From: Guangming Cao <Guangming.Cao@xxxxxxxxxxxx>
> Am 30.08.21 um 12:01 schrieb guangming.cao@xxxxxxxxxxxx:
> > From: Guangming Cao <Guangming.Cao@xxxxxxxxxxxx>
> >
> > 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.
>
All attachments of one dmabuf will add into a list, I think it means dmabuf
supports map more than one time. Could you tell me more about it?
> > 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.
>
Seems it's a very special case on Android, if you don't mind, could you
tell me more about it?
>
> >
> > Signed-off-by: Guangming Cao <Guangming.Cao@xxxxxxxxxxxx>
> > ---
> > 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);
> >
