linux-kernel - Re: [RFC][PATCH 2/4] mm: cma: Add dma

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Message-ID: <20200501104810.v6oa2yhawr4iki67@DESKTOP-E1NTVVP.localdomain>
Date:   Fri, 1 May 2020 11:48:10 +0100
From:   Brian Starkey <brian.starkey@....com>
To:     John Stultz <john.stultz@...aro.org>
Cc:     lkml <linux-kernel@...r.kernel.org>,
        Rob Herring <robh+dt@...nel.org>,
        Sumit Semwal <sumit.semwal@...aro.org>,
        "Andrew F. Davis" <afd@...com>,
        Benjamin Gaignard <benjamin.gaignard@...aro.org>,
        Liam Mark <lmark@...eaurora.org>,
        Pratik Patel <pratikp@...eaurora.org>,
        Laura Abbott <labbott@...hat.com>,
        Chenbo Feng <fengc@...gle.com>,
        Alistair Strachan <astrachan@...gle.com>,
        Sandeep Patil <sspatil@...gle.com>,
        Hridya Valsaraju <hridya@...gle.com>,
        Christoph Hellwig <hch@....de>,
        Marek Szyprowski <m.szyprowski@...sung.com>,
        Robin Murphy <robin.murphy@....com>,
        Andrew Morton <akpm@...ux-foundation.org>,
        devicetree@...r.kernel.org, dri-devel@...ts.freedesktop.org,
        linux-mm@...ck.org, nd@....com
Subject: Re: [RFC][PATCH 2/4] mm: cma: Add dma_heap flag to cma structure

On Fri, May 01, 2020 at 07:39:47AM +0000, John Stultz wrote:
> This patch adds a dma_heap flag on the cma structure,
> along with accessors to set and read the flag.
> 
> This is then used to process and store the "linux,cma-heap"
> property documented in the previous patch.
> 
> Cc: Rob Herring <robh+dt@...nel.org>
> Cc: Sumit Semwal <sumit.semwal@...aro.org>
> Cc: "Andrew F. Davis" <afd@...com>
> Cc: Benjamin Gaignard <benjamin.gaignard@...aro.org>
> Cc: Liam Mark <lmark@...eaurora.org>
> Cc: Pratik Patel <pratikp@...eaurora.org>
> Cc: Laura Abbott <labbott@...hat.com>
> Cc: Brian Starkey <Brian.Starkey@....com>
> Cc: Chenbo Feng <fengc@...gle.com>
> Cc: Alistair Strachan <astrachan@...gle.com>
> Cc: Sandeep Patil <sspatil@...gle.com>
> Cc: Hridya Valsaraju <hridya@...gle.com>
> Cc: Christoph Hellwig <hch@....de>
> Cc: Marek Szyprowski <m.szyprowski@...sung.com>
> Cc: Robin Murphy <robin.murphy@....com>
> Cc: Andrew Morton <akpm@...ux-foundation.org>
> Cc: devicetree@...r.kernel.org
> Cc: dri-devel@...ts.freedesktop.org
> Cc: linux-mm@...ck.org
> Signed-off-by: John Stultz <john.stultz@...aro.org>
> ---
>  include/linux/cma.h     |  3 +++
>  kernel/dma/contiguous.c |  3 +++
>  mm/cma.c                | 11 +++++++++++
>  mm/cma.h                |  1 +
>  4 files changed, 18 insertions(+)
> 
> diff --git a/include/linux/cma.h b/include/linux/cma.h
> index 6ff79fefd01f..d8b8e6ce221c 100644
> --- a/include/linux/cma.h
> +++ b/include/linux/cma.h
> @@ -25,6 +25,9 @@ extern phys_addr_t cma_get_base(const struct cma *cma);
>  extern unsigned long cma_get_size(const struct cma *cma);
>  extern const char *cma_get_name(const struct cma *cma);
>  
> +extern void __init cma_enable_dma_heap(struct cma *cma, bool enabled);
> +extern bool cma_dma_heap_enabled(struct cma *cma);
> +
>  extern int __init cma_declare_contiguous_nid(phys_addr_t base,
>  			phys_addr_t size, phys_addr_t limit,
>  			phys_addr_t alignment, unsigned int order_per_bit,
> diff --git a/kernel/dma/contiguous.c b/kernel/dma/contiguous.c
> index 8bc6f2d670f9..f667fd51daa2 100644
> --- a/kernel/dma/contiguous.c
> +++ b/kernel/dma/contiguous.c
> @@ -303,6 +303,7 @@ static int __init rmem_cma_setup(struct reserved_mem *rmem)
>  	phys_addr_t mask = align - 1;
>  	unsigned long node = rmem->fdt_node;
>  	bool default_cma = of_get_flat_dt_prop(node, "linux,cma-default", NULL);
> +	bool heap_exported = of_get_flat_dt_prop(node, "linux,cma-heap", NULL);
>  	struct cma *cma;
>  	int err;
>  
> @@ -332,6 +333,8 @@ static int __init rmem_cma_setup(struct reserved_mem *rmem)
>  	if (default_cma)
>  		dma_contiguous_set_default(cma);
>  
> +	cma_enable_dma_heap(cma, heap_exported);
> +
>  	rmem->ops = &rmem_cma_ops;
>  	rmem->priv = cma;
>  
> diff --git a/mm/cma.c b/mm/cma.c
> index 0463ad2ce06b..ec671bd8f66e 100644
> --- a/mm/cma.c
> +++ b/mm/cma.c
> @@ -55,6 +55,16 @@ const char *cma_get_name(const struct cma *cma)
>  	return cma->name ? cma->name : "(undefined)";
>  }
>  
> +void __init cma_enable_dma_heap(struct cma *cma, bool enabled)
> +{
> +	cma->dma_heap = enabled;
> +}
> +
> +bool cma_dma_heap_enabled(struct cma *cma)
> +{
> +	return !!cma->dma_heap;

Stylistic thing, but I don't think the !! is really necessary. It's
already a bool anyway.

> +}
> +
>  static unsigned long cma_bitmap_aligned_mask(const struct cma *cma,
>  					     unsigned int align_order)
>  {
> @@ -157,6 +167,7 @@ static int __init cma_init_reserved_areas(void)
>  }
>  core_initcall(cma_init_reserved_areas);
>  
> +

nit: spurious newline

Cheers,
-Brian

>  /**
>   * cma_init_reserved_mem() - create custom contiguous area from reserved memory
>   * @base: Base address of the reserved area
> diff --git a/mm/cma.h b/mm/cma.h
> index 33c0b517733c..6fe2242c724f 100644
> --- a/mm/cma.h
> +++ b/mm/cma.h
> @@ -13,6 +13,7 @@ struct cma {
>  	spinlock_t mem_head_lock;
>  #endif
>  	const char *name;
> +	bool dma_heap;
>  };
>  
>  extern struct cma cma_areas[MAX_CMA_AREAS];
> -- 
> 2.17.1
>