linux-kernel - Re: [PATCH v8 3/8] drm/mediatek: Fix using wrong drm private data to bind mediatek-drm

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Message-ID: <3d5de892-8311-86e8-b962-0e564903b0e6@collabora.com>
Date:   Thu, 3 Aug 2023 16:22:45 +0300
From:   Eugen Hristev <eugen.hristev@...labora.com>
To:     "Jason-JH.Lin" <jason-jh.lin@...iatek.com>,
        Chun-Kuang Hu <chunkuang.hu@...nel.org>,
        AngeloGioacchino Del Regno 
        <angelogioacchino.delregno@...labora.com>
Cc:     Matthias Brugger <matthias.bgg@...il.com>,
        Jason-ch Chen <jason-ch.chen@...iatek.com>,
        Johnson Wang <johnson.wang@...iatek.com>,
        Singo Chang <singo.chang@...iatek.com>,
        Nancy Lin <nancy.lin@...iatek.com>,
        Shawn Sung <shawn.sung@...iatek.com>,
        dri-devel@...ts.freedesktop.org,
        linux-mediatek@...ts.infradead.org,
        linux-arm-kernel@...ts.infradead.org, linux-kernel@...r.kernel.org,
        Project_Global_Chrome_Upstream_Group@...iatek.com
Subject: Re: [PATCH v8 3/8] drm/mediatek: Fix using wrong drm private data to
 bind mediatek-drm

On 8/2/23 17:47, Jason-JH.Lin wrote:
> In mtk_drm_kms_init(), each element in all_drm_priv should has one
> display path private data only, such as:
> all_drm_priv[CRTC_MAIN] should has main_path data only
> all_drm_priv[CRTC_EXT] should has ext_path data only
> all_drm_priv[CRTC_THIRD] should has third_path data only

s/should has/should have/ ?

> 
> So we need to add the length checking for each display path before
> assigning their drm private data into all_drm_priv array.
> 
> Fixes: 1ef7ed48356c ("drm/mediatek: Modify mediatek-drm for mt8195 multi mmsys support")
> Signed-off-by: Jason-JH.Lin <jason-jh.lin@...iatek.com>
> Reviewed-by: AngeloGioacchino Del Regno <angelogioacchino.delregno@...labora.com>
> Reviewed-by: CK Hu <ck.hu@...iatek.com>
> ---
>   drivers/gpu/drm/mediatek/mtk_drm_drv.c | 16 +++++++++++++---
>   1 file changed, 13 insertions(+), 3 deletions(-)
> 
> diff --git a/drivers/gpu/drm/mediatek/mtk_drm_drv.c b/drivers/gpu/drm/mediatek/mtk_drm_drv.c
> index 89a38561ba27..c12886f31e54 100644
> --- a/drivers/gpu/drm/mediatek/mtk_drm_drv.c
> +++ b/drivers/gpu/drm/mediatek/mtk_drm_drv.c
> @@ -351,6 +351,7 @@ static bool mtk_drm_get_all_drm_priv(struct device *dev)
>   {
>   	struct mtk_drm_private *drm_priv = dev_get_drvdata(dev);
>   	struct mtk_drm_private *all_drm_priv[MAX_CRTC];
> +	struct mtk_drm_private *temp_drm_priv;
>   	struct device_node *phandle = dev->parent->of_node;
>   	const struct of_device_id *of_id;
>   	struct device_node *node;
> @@ -373,9 +374,18 @@ static bool mtk_drm_get_all_drm_priv(struct device *dev)
>   		if (!drm_dev || !dev_get_drvdata(drm_dev))
>   			continue;
>   
> -		all_drm_priv[cnt] = dev_get_drvdata(drm_dev);
> -		if (all_drm_priv[cnt] && all_drm_priv[cnt]->mtk_drm_bound)
> -			cnt++;
> +		temp_drm_priv = dev_get_drvdata(drm_dev);
> +		if (temp_drm_priv) {

This is inside a 'for' loop right ?
Why don't you just 'continue' if temp_drm_priv is null ?


> +			if (temp_drm_priv->mtk_drm_bound)
> +				cnt++;
> +
> +			if (temp_drm_priv->data->main_len)
> +				all_drm_priv[CRTC_MAIN] = temp_drm_priv;
> +			else if (temp_drm_priv->data->ext_len)
> +				all_drm_priv[CRTC_EXT] = temp_drm_priv;
> +			else if (temp_drm_priv->data->third_len)
> +				all_drm_priv[CRTC_THIRD] = temp_drm_priv;
> +		}
>   	}
>   
>   	if (drm_priv->data->mmsys_dev_num == cnt) {