linux-kernel - Re: [PATCH 2/4] dma-mapping: remove dma

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Date:   Thu, 6 Sep 2018 13:14:23 +0100
From:   Robin Murphy <robin.murphy@....com>
To:     Christoph Hellwig <hch@....de>, iommu@...ts.linux-foundation.org
Cc:     Marek Szyprowski <m.szyprowski@...sung.com>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        linux-arm-kernel@...ts.infradead.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH 2/4] dma-mapping: remove dma_configure

On 27/08/18 09:47, Christoph Hellwig wrote:
> There is no good reason for this indirection given that the method
> always exists.

And indeed with the way it works these days we don't really want 
dma_configure() to look like something which can be called from anywhere.

Reviewed-by: Robin Murphy <robin.murphy@....com>

> Signed-off-by: Christoph Hellwig <hch@....de>
> ---
>   drivers/base/dd.c           |  8 +++++---
>   include/linux/dma-mapping.h |  6 ------
>   kernel/dma/mapping.c        | 10 ----------
>   3 files changed, 5 insertions(+), 19 deletions(-)
> 
> diff --git a/drivers/base/dd.c b/drivers/base/dd.c
> index edfc9f0b1180..65128cf8427c 100644
> --- a/drivers/base/dd.c
> +++ b/drivers/base/dd.c
> @@ -480,9 +480,11 @@ static int really_probe(struct device *dev, struct device_driver *drv)
>   	if (ret)
>   		goto pinctrl_bind_failed;
>   
> -	ret = dma_configure(dev);
> -	if (ret)
> -		goto dma_failed;
> +	if (dev->bus->dma_configure) {
> +		ret = dev->bus->dma_configure(dev);
> +		if (ret)
> +			goto dma_failed;
> +	}
>   
>   	if (driver_sysfs_add(dev)) {
>   		printk(KERN_ERR "%s: driver_sysfs_add(%s) failed\n",
> diff --git a/include/linux/dma-mapping.h b/include/linux/dma-mapping.h
> index 1db6a6b46d0d..1c6c7c09bcf2 100644
> --- a/include/linux/dma-mapping.h
> +++ b/include/linux/dma-mapping.h
> @@ -754,14 +754,8 @@ dma_mark_declared_memory_occupied(struct device *dev,
>   #endif /* CONFIG_HAVE_GENERIC_DMA_COHERENT */
>   
>   #ifdef CONFIG_HAS_DMA
> -int dma_configure(struct device *dev);
>   void dma_deconfigure(struct device *dev);
>   #else
> -static inline int dma_configure(struct device *dev)
> -{
> -	return 0;
> -}
> -
>   static inline void dma_deconfigure(struct device *dev) {}
>   #endif
>   
> diff --git a/kernel/dma/mapping.c b/kernel/dma/mapping.c
> index d2a92ddaac4d..25607ceb4a50 100644
> --- a/kernel/dma/mapping.c
> +++ b/kernel/dma/mapping.c
> @@ -328,16 +328,6 @@ void dma_common_free_remap(void *cpu_addr, size_t size, unsigned long vm_flags)
>   }
>   #endif
>   
> -/*
> - * enables DMA API use for a device
> - */
> -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)
>   {
>   	of_dma_deconfigure(dev);
>