linux-kernel - Re: [PATCH v3, 26/27] drm/mediatek: add clock property check before get it

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Date:   Mon, 17 Jun 2019 11:06:02 +0800
From:   CK Hu <ck.hu@...iatek.com>
To:     <yongqiang.niu@...iatek.com>
CC:     Philipp Zabel <p.zabel@...gutronix.de>,
        Rob Herring <robh+dt@...nel.org>,
        Matthias Brugger <matthias.bgg@...il.com>,
        "David Airlie" <airlied@...ux.ie>, Daniel Vetter <daniel@...ll.ch>,
        Mark Rutland <mark.rutland@....com>,
        <dri-devel@...ts.freedesktop.org>, <devicetree@...r.kernel.org>,
        <linux-kernel@...r.kernel.org>,
        <linux-arm-kernel@...ts.infradead.org>,
        <linux-mediatek@...ts.infradead.org>
Subject: Re: [PATCH v3, 26/27] drm/mediatek: add clock property check before
 get it

Hi, Yongqiang:

On Wed, 2019-06-05 at 19:43 +0800, yongqiang.niu@...iatek.com wrote:
> From: Yongqiang Niu <yongqiang.niu@...iatek.com>
> 
> This patch add clock property check before get it

In the binding document [1], clock is required property. In this patch,
you change it to optional property. I think you should change the
binding document and describe _WHY_ do you do this.

[1]
https://www.kernel.org/doc/Documentation/devicetree/bindings/display/mediatek/mediatek%2Cdisp.txt

Regards,
CK

> 
> Signed-off-by: Yongqiang Niu <yongqiang.niu@...iatek.com>
> ---
>  drivers/gpu/drm/mediatek/mtk_drm_ddp.c | 10 ++++++----
>  1 file changed, 6 insertions(+), 4 deletions(-)
> 
> diff --git a/drivers/gpu/drm/mediatek/mtk_drm_ddp.c b/drivers/gpu/drm/mediatek/mtk_drm_ddp.c
> index 9986c61..28274d2 100644
> --- a/drivers/gpu/drm/mediatek/mtk_drm_ddp.c
> +++ b/drivers/gpu/drm/mediatek/mtk_drm_ddp.c
> @@ -689,10 +689,12 @@ static int mtk_ddp_probe(struct platform_device *pdev)
>  	for (i = 0; i < 10; i++)
>  		ddp->mutex[i].id = i;
>  
> -	ddp->clk = devm_clk_get(dev, NULL);
> -	if (IS_ERR(ddp->clk)) {
> -		dev_err(dev, "Failed to get clock\n");
> -		return PTR_ERR(ddp->clk);
> +	if (of_find_property(dev->of_node, "clocks", &i)) {
> +		ddp->clk = devm_clk_get(dev, NULL);
> +		if (IS_ERR(ddp->clk)) {
> +			dev_err(dev, "Failed to get clock\n");
> +			return PTR_ERR(ddp->clk);
> +		}
>  	}
>  
>  	regs = platform_get_resource(pdev, IORESOURCE_MEM, 0);