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Date:   Mon, 23 Aug 2021 18:01:40 +0800
From:   Tzung-Bi Shih <tzungbi@google.com>
To:     Irui Wang <irui.wang@mediatek.com>
Cc:     Hans Verkuil <hverkuil-cisco@xs4all.nl>,
        Tzung-Bi Shih <tzungbi@chromium.org>,
        Alexandre Courbot <acourbot@chromium.org>,
        Tiffany Lin <tiffany.lin@mediatek.com>,
        Andrew-CT Chen <andrew-ct.chen@mediatek.com>,
        Mauro Carvalho Chehab <mchehab@kernel.org>,
        Rob Herring <robh+dt@kernel.org>,
        Matthias Brugger <matthias.bgg@gmail.com>,
        Tomasz Figa <tfiga@google.com>, Yong Wu <yong.wu@mediatek.com>,
        Hsin-Yi Wang <hsinyi@chromium.org>,
        Maoguang Meng <maoguang.meng@mediatek.com>,
        Longfei Wang <longfei.wang@mediatek.com>,
        Yunfei Dong <yunfei.dong@mediatek.com>,
        Fritz Koenig <frkoenig@chromium.org>,
        linux-media@vger.kernel.org, devicetree@vger.kernel.org,
        linux-kernel@vger.kernel.org, linux-arm-kernel@lists.infradead.org,
        srv_heupstream@mediatek.com, linux-mediatek@lists.infradead.org,
        Project_Global_Chrome_Upstream_Group@mediatek.com
Subject: Re: [PATCH 2/9] media: mtk-vcodec: Use component framework to manage
 encoder hardware
Message-ID: <YSNyBE4yF6VDt3cC@google.com>
References: <20210816105934.28265-1-irui.wang@mediatek.com>
 <20210816105934.28265-3-irui.wang@mediatek.com>
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In-Reply-To: <20210816105934.28265-3-irui.wang@mediatek.com>
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On Mon, Aug 16, 2021 at 06:59:27PM +0800, Irui Wang wrote:
> +static struct component_match *mtk_venc_match_add(struct mtk_vcodec_dev *dev)
> +{
> +	struct platform_device *pdev = dev->plat_dev;
> +	struct component_match *match = NULL;
> +	int i;
> +
> +	for (i = 0; i < ARRAY_SIZE(mtk_venc_comp_ids); i++) {
> +		enum mtk_venc_hw_id comp_idx;
> +		struct device_node *comp_node;
> +		const struct of_device_id *of_id;
To be neat, prefer to define the variables outside of the loop (i.e. at the beginning of the function).

> +
> +		comp_node = of_find_compatible_node(NULL, NULL,
> +			mtk_venc_comp_ids[i].compatible);
> +		if (!comp_node)
> +			continue;
> +
> +		of_id = of_match_node(mtk_venc_comp_ids, comp_node);
> +		if (!of_id) {
> +			dev_err(&pdev->dev, "Failed to get match node\n");
Need to call of_node_put() actually, but see comment below.

> +			return ERR_PTR(-EINVAL);
> +		}
> +
> +		comp_idx = (enum mtk_venc_hw_id)of_id->data;
For getting the comp_idx, mtk_venc_comp_ids[i].data should be sufficient.  If so, of_match_node() can be removed so that the error handling path won't need to call of_node_put().

> @@ -239,6 +314,7 @@ static int mtk_vcodec_probe(struct platform_device *pdev)
>  	phandle rproc_phandle;
>  	enum mtk_vcodec_fw_type fw_type;
>  	int ret;
> +	struct component_match *match = NULL;
It doesn't need to be initialized.

> -	res = platform_get_resource(pdev, IORESOURCE_IRQ, 0);
> -	if (res == NULL) {
> -		dev_err(&pdev->dev, "failed to get irq resource");
> -		ret = -ENOENT;
> -		goto err_res;
> -	}
> +		res = platform_get_resource(pdev, IORESOURCE_IRQ, 0);
> +		if (!res) {
> +			dev_err(&pdev->dev, "failed to get irq resource");
> +			ret = -ENOENT;
> +			goto err_res;
> +		}
res is not used.  Can be removed in next version or in another patch.

> diff --git a/drivers/media/platform/mtk-vcodec/mtk_vcodec_enc_hw.c b/drivers/media/platform/mtk-vcodec/mtk_vcodec_enc_hw.c
> new file mode 100644
> index 000000000000..4e6a8a81ff67
> --- /dev/null
> +++ b/drivers/media/platform/mtk-vcodec/mtk_vcodec_enc_hw.c
> @@ -0,0 +1,179 @@
> +// SPDX-License-Identifier: GPL-2.0
> +/*
> + * Copyright (c) 2021 MediaTek Inc.
> + */
> +
> +#include <linux/pm_runtime.h>
> +#include <linux/interrupt.h>
> +#include <linux/irq.h>
> +#include <linux/of_platform.h>
> +#include <linux/module.h>
Would be better to maintain an order.

> +#include "mtk_vcodec_enc_hw.h"
> +#include "mtk_vcodec_enc.h"
Would be better to maintain an order.

> +static irqreturn_t mtk_enc_comp_irq_handler(int irq, void *priv)
> +{
> +	struct mtk_venc_comp_dev *dev = priv;
> +	struct mtk_vcodec_ctx *ctx;
> +	unsigned long flags;
> +	void __iomem *addr;
> +
> +	spin_lock_irqsave(&dev->master_dev->irqlock, flags);
> +	ctx = dev->curr_ctx;
> +	spin_unlock_irqrestore(&dev->master_dev->irqlock, flags);
> +	if (!ctx)
> +		return IRQ_HANDLED;
Here is a read lock for the curr_ctx.  The patch doesn't contain the write lock part.

I am not sure if the following situation would be happened:
1. curr_ctx is not NULL.
2. mtk_enc_comp_irq_handler() gets the curr_ctx.
3. The curr_ctx has been destroyed somewhere.
4. mtk_enc_comp_irq_handler() finds the ctx is not NULL so that it continues to execute.
5. Something wrong in latter mtk_enc_comp_irq_handler() because the ctx has been destroyed.

Does it make more sense to set curr_ctx to NULL to indicate the ownership has been transferred to mtk_enc_comp_irq_handler()?  For example:

spin_lock_irqsave(...);
ctx = dev->curr_ctx;
dev->curr_ctx = NULL;
spin_unlock_irqrestore(...);

> +static int mtk_venc_comp_bind(struct device *dev,
> +			      struct device *master, void *data)
> +{
> +	struct mtk_venc_comp_dev *comp_dev = dev_get_drvdata(dev);
> +	struct mtk_vcodec_dev *master_dev = data;
> +	int i;
> +
> +	for (i = 0; i < MTK_VENC_HW_MAX; i++) {
> +		if (dev->of_node != master_dev->enc_comp_node[i])
> +			continue;
> +
> +		/*add component device by order*/
> +		if (comp_dev->core_id == MTK_VENC_CORE0)
> +			master_dev->enc_comp_dev[MTK_VENC_CORE0] = comp_dev;
> +		else if (comp_dev->core_id == MTK_VENC_CORE1)
> +			master_dev->enc_comp_dev[MTK_VENC_CORE1] = comp_dev;
> +		else
> +			return -EINVAL;
if (comp_dev->core_id < 0 || comp_dev->core_id >= MTK_VENC_HW_MAX)
    return -EINVAL;

master_dev->enc_comp_dev[comp_dev->core_id] = comp_dev;