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From:   Lyude Paul <lyude@redhat.com>
To:     dri-devel@lists.freedesktop.org, nouveau@lists.freedesktop.org
Cc:     Ben Skeggs <bskeggs@redhat.com>, Danilo Krummrich <me@dakr.org>,
        Karol Herbst <kherbst@redhat.com>,
        David Airlie <airlied@gmail.com>,
        Daniel Vetter <daniel@ffwll.ch>, Wayne Lin <Wayne.Lin@amd.com>,
        linux-kernel@vger.kernel.org (open list)
Subject: [PATCH v3 05/44] drm/nouveau/kms/nv50-: fix mst payload alloc fail crashing evo
Date:   Tue, 19 Sep 2023 17:56:00 -0400
Message-ID: <20230919220442.202488-6-lyude@redhat.com>
In-Reply-To: <20230919220442.202488-1-lyude@redhat.com>
References: <20230919220442.202488-1-lyude@redhat.com>
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From: Ben Skeggs <bskeggs@redhat.com>

Programming -1 (vc_start_slot, if alloc fails) into HW probably isn't
the best idea.

Signed-off-by: Ben Skeggs <bskeggs@redhat.com>
Reviewed-by: Lyude Paul <lyude@redhat.com>
Acked-by: Danilo Krummrich <me@dakr.org>
Signed-off-by: Lyude Paul <lyude@redhat.com>
---
 drivers/gpu/drm/nouveau/dispnv50/disp.c | 10 +++++++---
 1 file changed, 7 insertions(+), 3 deletions(-)

diff --git a/drivers/gpu/drm/nouveau/dispnv50/disp.c b/drivers/gpu/drm/nouveau/dispnv50/disp.c
index 39e9ba4139c7d..889ff667d0293 100644
--- a/drivers/gpu/drm/nouveau/dispnv50/disp.c
+++ b/drivers/gpu/drm/nouveau/dispnv50/disp.c
@@ -916,23 +916,27 @@ nv50_msto_prepare(struct drm_atomic_state *state,
 	struct nv50_mstc *mstc = msto->mstc;
 	struct nv50_mstm *mstm = mstc->mstm;
 	struct drm_dp_mst_atomic_payload *payload;
+	int ret = 0;
 
 	NV_ATOMIC(drm, "%s: msto prepare\n", msto->encoder.name);
 
 	payload = drm_atomic_get_mst_payload_state(mst_state, mstc->port);
 
-	// TODO: Figure out if we want to do a better job of handling VCPI allocation failures here?
 	if (msto->disabled) {
 		drm_dp_remove_payload_part1(mgr, mst_state, payload);
-
 		nvif_outp_dp_mst_vcpi(&mstm->outp->outp, msto->head->base.index, 0, 0, 0, 0);
+		ret = 1;
 	} else {
 		if (msto->enabled)
-			drm_dp_add_payload_part1(mgr, mst_state, payload);
+			ret = drm_dp_add_payload_part1(mgr, mst_state, payload);
+	}
 
+	if (ret == 0) {
 		nvif_outp_dp_mst_vcpi(&mstm->outp->outp, msto->head->base.index,
 				      payload->vc_start_slot, payload->time_slots,
 				      payload->pbn, payload->time_slots * mst_state->pbn_div);
+	} else {
+		nvif_outp_dp_mst_vcpi(&mstm->outp->outp, msto->head->base.index, 0, 0, 0, 0);
 	}
 }
 
-- 
2.41.0