linux-kernel - Re: [RFC 2/2] drivers: dma-mapping: parse per device reserved mem at probe time

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Date:   Mon, 27 Nov 2017 09:31:00 +0100
From:   Marek Szyprowski <m.szyprowski@...sung.com>
To:     Peng Fan <peng.fan@....com>, hch@....de, robin.murphy@....com,
        gregkh@...uxfoundation.org, robh+dt@...nel.org,
        frowand.list@...il.com
Cc:     iommu@...ts.linux-foundation.org, linux-kernel@...r.kernel.org,
        devicetree@...r.kernel.org, van.freenix@...il.com
Subject: Re: [RFC 2/2] drivers: dma-mapping: parse per device reserved mem
 at probe time

Hi

On 2017-11-26 14:13, Peng Fan wrote:
> Invoke of_reserved_mem_device_init at dma_configure, then
> there is no need to call of_reserved_mem_device_init in device
> specific probe function.
>
> Signed-off-by: Peng Fan <peng.fan@....com>

This has been already tried long time ago, without success:
http://patches.linaro.org/patch/33558/

> ---
>   drivers/base/dma-mapping.c | 6 +++++-
>   1 file changed, 5 insertions(+), 1 deletion(-)
>
> diff --git a/drivers/base/dma-mapping.c b/drivers/base/dma-mapping.c
> index e584eddef0a7..55dca06a7b55 100644
> --- a/drivers/base/dma-mapping.c
> +++ b/drivers/base/dma-mapping.c
> @@ -12,6 +12,7 @@
>   #include <linux/export.h>
>   #include <linux/gfp.h>
>   #include <linux/of_device.h>
> +#include <linux/of_reserved_mem.h>
>   #include <linux/slab.h>
>   #include <linux/vmalloc.h>
>   
> @@ -351,7 +352,9 @@ int dma_configure(struct device *dev)
>   	}
>   
>   	if (dma_dev->of_node) {
> -		ret = of_dma_configure(dev, dma_dev->of_node);
> +		ret = of_reserved_mem_device_init(dev);
> +		if (ret)
> +			ret = of_dma_configure(dev, dma_dev->of_node);
>   	} else if (has_acpi_companion(dma_dev)) {
>   		attr = acpi_get_dma_attr(to_acpi_device_node(dma_dev->fwnode));
>   		if (attr != DEV_DMA_NOT_SUPPORTED)
> @@ -367,5 +370,6 @@ int dma_configure(struct device *dev)
>   void dma_deconfigure(struct device *dev)
>   {
>   	of_dma_deconfigure(dev);
> +	of_reserved_mem_device_release(dev);
>   	acpi_dma_deconfigure(dev);
>   }

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