linux-kernel - Re: [v5,3/3] drm/mediatek: Implement OF graphs support for display paths

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Message-ID: <eca4d113-ba59-45aa-9224-22235fb09ddc@bosc.ac.cn>
Date: Wed, 22 May 2024 20:32:53 +0800
From: Sui Jingfeng <suijingfeng@...c.ac.cn>
To: AngeloGioacchino Del Regno <angelogioacchino.delregno@...labora.com>,
 chunkuang.hu@...nel.org
Cc: robh@...nel.org, krzysztof.kozlowski+dt@...aro.org, conor+dt@...nel.org,
 p.zabel@...gutronix.de, airlied@...il.com, daniel@...ll.ch,
 maarten.lankhorst@...ux.intel.com, mripard@...nel.org, tzimmermann@...e.de,
 matthias.bgg@...il.com, shawn.sung@...iatek.com, yu-chang.lee@...iatek.com,
 ck.hu@...iatek.com, jitao.shi@...iatek.com, devicetree@...r.kernel.org,
 linux-kernel@...r.kernel.org, dri-devel@...ts.freedesktop.org,
 linux-mediatek@...ts.infradead.org, linux-arm-kernel@...ts.infradead.org,
 wenst@...omium.org, kernel@...labora.com,
 Alexandre Mergnat <amergnat@...libre.com>
Subject: Re: [v5,3/3] drm/mediatek: Implement OF graphs support for display
 paths

Hi,


On 5/21/24 15:57, AngeloGioacchino Del Regno wrote:
> +static int mtk_drm_of_ddp_path_build(struct device *dev, struct device_node *node,
> +				     struct mtk_mmsys_driver_data *data)
> +{
> +	struct device_node *ep_node;
> +	struct of_endpoint of_ep;
> +	bool output_present[MAX_CRTC] = { false };
> +	int ret;
> +
> +	for_each_endpoint_of_node(node, ep_node) {
> +		ret = of_graph_parse_endpoint(ep_node, &of_ep);
> +		of_node_put(ep_node);

There is going to *double* decline the reference counter, as the 
__of_get_next_child() will decrease the reference counter for us
on the next iteration.


> +		if (ret) {
> +			dev_err_probe(dev, ret, "Cannot parse endpoint\n");
> +			break;
> +		}

Move the 'of_node_put(ep_node)' into brace '{}' here, if we really cares
about the reference count.

> +
> +		if (of_ep.id >= MAX_CRTC) {

ditto ?

> +			ret = dev_err_probe(dev, -EINVAL,
> +					    "Invalid endpoint%u number\n", of_ep.port);
> +			break;
> +		}
> +
> +		output_present[of_ep.id] = true;
> +	}
> +
> +	if (ret)
> +		return ret;
> +
> +	if (output_present[CRTC_MAIN]) {
> +		ret = mtk_drm_of_ddp_path_build_one(dev, CRTC_MAIN,
> +						    &data->main_path, &data->main_len);
> +		if (ret)
> +			return ret;
> +	}
> +
> +	if (output_present[CRTC_EXT]) {
> +		ret = mtk_drm_of_ddp_path_build_one(dev, CRTC_EXT,
> +						    &data->ext_path, &data->ext_len);
> +		if (ret)
> +			return ret;
> +	}
> +
> +	if (output_present[CRTC_THIRD]) {
> +		ret = mtk_drm_of_ddp_path_build_one(dev, CRTC_THIRD,
> +						    &data->third_path, &data->third_len);
> +		if (ret)
> +			return ret;
> +	}
> +
> +	return 0;
> +}
> +

-- 
Best regards
Sui Jingfeng