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Message-ID: <9e5b1d16-bfb8-dc89-beda-94a641be793d@xs4all.nl>
Date: Tue, 3 Aug 2021 10:39:06 +0200
From: Hans Verkuil <hverkuil-cisco@...all.nl>
To: Sergey Senozhatsky <senozhatsky@...omium.org>,
Tomasz Figa <tfiga@...omium.org>
Cc: Dafna Hirschfeld <dafna.hirschfeld@...labora.com>,
Ricardo Ribalda <ribalda@...omium.org>,
Christoph Hellwig <hch@....de>,
Mauro Carvalho Chehab <mchehab@...nel.org>,
linux-media@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCHv4 8/8] videobuf2: handle non-contiguous DMA allocations
On 03/08/2021 10:33, Hans Verkuil wrote:
> On 27/07/2021 09:05, Sergey Senozhatsky wrote:
>> This adds support for new noncontiguous DMA API, which
>
> for -> for the
>
>> requires allocators to have two execution branches: one
>> for the current API, and one for the new one.
>>
>> Signed-off-by: Sergey Senozhatsky <senozhatsky@...omium.org>
>> Acked-by: Christoph Hellwig <hch@....de>
>> ---
>> .../common/videobuf2/videobuf2-dma-contig.c | 142 +++++++++++++++---
>> 1 file changed, 117 insertions(+), 25 deletions(-)
>>
>> diff --git a/drivers/media/common/videobuf2/videobuf2-dma-contig.c b/drivers/media/common/videobuf2/videobuf2-dma-contig.c
>> index 1e218bc440c6..10f73e27d694 100644
>> --- a/drivers/media/common/videobuf2/videobuf2-dma-contig.c
>> +++ b/drivers/media/common/videobuf2/videobuf2-dma-contig.c
>> @@ -17,6 +17,7 @@
>> #include <linux/sched.h>
>> #include <linux/slab.h>
>> #include <linux/dma-mapping.h>
>> +#include <linux/highmem.h>
>>
>> #include <media/videobuf2-v4l2.h>
>> #include <media/videobuf2-dma-contig.h>
>> @@ -42,6 +43,7 @@ struct vb2_dc_buf {
>> struct dma_buf_attachment *db_attach;
>>
>> struct vb2_buffer *vb;
>> + bool coherent_mem;
>
> I think that this as well should be renamed to non_coherent_mem.
>
>> };
>>
>> /*********************************************/
>> @@ -78,14 +80,22 @@ static void *vb2_dc_cookie(struct vb2_buffer *vb, void *buf_priv)
>> static void *vb2_dc_vaddr(struct vb2_buffer *vb, void *buf_priv)
>> {
>> struct vb2_dc_buf *buf = buf_priv;
>> - struct dma_buf_map map;
>> - int ret;
>>
>> - if (!buf->vaddr && buf->db_attach) {
>> - ret = dma_buf_vmap(buf->db_attach->dmabuf, &map);
>> - buf->vaddr = ret ? NULL : map.vaddr;
>> + if (buf->vaddr)
>> + return buf->vaddr;
>> +
>> + if (buf->db_attach) {
>> + struct dma_buf_map map;
>> +
>> + if (!dma_buf_vmap(buf->db_attach->dmabuf, &map))
>> + buf->vaddr = map.vaddr;
>> +
>> + return buf->vaddr;
>> }
>>
>> + if (!buf->coherent_mem)
>> + buf->vaddr = dma_vmap_noncontiguous(buf->dev, buf->size,
>> + buf->dma_sgt);
>> return buf->vaddr;
>> }
>>
>> @@ -101,13 +111,26 @@ static void vb2_dc_prepare(void *buf_priv)
>> struct vb2_dc_buf *buf = buf_priv;
>> struct sg_table *sgt = buf->dma_sgt;
>>
>> + /* This takes care of DMABUF and user-enforced cache sync hint */
>> if (buf->vb->skip_cache_sync_on_prepare)
>> return;
>>
>> + /*
>> + * Coherent MMAP buffers do not need to be synced, unlike USERPTR
>> + * and non-coherent MMAP buffers.
>> + */
>> + if (buf->vb->memory == V4L2_MEMORY_MMAP && buf->coherent_mem)
>> + return;
>> +
>> if (!sgt)
>> return;
>>
>> + /* For both USERPTR and non-coherent MMAP */
>> dma_sync_sgtable_for_device(buf->dev, sgt, buf->dma_dir);
>> +
>> + /* Non-coherent MMAP only */
>> + if (!buf->coherent_mem && buf->vaddr)
>> + flush_kernel_vmap_range(buf->vaddr, buf->size);
>> }
>>
>> static void vb2_dc_finish(void *buf_priv)
>> @@ -115,13 +138,26 @@ static void vb2_dc_finish(void *buf_priv)
>> struct vb2_dc_buf *buf = buf_priv;
>> struct sg_table *sgt = buf->dma_sgt;
>>
>> + /* This takes care of DMABUF and user-enforced cache sync hint */
>> if (buf->vb->skip_cache_sync_on_finish)
>> return;
>>
>> + /*
>> + * Coherent MMAP buffers do not need to be synced, unlike USERPTR
>> + * and non-coherent MMAP buffers.
>> + */
>> + if (buf->vb->memory == V4L2_MEMORY_MMAP && buf->coherent_mem)
>> + return;
>> +
>> if (!sgt)
>> return;
>>
>> + /* For both USERPTR and non-coherent MMAP */
>> dma_sync_sgtable_for_cpu(buf->dev, sgt, buf->dma_dir);
>> +
>> + /* Non-coherent MMAP only */
>> + if (!buf->coherent_mem && buf->vaddr)
>> + invalidate_kernel_vmap_range(buf->vaddr, buf->size);
>> }
>>
>> /*********************************************/
>> @@ -139,17 +175,66 @@ static void vb2_dc_put(void *buf_priv)
>> sg_free_table(buf->sgt_base);
>> kfree(buf->sgt_base);
>> }
>> - dma_free_attrs(buf->dev, buf->size, buf->cookie, buf->dma_addr,
>> - buf->attrs);
>> +
>> + if (buf->coherent_mem) {
>> + dma_free_attrs(buf->dev, buf->size, buf->cookie,
>> + buf->dma_addr, buf->attrs);
>> + } else {
>> + if (buf->vaddr)
>> + dma_vunmap_noncontiguous(buf->dev, buf->vaddr);
>> + dma_free_noncontiguous(buf->dev, buf->size,
>> + buf->dma_sgt, buf->dma_dir);
>> + }
>> put_device(buf->dev);
>> kfree(buf);
>> }
>>
>> +static int vb2_dc_alloc_coherent(struct vb2_dc_buf *buf)
>> +{
>> + struct vb2_queue *q = buf->vb->vb2_queue;
>> +
>> + buf->cookie = dma_alloc_attrs(buf->dev,
>> + buf->size,
>> + &buf->dma_addr,
>> + GFP_KERNEL | q->gfp_flags,
>> + buf->attrs);
>> + if (!buf->cookie)
>> + return -ENOMEM;
>> +
>> + if (q->dma_attrs & DMA_ATTR_NO_KERNEL_MAPPING)
>> + return 0;
>> +
>> + buf->vaddr = buf->cookie;
>> + return 0;
>> +}
>> +
>> +static int vb2_dc_alloc_non_coherent(struct vb2_dc_buf *buf)
>> +{
>> + struct vb2_queue *q = buf->vb->vb2_queue;
>> +
>> + buf->dma_sgt = dma_alloc_noncontiguous(buf->dev,
>> + buf->size,
>> + buf->dma_dir,
>> + GFP_KERNEL | q->gfp_flags,
>> + buf->attrs);
>> + if (!buf->dma_sgt)
>> + return -ENOMEM;
>> +
>> + buf->dma_addr = sg_dma_address(buf->dma_sgt->sgl);
>> +
>> + /*
>> + * For requests that need kernel mapping (DMA_ATTR_NO_KERNEL_MAPPING
>> + * bit is cleared) we perform dma_vmap_noncontiguous() in vb2_dc_vadd().
Typo: vb2_dc_vadd -> vb2_dc_vaddr
Regards,
Hans
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