On (20/01/24 11:25), Sergey Senozhatsky wrote:
[..]
>
> > Then, if q->allow_cache_hint is set, then default to a cache sync (cache clean)
> > in the prepare for OUTPUT buffers and a cache sync (cache invalidate) in the
> > finish for CAPTURE buffers.
>
> We alter default cache sync behaviour based both on queue ->memory
> type and queue ->dma_dir. Shall both of those cases depend on
> ->allow_cache_hints, or q->memory can be independent?
>
> static void set_buffer_cache_hints(struct vb2_queue *q,
> struct vb2_buffer *vb,
> struct v4l2_buffer *b)
> {
> if (!q->allow_cache_hints)
> return;
>
> /*
> * DMA exporter should take care of cache syncs, so we can avoid
> * explicit ->prepare()/->finish() syncs. For other ->memory types
> * we always need ->prepare() or/and ->finish() cache sync.
> */
> if (q->memory == VB2_MEMORY_DMABUF) {
> vb->need_cache_sync_on_finish = 0;
> vb->need_cache_sync_on_prepare = 0;
> return;
> }
I personally would prefer this to be above ->allow_cache_hints check,
IOW to be independent. Because we need to skip flush/invalidation for
DMABUF anyway, that's what allocators do in ->prepare() and ->finish()
currently.
-ss
