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Message-ID: <c35bef87-df92-148c-cd83-aaf2ee61e644@ti.com>
Date: Fri, 29 Mar 2019 10:19:20 -0500
From: "Andrew F. Davis" <afd@...com>
To: Benjamin Gaignard <benjamin.gaignard@...aro.org>,
John Stultz <john.stultz@...aro.org>
CC: lkml <linux-kernel@...r.kernel.org>,
Laura Abbott <labbott@...hat.com>,
Sumit Semwal <sumit.semwal@...aro.org>,
Liam Mark <lmark@...eaurora.org>,
Pratik Patel <pratikp@...eaurora.org>,
Brian Starkey <Brian.Starkey@....com>,
Vincent Donnefort <Vincent.Donnefort@....com>,
Sudipto Paul <Sudipto.Paul@....com>,
Xu YiPing <xuyiping@...ilicon.com>,
"Chenfeng (puck)" <puck.chen@...ilicon.com>,
butao <butao@...ilicon.com>,
"Xiaqing (A)" <saberlily.xia@...ilicon.com>,
Yudongbin <yudongbin@...ilicon.com>,
Christoph Hellwig <hch@...radead.org>,
Chenbo Feng <fengc@...gle.com>,
Alistair Strachan <astrachan@...gle.com>,
ML dri-devel <dri-devel@...ts.freedesktop.org>
Subject: Re: [RFC][PATCH 4/6 v3] dma-buf: heaps: Add CMA heap to dmabuf heapss
On 3/29/19 9:44 AM, Benjamin Gaignard wrote:
> Le ven. 29 mars 2019 à 01:16, John Stultz <john.stultz@...aro.org> a écrit :
>>
>> This adds a CMA heap, which allows userspace to allocate
>> a dma-buf of contiguous memory out of a CMA region.
>>
>> This code is an evolution of the Android ION implementation, so
>> thanks to its original author and maintainters:
>> Benjamin Gaignard, Laura Abbott, and others!
>>
>> Cc: Laura Abbott <labbott@...hat.com>
>> Cc: Benjamin Gaignard <benjamin.gaignard@...aro.org>
>> Cc: Sumit Semwal <sumit.semwal@...aro.org>
>> Cc: Liam Mark <lmark@...eaurora.org>
>> Cc: Pratik Patel <pratikp@...eaurora.org>
>> Cc: Brian Starkey <Brian.Starkey@....com>
>> Cc: Vincent Donnefort <Vincent.Donnefort@....com>
>> Cc: Sudipto Paul <Sudipto.Paul@....com>
>> Cc: Andrew F. Davis <afd@...com>
>> Cc: Xu YiPing <xuyiping@...ilicon.com>
>> Cc: "Chenfeng (puck)" <puck.chen@...ilicon.com>
>> Cc: butao <butao@...ilicon.com>
>> Cc: "Xiaqing (A)" <saberlily.xia@...ilicon.com>
>> Cc: Yudongbin <yudongbin@...ilicon.com>
>> Cc: Christoph Hellwig <hch@...radead.org>
>> Cc: Chenbo Feng <fengc@...gle.com>
>> Cc: Alistair Strachan <astrachan@...gle.com>
>> Cc: dri-devel@...ts.freedesktop.org
>> Signed-off-by: John Stultz <john.stultz@...aro.org>
>> ---
>> v2:
>> * Switch allocate to return dmabuf fd
>> * Simplify init code
>> * Checkpatch fixups
>> v3:
>> * Switch to inline function for to_cma_heap()
>> * Minor cleanups suggested by Brian
>> * Fold in new registration style from Andrew
>> * Folded in changes from Andrew to use simplified page list
>> from the heap helpers
>> ---
>> drivers/dma-buf/heaps/Kconfig | 8 ++
>> drivers/dma-buf/heaps/Makefile | 1 +
>> drivers/dma-buf/heaps/cma_heap.c | 170 +++++++++++++++++++++++++++++++++++++++
>> 3 files changed, 179 insertions(+)
>> create mode 100644 drivers/dma-buf/heaps/cma_heap.c
>>
>> diff --git a/drivers/dma-buf/heaps/Kconfig b/drivers/dma-buf/heaps/Kconfig
>> index 2050527..a5eef06 100644
>> --- a/drivers/dma-buf/heaps/Kconfig
>> +++ b/drivers/dma-buf/heaps/Kconfig
>> @@ -4,3 +4,11 @@ config DMABUF_HEAPS_SYSTEM
>> help
>> Choose this option to enable the system dmabuf heap. The system heap
>> is backed by pages from the buddy allocator. If in doubt, say Y.
>> +
>> +config DMABUF_HEAPS_CMA
>> + bool "DMA-BUF CMA Heap"
>> + depends on DMABUF_HEAPS && DMA_CMA
>> + help
>> + 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.
>> diff --git a/drivers/dma-buf/heaps/Makefile b/drivers/dma-buf/heaps/Makefile
>> index d1808ec..6e54cde 100644
>> --- a/drivers/dma-buf/heaps/Makefile
>> +++ b/drivers/dma-buf/heaps/Makefile
>> @@ -1,3 +1,4 @@
>> # SPDX-License-Identifier: GPL-2.0
>> obj-y += heap-helpers.o
>> obj-$(CONFIG_DMABUF_HEAPS_SYSTEM) += system_heap.o
>> +obj-$(CONFIG_DMABUF_HEAPS_CMA) += cma_heap.o
>> diff --git a/drivers/dma-buf/heaps/cma_heap.c b/drivers/dma-buf/heaps/cma_heap.c
>> new file mode 100644
>> index 0000000..f4485c60
>> --- /dev/null
>> +++ b/drivers/dma-buf/heaps/cma_heap.c
>> @@ -0,0 +1,170 @@
>> +// SPDX-License-Identifier: GPL-2.0
>> +/*
>> + * DMABUF CMA heap exporter
>> + *
>> + * Copyright (C) 2012, 2019 Linaro Ltd.
>> + * Author: <benjamin.gaignard@...aro.org> for ST-Ericsson.
>> + */
>> +
>> +#include <linux/device.h>
>> +#include <linux/dma-buf.h>
>> +#include <linux/dma-heap.h>
>> +#include <linux/slab.h>
>> +#include <linux/errno.h>
>> +#include <linux/err.h>
>> +#include <linux/cma.h>
>> +#include <linux/scatterlist.h>
>> +#include <linux/highmem.h>
>> +
>> +#include "heap-helpers.h"
>> +
>> +struct cma_heap {
>> + struct dma_heap *heap;
>> + struct cma *cma;
>> +};
>> +
>> +static void cma_heap_free(struct heap_helper_buffer *buffer)
>> +{
>> + struct cma_heap *cma_heap = dma_heap_get_data(buffer->heap_buffer.heap);
>> + struct page *pages = buffer->priv_virt;
>> + unsigned long nr_pages;
>> +
>> + nr_pages = buffer->heap_buffer.size >> PAGE_SHIFT;
>> +
>> + /* free page list */
>> + kfree(buffer->pages);
>> + /* release memory */
>> + cma_release(cma_heap->cma, pages, nr_pages);
>> + kfree(buffer);
>> +}
>> +
>> +/* dmabuf heap CMA operations functions */
>> +static int cma_heap_allocate(struct dma_heap *heap,
>> + unsigned long len,
>> + unsigned long flags)
>> +{
>> + struct cma_heap *cma_heap = dma_heap_get_data(heap);
>> + struct heap_helper_buffer *helper_buffer;
>> + struct page *pages;
>> + size_t size = PAGE_ALIGN(len);
>> + unsigned long nr_pages = size >> PAGE_SHIFT;
>> + unsigned long align = get_order(size);
>> + DEFINE_DMA_BUF_EXPORT_INFO(exp_info);
>> + struct dma_buf *dmabuf;
>> + int ret = -ENOMEM;
>> + pgoff_t pg;
>> +
>> + if (align > CONFIG_CMA_ALIGNMENT)
>> + align = CONFIG_CMA_ALIGNMENT;
>> +
>> + helper_buffer = kzalloc(sizeof(*helper_buffer), GFP_KERNEL);
>> + if (!helper_buffer)
>> + return -ENOMEM;
>> +
>> + INIT_HEAP_HELPER_BUFFER(helper_buffer, cma_heap_free);
>> + helper_buffer->heap_buffer.flags = flags;
>> + helper_buffer->heap_buffer.heap = heap;
>> + helper_buffer->heap_buffer.size = len;
>> +
>> + pages = cma_alloc(cma_heap->cma, nr_pages, align, false);
>> + if (!pages)
>> + goto free_buf;
>> +
>> + if (PageHighMem(pages)) {
>> + unsigned long nr_clear_pages = nr_pages;
>> + struct page *page = pages;
>> +
>> + while (nr_clear_pages > 0) {
>> + void *vaddr = kmap_atomic(page);
>> +
>> + memset(vaddr, 0, PAGE_SIZE);
>> + kunmap_atomic(vaddr);
>> + page++;
>> + nr_clear_pages--;
>> + }
>> + } else {
>> + memset(page_address(pages), 0, size);
>> + }
>> +
>> + helper_buffer->pagecount = nr_pages;
>> + helper_buffer->pages = kmalloc_array(helper_buffer->pagecount,
>> + sizeof(*helper_buffer->pages),
>> + GFP_KERNEL);
>> + if (!helper_buffer->pages) {
>> + ret = -ENOMEM;
>> + goto free_cma;
>> + }
>> +
>> + for (pg = 0; pg < helper_buffer->pagecount; pg++) {
>> + helper_buffer->pages[pg] = &pages[pg];
>> + if (!helper_buffer->pages[pg])
>> + goto free_pages;
>> + }
>> +
>> + /* create the dmabuf */
>> + exp_info.ops = &heap_helper_ops;
>> + exp_info.size = len;
>> + exp_info.flags = O_RDWR;
>
> I think that the flags should be provided when requesting the allocation
> like it is done in DRM or V4L2.
> For me DMA_HEAP_VALID_FLAGS = (O_CLOEXEC | O_ACCMODE).
>
So something like done in udmabuf?
https://elixir.bootlin.com/linux/v5.1-rc1/source/include/uapi/linux/udmabuf.h#L8
I think that can be arranged.
John,
This might be a good reason to move the dma_buf_fd() call below out of
the heap and back into the core. That way the file exporting flags can
be common and core handled. I don't think it would complicate the error
handling any as we only need to dma_buf_put(dmabuf) in the core on
failure and the heap specific cleanup will happen for us.
Andrew
> Benjamin
>
> Benjamin
>
>> + exp_info.priv = &helper_buffer->heap_buffer;
>> + dmabuf = dma_buf_export(&exp_info);
>> + if (IS_ERR(dmabuf)) {
>> + ret = PTR_ERR(dmabuf);
>> + goto free_pages;
>> + }
>> +
>> + helper_buffer->heap_buffer.dmabuf = dmabuf;
>> + helper_buffer->priv_virt = pages;
>> +
>> + ret = dma_buf_fd(dmabuf, O_CLOEXEC);
>> + if (ret < 0) {
>> + dma_buf_put(dmabuf);
>> + /* just return, as put will call release and that will free */
>> + return ret;
>> + }
>> +
>> + return ret;
>> +
>> +free_pages:
>> + kfree(helper_buffer->pages);
>> +free_cma:
>> + cma_release(cma_heap->cma, pages, nr_pages);
>> +free_buf:
>> + kfree(helper_buffer);
>> + return ret;
>> +}
>> +
>> +static struct dma_heap_ops cma_heap_ops = {
>> + .allocate = cma_heap_allocate,
>> +};
>> +
>> +static int __add_cma_heap(struct cma *cma, void *data)
>> +{
>> + struct cma_heap *cma_heap;
>> + struct dma_heap_export_info exp_info;
>> +
>> + cma_heap = kzalloc(sizeof(*cma_heap), GFP_KERNEL);
>> + if (!cma_heap)
>> + return -ENOMEM;
>> + cma_heap->cma = cma;
>> +
>> + exp_info.name = cma_get_name(cma);
>> + exp_info.ops = &cma_heap_ops;
>> + exp_info.priv = cma_heap;
>> +
>> + cma_heap->heap = dma_heap_add(&exp_info);
>> + if (IS_ERR(cma_heap->heap)) {
>> + int ret = PTR_ERR(cma_heap->heap);
>> +
>> + kfree(cma_heap);
>> + return ret;
>> + }
>> +
>> + return 0;
>> +}
>> +
>> +static int add_cma_heaps(void)
>> +{
>> + cma_for_each_area(__add_cma_heap, NULL);
>> + return 0;
>> +}
>> +device_initcall(add_cma_heaps);
>> --
>> 2.7.4
>>
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