linux-kernel - Re: [PATCH v2 1/2] dma-mapping: move dma configuration to bus infrastructure

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Message-ID: <20180322081530.GA29444@lst.de>
Date:   Thu, 22 Mar 2018 09:15:30 +0100
From:   Christoph Hellwig <hch@....de>
To:     Nipun Gupta <nipun.gupta@....com>
Cc:     robin.murphy@....com, hch@....de, linux@...linux.org.uk,
        gregkh@...uxfoundation.org, m.szyprowski@...sung.com,
        bhelgaas@...gle.com, zajec5@...il.com, andy.gross@...aro.org,
        david.brown@...aro.org, dan.j.williams@...el.com,
        vinod.koul@...el.com, thierry.reding@...il.com, robh+dt@...nel.org,
        frowand.list@...il.com, jarkko.sakkinen@...ux.intel.com,
        rafael.j.wysocki@...el.com, dmitry.torokhov@...il.com,
        johan@...nel.org, msuchanek@...e.de, linux-kernel@...r.kernel.org,
        iommu@...ts.linux-foundation.org, linux-wireless@...r.kernel.org,
        linux-arm-msm@...r.kernel.org, linux-soc@...r.kernel.org,
        dmaengine@...r.kernel.org, dri-devel@...ts.freedesktop.org,
        linux-tegra@...r.kernel.org, devicetree@...r.kernel.org,
        linux-pci@...r.kernel.org, bharat.bhushan@....com,
        leoyang.li@....com
Subject: Re: [PATCH v2 1/2] dma-mapping: move dma configuration to bus
        infrastructure

> +static int amba_dma_configure(struct device *dev)
> +{
> +	return dma_common_configure(dev);
> +}

So it turns out we only end with two callers of dma_common_configure
after this series.  Based ont hat I'm tempted with the suggestion
from Robin to just have amba call platform_dma_configure, and move
the code from dma_common_configure to platform_dma_configure.

> +int dma_configure(struct device *dev)
> +{
> +	if (dev->bus->dma_configure)
> +		return dev->bus->dma_configure(dev);
> +
> +	return 0;
> +}
>  void dma_deconfigure(struct device *dev)

As grep pointed out this wants a blank line after the function, and while
in nitpicking mode I'd suggest to remove the blank line above the return
statement while at it.

> diff --git a/drivers/gpu/host1x/bus.c b/drivers/gpu/host1x/bus.c
> index 88a3558..fa9896d 100644
> --- a/drivers/gpu/host1x/bus.c
> +++ b/drivers/gpu/host1x/bus.c
> @@ -314,6 +314,14 @@ static int host1x_device_match(struct device *dev, struct device_driver *drv)
>  	return strcmp(dev_name(dev), drv->name) == 0;
>  }
>  
> +static int host1x_dma_configure(struct device *dev)
> +{
> +	if (dev->of_node)
> +		return of_dma_configure(dev, dev->of_node);
> +
> +	return 0;

Same here.

> + */
> +static int pci_dma_configure(struct device *dev)
> +{
> +	struct device *bridge;
> +	enum dev_dma_attr attr;
> +	int ret = 0;
> +
> +	bridge = pci_get_host_bridge_device(to_pci_dev(dev));
> +
> +	if (IS_ENABLED(CONFIG_OF) && bridge->parent &&
> +	    bridge->parent->of_node) {
> +		ret = of_dma_configure(dev, bridge->parent->of_node);
> +	} else if (has_acpi_companion(bridge)) {
> +		attr = acpi_get_dma_attr(to_acpi_device_node(bridge->fwnode));
> +		if (attr != DEV_DMA_NOT_SUPPORTED)
> +			ret = acpi_dma_configure(dev, attr);
> +	}

The attr declaration can be moved into the inner scope here.

> +	pci_put_host_bridge_device(bridge);
> +
> +	return ret;

Drop the blank line after the return, please.