[PATCH 3/7] drm/etnaviv: Don't break exclusive fence ordering

[Daniel Vetter <daniel.vetter@ffwll.ch>]

There's only one exclusive slot, and we must not break the ordering.

A better fix would be to us a dma_fence_chain or _array like e.g.
amdgpu now uses, but it probably makes sense to lift this into
dma-resv.c code as a proper concept, so that drivers don't have to
hack up their own solution each on their own. Hence go with the simple
fix for now.

Another option is the fence import ioctl from Jason:

https://lore.kernel.org/dri-devel/20210610210925.642582-7-jason@jlekstrand.net/

Signed-off-by: Daniel Vetter <daniel.vetter@intel.com>
Cc: Lucas Stach <l.stach@pengutronix.de>
Cc: Russell King <linux+etnaviv@armlinux.org.uk>
Cc: Christian Gmeiner <christian.gmeiner@gmail.com>
Cc: etnaviv@lists.freedesktop.org
---
 drivers/gpu/drm/etnaviv/etnaviv_gem_submit.c | 8 +++++---
 1 file changed, 5 insertions(+), 3 deletions(-)

diff --git a/drivers/gpu/drm/etnaviv/etnaviv_gem_submit.c b/drivers/gpu/drm/etnaviv/etnaviv_gem_submit.c
index 92478a50a580..5c4fed2b7c6a 100644
--- a/drivers/gpu/drm/etnaviv/etnaviv_gem_submit.c
+++ b/drivers/gpu/drm/etnaviv/etnaviv_gem_submit.c
@@ -178,18 +178,20 @@ static int submit_fence_sync(struct etnaviv_gem_submit *submit)
 	for (i = 0; i < submit->nr_bos; i++) {
 		struct etnaviv_gem_submit_bo *bo = &submit->bos[i];
 		struct dma_resv *robj = bo->obj->base.resv;
+		bool write = bo->flags & ETNA_SUBMIT_BO_WRITE;
 
-		if (!(bo->flags & ETNA_SUBMIT_BO_WRITE)) {
+		if (!(write)) {
 			ret = dma_resv_reserve_shared(robj, 1);
 			if (ret)
 				return ret;
 		}
 
-		if (submit->flags & ETNA_SUBMIT_NO_IMPLICIT)
+		/* exclusive fences must be ordered */
+		if (submit->flags & ETNA_SUBMIT_NO_IMPLICIT && !write)
 			continue;
 
 		ret = drm_sched_job_await_implicit(&submit->sched_job, &bo->obj->base,
-						   bo->flags & ETNA_SUBMIT_BO_WRITE);
+						   write);
 		if (ret)
 			return ret;
 	}
-- 
2.32.0