drm/dp_mst: Correct the bug in drm_dp_update_payload_part1()

[Why]
If the payload_state is DP_PAYLOAD_DELETE_LOCAL in series, current
code doesn't delete the payload at current index and just move the
index to next one after shuffling payloads.

[How]
Drop the i++ increasing part in for loop head and decide whether
to increase the index or not according to payload_state of current
payload.

Changes since v1:
* Refine the code to have it easy reading
* Amend the commit message to meet the way code is modified now.

Signed-off-by: Wayne Lin <Wayne.Lin@amd.com>
Reviewed-by: Lyude Paul <lyude@redhat.com>
Fixes: 706246c761dd ("drm/dp_mst: Refactor drm_dp_update_payload_part1()")
Cc: Daniel Vetter <daniel.vetter@ffwll.ch>
Cc: Juston Li <juston.li@intel.com>
Cc: Maarten Lankhorst <maarten.lankhorst@linux.intel.com>
Cc: Maxime Ripard <mripard@kernel.org>
Cc: Sean Paul <sean@poorly.run>
Cc: David Airlie <airlied@linux.ie>
Cc: Daniel Vetter <daniel@ffwll.ch>
Cc: dri-devel@lists.freedesktop.org
Cc: <stable@vger.kernel.org> # v5.1+
[Added cc for stable]
Signed-off-by: Lyude Paul <lyude@redhat.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20191203042423.5961-1-Wayne.Lin@amd.com

diff --git a/drivers/gpu/drm/drm_dp_mst_topology.c b/drivers/gpu/drm/drm_dp_mst_topology.c
index ae5809a..273dd80 100644 (file)
--- a/drivers/gpu/drm/drm_dp_mst_topology.c
+++ b/drivers/gpu/drm/drm_dp_mst_topology.c
@@ -3176,9 +3176,11 @@ int drm_dp_update_payload_part1(struct drm_dp_mst_topology_mgr *mgr)
                        drm_dp_mst_topology_put_port(port);
        }
 
-       for (i = 0; i < mgr->max_payloads; i++) {
-               if (mgr->payloads[i].payload_state != DP_PAYLOAD_DELETE_LOCAL)
+       for (i = 0; i < mgr->max_payloads; /* do nothing */) {
+               if (mgr->payloads[i].payload_state != DP_PAYLOAD_DELETE_LOCAL) {
+                       i++;
                        continue;
+               }
 
                DRM_DEBUG_KMS("removing payload %d\n", i);
                for (j = i; j < mgr->max_payloads - 1; j++) {