linux-kernel - Re: [PATCH 3/3] soc: mediatek: pm-domains: Grab SCPSYS registers from phandle to syscon

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Date:   Tue, 12 Jul 2022 10:39:03 +0200
From:   Krzysztof Kozlowski <krzysztof.kozlowski@...aro.org>
To:     AngeloGioacchino Del Regno 
        <angelogioacchino.delregno@...labora.com>, robh+dt@...nel.org
Cc:     krzysztof.kozlowski+dt@...aro.org, matthias.bgg@...il.com,
        chun-jie.chen@...iatek.com, weiyi.lu@...iatek.com,
        mbrugger@...e.com, devicetree@...r.kernel.org,
        linux-kernel@...r.kernel.org, linux-arm-kernel@...ts.infradead.org,
        linux-mediatek@...ts.infradead.org, kernel@...labora.com,
        nfraprado@...labora.com
Subject: Re: [PATCH 3/3] soc: mediatek: pm-domains: Grab SCPSYS registers from
 phandle to syscon

On 11/07/2022 14:25, AngeloGioacchino Del Regno wrote:
> Instead of requiring nesting of the power-controller inside of a
> "syscon", "simple-mfd" node, look for a phandle to SCPSYS in the
> "syscon" property of the power controller node.
> 
> Compatibility with older devicetrees is retained by falling back
> to looking for a parent node if no syscon phandle is found.
> 
> Signed-off-by: AngeloGioacchino Del Regno <angelogioacchino.delregno@...labora.com>
> ---
>  drivers/soc/mediatek/mtk-pm-domains.c | 16 +++++++++-------
>  1 file changed, 9 insertions(+), 7 deletions(-)
> 
> diff --git a/drivers/soc/mediatek/mtk-pm-domains.c b/drivers/soc/mediatek/mtk-pm-domains.c
> index a3dae391a38a..c5a1c766cd50 100644
> --- a/drivers/soc/mediatek/mtk-pm-domains.c
> +++ b/drivers/soc/mediatek/mtk-pm-domains.c
> @@ -590,8 +590,7 @@ static int scpsys_probe(struct platform_device *pdev)
>  	struct device *dev = &pdev->dev;
>  	struct device_node *np = dev->of_node;
>  	const struct scpsys_soc_data *soc;
> -	struct device_node *node;
> -	struct device *parent;
> +	struct device_node *node, *syscon;
>  	struct scpsys *scpsys;
>  	int ret;
>  
> @@ -611,13 +610,16 @@ static int scpsys_probe(struct platform_device *pdev)
>  	scpsys->pd_data.domains = scpsys->domains;
>  	scpsys->pd_data.num_domains = soc->num_domains;
>  
> -	parent = dev->parent;
> -	if (!parent) {
> -		dev_err(dev, "no parent for syscon devices\n");
> -		return -ENODEV;
> +	syscon = of_parse_phandle(dev->of_node, "syscon", 0);
> +	if (!syscon) {
> +		if (!dev->parent)
> +			return -ENODEV;
> +		scpsys->base = syscon_node_to_regmap(dev->parent->of_node);
> +	} else {
> +		scpsys->base = syscon_node_to_regmap(syscon);
> +		of_node_put(syscon);
>  	}

I responded in previous DTS thread. Technically code looks ok, but it
does not make really sense - either this is a child or a sibling. Not
both for the same hardware!

Best regards,
Krzysztof