On 18.08.20 10:04, Hyesoo Yu wrote:
> This patch adds support for a chunk heap that allows for buffers
> that are made up of a list of fixed size chunks taken from a CMA.
> Chunk sizes are configuratd when the heaps are created.
>
> Signed-off-by: Hyesoo Yu <hyesoo.yu@xxxxxxxxxxx>
> ---
> drivers/dma-buf/heaps/Kconfig | 9 ++
> drivers/dma-buf/heaps/Makefile | 1 +
> drivers/dma-buf/heaps/chunk_heap.c | 222 +++++++++++++++++++++++++++++++++++++
> 3 files changed, 232 insertions(+)
> create mode 100644 drivers/dma-buf/heaps/chunk_heap.c
>
> diff --git a/drivers/dma-buf/heaps/Kconfig b/drivers/dma-buf/heaps/Kconfig
> index a5eef06..98552fa 100644
> --- a/drivers/dma-buf/heaps/Kconfig
> +++ b/drivers/dma-buf/heaps/Kconfig
> @@ -12,3 +12,12 @@ config DMABUF_HEAPS_CMA
> Choose this option to enable dma-buf CMA heap. This heap is backed
> by the Contiguous Memory Allocator (CMA). If your system has these
> regions, you should say Y here.
> +
> +config DMABUF_HEAPS_CHUNK
> + tristate "DMA-BUF CHUNK Heap"
> + depends on DMABUF_HEAPS && DMA_CMA
> + help
> + Choose this option to enable dma-buf CHUNK heap. This heap is backed
> + by the Contiguous Memory Allocator (CMA) and allocate the buffers that
> + are made up to a list of fixed size chunks tasken from CMA. Chunk sizes
> + are configurated when the heaps are created.
> diff --git a/drivers/dma-buf/heaps/Makefile b/drivers/dma-buf/heaps/Makefile
> index 6e54cde..3b2a0986 100644
> --- a/drivers/dma-buf/heaps/Makefile
> +++ b/drivers/dma-buf/heaps/Makefile
> @@ -2,3 +2,4 @@
> obj-y += heap-helpers.o
> obj-$(CONFIG_DMABUF_HEAPS_SYSTEM) += system_heap.o
> obj-$(CONFIG_DMABUF_HEAPS_CMA) += cma_heap.o
> +obj-$(CONFIG_DMABUF_HEAPS_CHUNK) += chunk_heap.o
> diff --git a/drivers/dma-buf/heaps/chunk_heap.c b/drivers/dma-buf/heaps/chunk_heap.c
> new file mode 100644
> index 0000000..1eefaec
> --- /dev/null
> +++ b/drivers/dma-buf/heaps/chunk_heap.c
> @@ -0,0 +1,222 @@
> +// SPDX-License-Identifier: GPL-2.0
> +/*
> + * ION Memory Allocator chunk heap exporter
> + *
> + * Copyright (c) 2020 Samsung Electronics Co., Ltd.
> + * Author: <hyesoo.yu@xxxxxxxxxxx> for Samsung Electronics.
> + */
> +
> +#include <linux/platform_device.h>
> +#include <linux/cma.h>
> +#include <linux/device.h>
> +#include <linux/dma-buf.h>
> +#include <linux/dma-heap.h>
> +#include <linux/dma-contiguous.h>
> +#include <linux/err.h>
> +#include <linux/errno.h>
> +#include <linux/highmem.h>
> +#include <linux/module.h>
> +#include <linux/slab.h>
> +#include <linux/scatterlist.h>
> +#include <linux/sched/signal.h>
> +#include <linux/of_reserved_mem.h>
> +#include <linux/of.h>
> +
> +#include "heap-helpers.h"
> +
> +struct chunk_heap {
> + struct dma_heap *heap;
> + phys_addr_t base;
> + phys_addr_t size;
> + atomic_t cur_pageblock_idx;
> + unsigned int max_num_pageblocks;
> + unsigned int order;
> +};
> +
> +static void chunk_heap_free(struct heap_helper_buffer *buffer)
> +{
> + struct chunk_heap *chunk_heap = dma_heap_get_drvdata(buffer->heap);
> + pgoff_t pg;
> +
> + for (pg = 0; pg < buffer->pagecount; pg++)
> + __free_pages(buffer->pages[pg], chunk_heap->order);
> + kvfree(buffer->pages);
> + kfree(buffer);
> +}
> +
> +static inline unsigned long chunk_get_next_pfn(struct chunk_heap *chunk_heap)
> +{
> + unsigned long i = atomic_inc_return(&chunk_heap->cur_pageblock_idx) %
> + chunk_heap->max_num_pageblocks;
> +
> + return PHYS_PFN(chunk_heap->base) + i * pageblock_nr_pages;
> +}
> +
> +static int chunk_alloc_pages(struct chunk_heap *chunk_heap, struct page **pages,
> + unsigned int order, unsigned int count)
> +{
> + unsigned long base;
> + unsigned int i = 0, nr_block = 0, nr_elem, ret;
> +
> + while (count) {
> + /*
> + * If the number of scanned page block is the same as max block,
> + * the tries of allocation fails.
> + */
> + if (nr_block++ == chunk_heap->max_num_pageblocks) {
> + ret = -ENOMEM;
> + goto err_bulk;
> + }
> + base = chunk_get_next_pfn(chunk_heap);
> + nr_elem = min_t(unsigned int, count, pageblock_nr_pages >> order);
> + ret = alloc_pages_bulk(base, base + pageblock_nr_pages, MIGRATE_CMA,
> + GFP_KERNEL, order, nr_elem, pages + i);
So you are bypassing the complete cma allocator here. This all smells
like a complete hack to me. No, I don't think this is the right way to
support (or rather speed up allocations for) special, weird hardware.
--
Thanks,
David / dhildenb
