From 4e6242598d1f840d6d2825f4ed98c955964c664e Mon Sep 17 00:00:00 2001 From: Rajkumar Subbiah Date: Wed, 15 Sep 2021 16:59:49 -0400 Subject: [PATCH] UPSTREAM: drm/dp_mst: Fix return code on sideband message failure Commit 2f015ec6eab6 ("drm/dp_mst: Add sideband down request tracing + selftests") added some debug code for sideband message tracing. But it seems to have unintentionally changed the behavior on sideband message failure. It catches and returns failure only if DRM_UT_DP is enabled. Otherwise it ignores the error code and returns success. So on an MST unplug, the caller is unaware that the clear payload message failed and ends up waiting for 4 seconds for the response. Fixes the issue by returning the proper error code. Changes in V2: -- Revise commit text as review comment -- add Fixes text Changes in V3: -- remove "unlikely" optimization Fixes: 2f015ec6eab6 ("drm/dp_mst: Add sideband down request tracing + selftests") Change-Id: Id45a9308d05134e4874144782e31bd92c7f9faae (cherry picked from commit bb693c114e8b53e3e0b8228be218d907d35959a5) Cc: # v5.5+ Signed-off-by: Rajkumar Subbiah Signed-off-by: Kuogee Hsieh Reviewed-by: Stephen Boyd Reviewed-by: Jani Nikula Reviewed-by: Lyude Paul Signed-off-by: Lyude Paul Link: https://patchwork.freedesktop.org/patch/msgid/1625585434-9562-1-git-send-email-khsieh@codeaurora.org --- drivers/gpu/drm/drm_dp_mst_topology.c | 10 ++++++---- 1 file changed, 6 insertions(+), 4 deletions(-) diff --git a/drivers/gpu/drm/drm_dp_mst_topology.c b/drivers/gpu/drm/drm_dp_mst_topology.c index a08cc6b53bc2..4478511c38f7 100644 --- a/drivers/gpu/drm/drm_dp_mst_topology.c +++ b/drivers/gpu/drm/drm_dp_mst_topology.c @@ -2889,11 +2889,13 @@ static int process_single_tx_qlock(struct drm_dp_mst_topology_mgr *mgr, idx += tosend + 1; ret = drm_dp_send_sideband_msg(mgr, up, chunk, idx); - if (unlikely(ret) && drm_debug_enabled(DRM_UT_DP)) { - struct drm_printer p = drm_debug_printer(DBG_PREFIX); + if (ret) { + if (drm_debug_enabled(DRM_UT_DP)) { + struct drm_printer p = drm_debug_printer(DBG_PREFIX); - drm_printf(&p, "sideband msg failed to send\n"); - drm_dp_mst_dump_sideband_msg_tx(&p, txmsg); + drm_printf(&p, "sideband msg failed to send\n"); + drm_dp_mst_dump_sideband_msg_tx(&p, txmsg); + } return ret; }