_BIT_MASK(32));
>  	if (ret) {
>  		dev_err(&pdev->dev, "Failed to set vb2 dma mag seg size\n");
> -		goto err_m2m_register;
> +		goto err_set_max_seg_size;
> +	}
> +
> +	ret = component_master_add_with_match(dev, &mtk_mdp_com_ops, match);
> +	if (ret) {
> +		dev_err(dev, "Component master add failed\n");
> +		goto err_component_master_add;
>  	}
>  
> -	pm_runtime_enable(dev);
>  	dev_dbg(dev, "mdp-%d registered successfully\n", mdp->id);
>  
>  	return 0;
>  
> -err_m2m_register:
> +err_component_master_add:
> +	vb2_dma_contig_clear_max_seg_size(&pdev->dev);
> +
> +err_set_max_seg_size:
> +
> +err_wdt_reg:
>  	v4l2_device_unregister(&mdp->v4l2_dev);
>  
>  err_dev_register:
> @@ -227,11 +294,6 @@ static int mtk_mdp_probe(struct platform_device *pdev)
>  err_alloc_job_wq:
>  
>  err_comp:
> -	list_for_each_entry_safe(comp, comp_temp, &mdp->comp_list, node) {
> -		mtk_mdp_unregister_component(mdp, comp);
> -		mtk_mdp_comp_deinit(dev, comp);
> -	}
> -
>  	dev_dbg(dev, "err %d\n", ret);
>  	return ret;
>  }
> @@ -239,11 +301,10 @@ static int mtk_mdp_probe(struct platform_device *pdev)
>  static int mtk_mdp_remove(struct platform_device *pdev)
>  {
>  	struct mtk_mdp_dev *mdp = platform_get_drvdata(pdev);
> -	struct mtk_mdp_comp *comp, *comp_temp;
>  
> -	pm_runtime_disable(&pdev->dev);
> +	component_master_del(&pdev->dev, &mtk_mdp_com_ops);
> +
>  	vb2_dma_contig_clear_max_seg_size(&pdev->dev);
> -	mtk_mdp_unregister_m2m_device(mdp);
>  	v4l2_device_unregister(&mdp->v4l2_dev);
>  
>  	flush_workqueue(mdp->wdt_wq);
> @@ -252,10 +313,8 @@ static int mtk_mdp_remove(struct platform_device *pdev)
>  	flush_workqueue(mdp->job_wq);
>  	destroy_workqueue(mdp->job_wq);
>  
> -	list_for_each_entry_safe(comp, comp_temp, &mdp->comp_list, node) {
> -		mtk_mdp_unregister_component(mdp, comp);
> -		mtk_mdp_comp_deinit(&pdev->dev, comp);
> -	}
> +	if (!list_empty(&mdp->comp_list))
> +		dev_err(&pdev->dev, "not all components removed\n");

I'm not sure about media, but in most subsystems is not allowed to print and
error and do not return an error. So you should return and error here. Maybe
setup a warning as this is unlikely to happen?

>  
>  	dev_dbg(&pdev->dev, "%s driver unloaded\n", pdev->name);
>  	return 0;
> @@ -310,7 +369,25 @@ static struct platform_driver mtk_mdp_driver = {
>  	}
>  };
>  
> -module_platform_driver(mtk_mdp_driver);
> +static struct platform_driver * const mtk_mdp_drivers[] = {
> +	&mtk_mdp_driver,
> +	&mtk_mdp_component_driver,
> +};
> +
> +static int __init mtk_mdp_init(void)
> +{
> +	return platform_register_drivers(mtk_mdp_drivers,
> +					 ARRAY_SIZE(mtk_mdp_drivers));
> +}
> +
> +static void __exit mtk_mdp_exit(void)
> +{
> +	platform_unregister_drivers(mtk_mdp_drivers,
> +				    ARRAY_SIZE(mtk_mdp_drivers));
> +}
> +
> +module_init(mtk_mdp_init);
> +module_exit(mtk_mdp_exit);
>  
>  MODULE_AUTHOR("Houlong Wei <houlong.wei@mediatek.com>");
>  MODULE_DESCRIPTION("Mediatek image processor driver");

I know this is not related to this patch, but is this driver really a "Mediatek
Image Processor driver"? When I read this I understand it is a ISP.

> diff --git a/drivers/media/platform/mtk-mdp/mtk_mdp_core.h b/drivers/media/platform/mtk-mdp/mtk_mdp_core.h
> index a6e6dc36307b..8a52539b15d4 100644
> --- a/drivers/media/platform/mtk-mdp/mtk_mdp_core.h
> +++ b/drivers/media/platform/mtk-mdp/mtk_mdp_core.h
> @@ -155,6 +155,7 @@ struct mtk_mdp_dev {
>  	struct mtk_mdp_variant		*variant;
>  	u16				id;
>  	struct list_head		comp_list;
> +	struct mtk_mdp_comp		comp_self;
>  	struct v4l2_m2m_dev		*m2m_dev;
>  	struct list_head		ctx_list;
>  	struct video_device		*vdev;
>