linux-kernel - Re: [PATCH] drivers: dma-coherent: simplify dma_init_coherent

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Message-id: <566538E4.30209@samsung.com>
Date:	Mon, 07 Dec 2015 08:44:36 +0100
From:	Marek Szyprowski <m.szyprowski@...sung.com>
To:	Michal Nazarewicz <mina86@...a86.com>,
	Greg Kroah-Hartman <gregkh@...uxfoundation.org>
Cc:	linux-kernel@...r.kernel.org, torvalds@...ux-foundation.org,
	linux-arm-kernel@...ts.infradead.org, arnd@...db.de,
	iamjoonsoo.kim@....com
Subject: Re: [PATCH] drivers: dma-coherent: simplify dma_init_coherent_memory
 return value

Hello,

On 2015-12-04 21:14, Michal Nazarewicz wrote:
> Since only dma_declare_coherent_memory cares about
> dma_init_coherent_memory returning part of flags as it return value,
> move the condition to the former and simplify the latter.  This in
> turn makes rmem_dma_device_init less confusing.
>
> Reported-by: Fugang Duan <B38611@...escale.com>
> Signed-off-by: Michal Nazarewicz <mina86@...a86.com>

Acked-by: Marek Szyprowski <m.szyprowski@...sung.com>

> ---
>   drivers/base/dma-coherent.c | 28 +++++++++++-----------------
>   1 file changed, 11 insertions(+), 17 deletions(-)
>
> diff --git a/drivers/base/dma-coherent.c b/drivers/base/dma-coherent.c
> index 55b8398..87b8083 100644
> --- a/drivers/base/dma-coherent.c
> +++ b/drivers/base/dma-coherent.c
> @@ -17,9 +17,9 @@ struct dma_coherent_mem {
>   	spinlock_t	spinlock;
>   };
>   
> -static int dma_init_coherent_memory(phys_addr_t phys_addr, dma_addr_t device_addr,
> -			     size_t size, int flags,
> -			     struct dma_coherent_mem **mem)
> +static bool dma_init_coherent_memory(
> +	phys_addr_t phys_addr, dma_addr_t device_addr, size_t size, int flags,
> +	struct dma_coherent_mem **mem)
>   {
>   	struct dma_coherent_mem *dma_mem = NULL;
>   	void __iomem *mem_base = NULL;
> @@ -50,17 +50,13 @@ static int dma_init_coherent_memory(phys_addr_t phys_addr, dma_addr_t device_add
>   	spin_lock_init(&dma_mem->spinlock);
>   
>   	*mem = dma_mem;
> -
> -	if (flags & DMA_MEMORY_MAP)
> -		return DMA_MEMORY_MAP;
> -
> -	return DMA_MEMORY_IO;
> +	return true;
>   
>   out:
>   	kfree(dma_mem);
>   	if (mem_base)
>   		iounmap(mem_base);
> -	return 0;
> +	return false;
>   }
>   
>   static void dma_release_coherent_memory(struct dma_coherent_mem *mem)
> @@ -88,15 +84,13 @@ int dma_declare_coherent_memory(struct device *dev, phys_addr_t phys_addr,
>   				dma_addr_t device_addr, size_t size, int flags)
>   {
>   	struct dma_coherent_mem *mem;
> -	int ret;
>   
> -	ret = dma_init_coherent_memory(phys_addr, device_addr, size, flags,
> -				       &mem);
> -	if (ret == 0)
> +	if (!dma_init_coherent_memory(phys_addr, device_addr, size, flags,
> +				      &mem))
>   		return 0;
>   
>   	if (dma_assign_coherent_memory(dev, mem) == 0)
> -		return ret;
> +		return flags & DMA_MEMORY_MAP ? DMA_MEMORY_MAP : DMA_MEMORY_IO;
>   
>   	dma_release_coherent_memory(mem);
>   	return 0;
> @@ -281,9 +275,9 @@ static int rmem_dma_device_init(struct reserved_mem *rmem, struct device *dev)
>   	struct dma_coherent_mem *mem = rmem->priv;
>   
>   	if (!mem &&
> -	    dma_init_coherent_memory(rmem->base, rmem->base, rmem->size,
> -				     DMA_MEMORY_MAP | DMA_MEMORY_EXCLUSIVE,
> -				     &mem) != DMA_MEMORY_MAP) {
> +	    !dma_init_coherent_memory(rmem->base, rmem->base, rmem->size,
> +				      DMA_MEMORY_MAP | DMA_MEMORY_EXCLUSIVE,
> +				      &mem)) {
>   		pr_err("Reserved memory: failed to init DMA memory pool at %pa, size %ld MiB\n",
>   			&rmem->base, (unsigned long)rmem->size / SZ_1M);
>   		return -ENODEV;

Best regards
-- 
Marek Szyprowski, PhD
Samsung R&D Institute Poland

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