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Message-ID: <eca4d113-ba59-45aa-9224-22235fb09ddc@bosc.ac.cn>
Date: Wed, 22 May 2024 20:32:53 +0800
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Subject: Re: [v5,3/3] drm/mediatek: Implement OF graphs support for display
 paths
To: AngeloGioacchino Del Regno <angelogioacchino.delregno@collabora.com>,
 chunkuang.hu@kernel.org
Cc: robh@kernel.org, krzysztof.kozlowski+dt@linaro.org, conor+dt@kernel.org,
 p.zabel@pengutronix.de, airlied@gmail.com, daniel@ffwll.ch,
 maarten.lankhorst@linux.intel.com, mripard@kernel.org, tzimmermann@suse.de,
 matthias.bgg@gmail.com, shawn.sung@mediatek.com, yu-chang.lee@mediatek.com,
 ck.hu@mediatek.com, jitao.shi@mediatek.com, devicetree@vger.kernel.org,
 linux-kernel@vger.kernel.org, dri-devel@lists.freedesktop.org,
 linux-mediatek@lists.infradead.org, linux-arm-kernel@lists.infradead.org,
 wenst@chromium.org, kernel@collabora.com,
 Alexandre Mergnat <amergnat@baylibre.com>
References: <20240521075717.50330-4-angelogioacchino.delregno@collabora.com>
Content-Language: en-US, en-AU
From: Sui Jingfeng <suijingfeng@bosc.ac.cn>
Organization: bosc
In-Reply-To: <20240521075717.50330-4-angelogioacchino.delregno@collabora.com>
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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