Re: [RFC][PATCH] CMA: drivers/base/Kconfig: restrict CMA size to non-zero value

[Michal Nazarewicz <mina86@mina86.com>]

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On Sun, May 18 2014, Joonsoo Kim wrote:
> I think that this problem is originated from atomic_pool_init().
> If configured coherent_pool size is larger than default cma size,
> it can be failed even if this patch is applied.
>
> How about below patch?
> It uses fallback allocation if CMA is failed.

Yes, I thought about it, but __dma_alloc uses similar code:

	else if (!IS_ENABLED(CONFIG_DMA_CMA))
		addr = __alloc_remap_buffer(dev, size, gfp, prot, &page, caller);
	else
		addr = __alloc_from_contiguous(dev, size, prot, &page, caller);

so it probably needs to be changed as well.

> -----------------8<---------------------
> diff --git a/arch/arm/mm/dma-mapping.c b/arch/arm/mm/dma-mapping.c
> index 6b00be1..2909ab9 100644
> --- a/arch/arm/mm/dma-mapping.c
> +++ b/arch/arm/mm/dma-mapping.c
> @@ -379,7 +379,7 @@ static int __init atomic_pool_init(void)
>         unsigned long *bitmap;
>         struct page *page;
>         struct page **pages;
> -       void *ptr;
> +       void *ptr = NULL;
>         int bitmap_size = BITS_TO_LONGS(nr_pages) * sizeof(long);
>  
>         bitmap = kzalloc(bitmap_size, GFP_KERNEL);
> @@ -393,7 +393,7 @@ static int __init atomic_pool_init(void)
>         if (IS_ENABLED(CONFIG_DMA_CMA))
>                 ptr = __alloc_from_contiguous(NULL, pool->size, prot, &page,
>                                               atomic_pool_init);
> -       else
> +       if (!ptr)
>                 ptr = __alloc_remap_buffer(NULL, pool->size, gfp, prot, &page,
>                                            atomic_pool_init);
>         if (ptr) {
>

-- 
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.o. | Liege of Serenely Enlightened Majesty of      o' \,=./ `o
..o | Computer Science,  Michał “mina86” Nazarewicz    (o o)
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