linux-kernel - Re: [PATCH v11, 01/19] media: mtk-vcodec: Get numbers of register bases from DT

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Message-ID: <5e350a02-eb4b-5080-8d13-fe01ccf5dd70@collabora.com>
Date:   Tue, 30 Nov 2021 14:20:48 +0100
From:   Benjamin Gaignard <benjamin.gaignard@...labora.com>
To:     Yunfei Dong <yunfei.dong@...iatek.com>,
        Alexandre Courbot <acourbot@...omium.org>,
        Hans Verkuil <hverkuil-cisco@...all.nl>,
        Tzung-Bi Shih <tzungbi@...omium.org>,
        Tiffany Lin <tiffany.lin@...iatek.com>,
        Andrew-CT Chen <andrew-ct.chen@...iatek.com>,
        Mauro Carvalho Chehab <mchehab@...nel.org>,
        Rob Herring <robh+dt@...nel.org>,
        Matthias Brugger <matthias.bgg@...il.com>,
        Tomasz Figa <tfiga@...gle.com>
Cc:     Hsin-Yi Wang <hsinyi@...omium.org>,
        Fritz Koenig <frkoenig@...omium.org>,
        Dafna Hirschfeld <dafna.hirschfeld@...labora.com>,
        Daniel Vetter <daniel@...ll.ch>,
        dri-devel <dri-devel@...ts.freedesktop.org>,
        Irui Wang <irui.wang@...iatek.com>,
        linux-media@...r.kernel.org, devicetree@...r.kernel.org,
        linux-kernel@...r.kernel.org, linux-arm-kernel@...ts.infradead.org,
        srv_heupstream@...iatek.com, linux-mediatek@...ts.infradead.org,
        Project_Global_Chrome_Upstream_Group@...iatek.com
Subject: Re: [PATCH v11, 01/19] media: mtk-vcodec: Get numbers of register
 bases from DT


Le 29/11/2021 à 04:41, Yunfei Dong a écrit :
> Different platform may has different numbers of register bases. Gets the
> numbers of register bases from DT (sizeof(u32) * 4 bytes for each).
>
> Reviewed-by: Tzung-Bi Shih<tzungbi@...gle.com>
> Signed-off-by: Yunfei Dong <yunfei.dong@...iatek.com>
> ---
>   .../platform/mtk-vcodec/mtk_vcodec_dec_drv.c  | 37 ++++++++++++++-----
>   1 file changed, 28 insertions(+), 9 deletions(-)
>
> diff --git a/drivers/media/platform/mtk-vcodec/mtk_vcodec_dec_drv.c b/drivers/media/platform/mtk-vcodec/mtk_vcodec_dec_drv.c
> index e6e6a8203eeb..59caf2163349 100644
> --- a/drivers/media/platform/mtk-vcodec/mtk_vcodec_dec_drv.c
> +++ b/drivers/media/platform/mtk-vcodec/mtk_vcodec_dec_drv.c
> @@ -78,6 +78,30 @@ static irqreturn_t mtk_vcodec_dec_irq_handler(int irq, void *priv)
>   	return IRQ_HANDLED;
>   }
>   
> +static int mtk_vcodec_get_reg_bases(struct mtk_vcodec_dev *dev)
> +{
> +	struct platform_device *pdev = dev->plat_dev;
> +	int reg_num, i;
> +
> +	/* Sizeof(u32) * 4 bytes for each register base. */
> +	reg_num = of_property_count_elems_of_size(pdev->dev.of_node, "reg",
> +		sizeof(u32) * 4);

It looks strange for me to have a "reg" size equal to sizeof(u32) * 4. Usually
we more see reg size = sizeof(u32).

> +	if (reg_num <= 0 || reg_num > NUM_MAX_VDEC_REG_BASE) {

If reg_num = NUM_MAX_VDEC_REG_BASE you will iterate out of bounds of dev->reg_base array.
That never happens because dev->reg_base size equal NUM_MAX_VCODEC_REG_BASE.
The question is what is the real needed size for dev->reg_base array ? NUM_MAX_VDEC_REG_BASE or
NUM_MAX_VCODEC_REG_BASE ?

Regards,
Benjamin

> +		dev_err(&pdev->dev, "Invalid register property size: %d\n", reg_num);
> +		return -EINVAL;
> +	}
> +
> +	for (i = 0; i < reg_num; i++) {
> +		dev->reg_base[i] = devm_platform_ioremap_resource(pdev, i);
> +		if (IS_ERR(dev->reg_base[i]))
> +			return PTR_ERR(dev->reg_base[i]);
> +
> +		mtk_v4l2_debug(2, "reg[%d] base=%p", i, dev->reg_base[i]);
> +	}
> +
> +	return 0;
> +}
> +
>   static int fops_vcodec_open(struct file *file)
>   {
>   	struct mtk_vcodec_dev *dev = video_drvdata(file);
> @@ -206,7 +230,7 @@ static int mtk_vcodec_probe(struct platform_device *pdev)
>   	struct resource *res;
>   	phandle rproc_phandle;
>   	enum mtk_vcodec_fw_type fw_type;
> -	int i, ret;
> +	int ret;
>   
>   	dev = devm_kzalloc(&pdev->dev, sizeof(*dev), GFP_KERNEL);
>   	if (!dev)
> @@ -238,14 +262,9 @@ static int mtk_vcodec_probe(struct platform_device *pdev)
>   		goto err_dec_pm;
>   	}
>   
> -	for (i = 0; i < NUM_MAX_VDEC_REG_BASE; i++) {
> -		dev->reg_base[i] = devm_platform_ioremap_resource(pdev, i);
> -		if (IS_ERR((__force void *)dev->reg_base[i])) {
> -			ret = PTR_ERR((__force void *)dev->reg_base[i]);
> -			goto err_res;
> -		}
> -		mtk_v4l2_debug(2, "reg[%d] base=%p", i, dev->reg_base[i]);
> -	}
> +	ret = mtk_vcodec_get_reg_bases(dev);
> +	if (ret)
> +		goto err_res;
>   
>   	res = platform_get_resource(pdev, IORESOURCE_IRQ, 0);
>   	if (res == NULL) {