Don't BUG out if the link reports an invalid (or plain unknown) bandwidth value, but report the failure and fail gracefully.
Fixes a trivial compiler warning in case the BUG is ever compiled away. Link: http://lkml.kernel.org/p/1415785566-12758-1-git-send-email-geert at linux-m68k.org Signed-off-by: Chris Wilson <chris at chris-wilson.co.uk> Cc: Dave Airlie <airlied at redhat.com> --- drivers/gpu/drm/drm_dp_mst_topology.c | 28 ++++++++++++++++++++++------ 1 file changed, 22 insertions(+), 6 deletions(-) diff --git a/drivers/gpu/drm/drm_dp_mst_topology.c b/drivers/gpu/drm/drm_dp_mst_topology.c index dc98b8f78168..5682d7e9f1ec 100644 --- a/drivers/gpu/drm/drm_dp_mst_topology.c +++ b/drivers/gpu/drm/drm_dp_mst_topology.c @@ -1799,17 +1799,27 @@ static int drm_dp_send_up_ack_reply(struct drm_dp_mst_topology_mgr *mgr, return 0; } -static int drm_dp_get_vc_payload_bw(int dp_link_bw, int dp_link_count) +static bool drm_dp_get_vc_payload_bw(int dp_link_bw, + int dp_link_count, + int *out) { switch (dp_link_bw) { + default: + DRM_DEBUG_KMS("invalid link bandwidth in DPCD: %x (link count: %d)\n", + dp_link_bw, dp_link_count); + return false; + case DP_LINK_BW_1_62: - return 3 * dp_link_count; + *out = 3 * dp_link_count; + break; case DP_LINK_BW_2_7: - return 5 * dp_link_count; + *out = 5 * dp_link_count; + break; case DP_LINK_BW_5_4: - return 10 * dp_link_count; + *out = 10 * dp_link_count; + break; } - BUG(); + return true; } /** @@ -1841,7 +1851,13 @@ int drm_dp_mst_topology_mgr_set_mst(struct drm_dp_mst_topology_mgr *mgr, bool ms goto out_unlock; } - mgr->pbn_div = drm_dp_get_vc_payload_bw(mgr->dpcd[1], mgr->dpcd[2] & DP_MAX_LANE_COUNT_MASK); + if (!drm_dp_get_vc_payload_bw(mgr->dpcd[1], + mgr->dpcd[2] & DP_MAX_LANE_COUNT_MASK, + &mgr->pbn_div)) { + ret = -EINVAL; + goto out_unlock; + } + mgr->total_pbn = 2560; mgr->total_slots = DIV_ROUND_UP(mgr->total_pbn, mgr->pbn_div); mgr->avail_slots = mgr->total_slots; -- 2.1.3
