[PATCH] dma-buf: heaps: remove duplicated cache sync
Christian König
christian.koenig at amd.com
Mon Aug 30 03:16:28 PDT 2021
Am 30.08.21 um 12:01 schrieb guangming.cao at mediatek.com:
> From: Guangming Cao <Guangming.Cao at mediatek.com>
>
> Current flow, one dmabuf maybe call cache sync many times if
> it has beed mapped more than one time.
Well I'm not an expert on DMA heaps, but this will most likely not work
correctly.
> Is there any case that attachments of one dmabuf will points to
> different memory? If not, seems do sync only one time is more better.
I think that this can happen, yes.
Christian.
>
> Signed-off-by: Guangming Cao <Guangming.Cao at mediatek.com>
> ---
> drivers/dma-buf/heaps/system_heap.c | 14 ++++++++------
> 1 file changed, 8 insertions(+), 6 deletions(-)
>
> diff --git a/drivers/dma-buf/heaps/system_heap.c b/drivers/dma-buf/heaps/system_heap.c
> index 23a7e74ef966..909ef652a8c8 100644
> --- a/drivers/dma-buf/heaps/system_heap.c
> +++ b/drivers/dma-buf/heaps/system_heap.c
> @@ -162,9 +162,10 @@ static int system_heap_dma_buf_begin_cpu_access(struct dma_buf *dmabuf,
> invalidate_kernel_vmap_range(buffer->vaddr, buffer->len);
>
> list_for_each_entry(a, &buffer->attachments, list) {
> - if (!a->mapped)
> - continue;
> - dma_sync_sgtable_for_cpu(a->dev, a->table, direction);
> + if (a->mapped) {
> + dma_sync_sgtable_for_cpu(a->dev, a->table, direction);
> + break;
> + }
> }
> mutex_unlock(&buffer->lock);
>
> @@ -183,9 +184,10 @@ static int system_heap_dma_buf_end_cpu_access(struct dma_buf *dmabuf,
> flush_kernel_vmap_range(buffer->vaddr, buffer->len);
>
> list_for_each_entry(a, &buffer->attachments, list) {
> - if (!a->mapped)
> - continue;
> - dma_sync_sgtable_for_device(a->dev, a->table, direction);
> + if (!a->mapped) {
> + dma_sync_sgtable_for_device(a->dev, a->table, direction);
> + break;
> + }
> }
> mutex_unlock(&buffer->lock);
>
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