linux-kernel - Re: [PATCH 05/11] of: Ratify of_dma

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Message-ID: <20190930125752.GD12051@infradead.org>
Date:   Mon, 30 Sep 2019 05:57:52 -0700
From:   Christoph Hellwig <hch@...radead.org>
To:     Rob Herring <robh@...nel.org>
Cc:     devicetree@...r.kernel.org, linux-arm-kernel@...ts.infradead.org,
        Florian Fainelli <f.fainelli@...il.com>,
        Arnd Bergmann <arnd@...db.de>,
        Frank Rowand <frowand.list@...il.com>,
        linux-pci@...r.kernel.org, linux-kernel@...r.kernel.org,
        Marek Vasut <marek.vasut@...il.com>,
        Lorenzo Pieralisi <lorenzo.pieralisi@....com>,
        Oza Pawandeep <oza.oza@...adcom.com>,
        Stefan Wahren <wahrenst@....net>,
        Simon Horman <horms+renesas@...ge.net.au>,
        Geert Uytterhoeven <geert+renesas@...der.be>,
        Robin Murphy <robin.murphy@....com>,
        Nicolas Saenz Julienne <nsaenzjulienne@...e.de>
Subject: Re: [PATCH 05/11] of: Ratify of_dma_configure() interface

On Thu, Sep 26, 2019 at 07:24:49PM -0500, Rob Herring wrote:
> -int of_dma_configure(struct device *dev, struct device_node *np, bool force_dma)
> +int of_dma_configure(struct device *dev, struct device_node *parent, bool force_dma)

This creates a > 80 char line.

>  {
>  	u64 dma_addr, paddr, size = 0;
>  	int ret;
>  	bool coherent;
>  	unsigned long offset;
>  	const struct iommu_ops *iommu;
> +	struct device_node *np;
>  	u64 mask;
>  
> +	np = dev->of_node;
> +	if (!np)
> +		np = parent;
> +	if (!np)
> +		return -ENODEV;

I have to say I find the older calling convention simpler to understand.
If we want to enforce the invariant I'd rather do that explicitly:

	if (dev->of_node && np != dev->of_node)
		return -EINVAL;