drm/etnaviv: add cmdbuf suballocator

There are 3 big benefits to suballocating a single big DMA buffer
for command submission:

1. Avoid hammering CMA. The old way of allocating and freeing a DMA
   buffer for each submission was hitting some of the real slow
   pathes in CMA, as this allocator was not designed for a concurrent
   small buffers load.

2. Less TLB flushes on IOMMUv2. If a new command buffer is mapped into
   the GPU address space the MMU TLBs need to be flushed. By having
   one big buffer statically mapped to the GPU, a lot of those flushes
   can be avoided.

3. No funky workarounds for GC3000. The FE TLB flush on GC3000 isn't
   reliable. To work around that we tried to lay out the cmdbufs in
   the GPU address space in a way to avoid this issue. This hasn't
   always worked if the address space is crowded. A single statically
   mapped buffer avoids the erratum completely.

Signed-off-by: Lucas Stach <l.stach@pengutronix.de>
Reviewed-by: Christian Gmeiner <christian.gmeiner@gmail.com>

1 files changed, 3 insertions, 2 deletions

diff --git a/drivers/gpu/drm/etnaviv/etnaviv_gem_submit.c b/drivers/gpu/drm/etnaviv/etnaviv_gem_submit.c
index 7e1fefef2f2c..726090d7a6ac 100644
--- a/drivers/gpu/drm/etnaviv/etnaviv_gem_submit.c
+++ b/drivers/gpu/drm/etnaviv/etnaviv_gem_submit.c
@@ -333,8 +333,9 @@ int etnaviv_ioctl_gem_submit(struct drm_device *dev, void *data,
 	bos = drm_malloc_ab(args->nr_bos, sizeof(*bos));
 	relocs = drm_malloc_ab(args->nr_relocs, sizeof(*relocs));
 	stream = drm_malloc_ab(1, args->stream_size);
-	cmdbuf = etnaviv_cmdbuf_new(gpu, ALIGN(args->stream_size, 8) + 8,
-					args->nr_bos);
+	cmdbuf = etnaviv_cmdbuf_new(gpu->cmdbuf_suballoc,
+				    ALIGN(args->stream_size, 8) + 8,
+				    args->nr_bos);
 	if (!bos || !relocs || !stream || !cmdbuf) {
 		ret = -ENOMEM;
 		goto err_submit_cmds;