From: Simon Ser <contact@emersion.fr> stable inclusion from stable-v5.10.150 commit ad06d6bed5f265ade68123dfd35400a025b29011 category: bugfix bugzilla: https://gitee.com/openeuler/kernel/issues/I6D0XA Reference: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=... -------------------------------- [ Upstream commit 2ac6cdd581f48c8f68747156fde5868486a44985 ] drm_dp_dpcd_read returns the number of bytes read. The previous code would print garbage on DPCD error, and would exit with on error on success. Signed-off-by: Simon Ser <contact@emersion.fr> Fixes: cb897542c6d2 ("drm/dp_mst: Fix W=1 warnings") Cc: Lyude Paul <lyude@redhat.com> Cc: Benjamin Gaignard <benjamin.gaignard@st.com> Reviewed-by: Jani Nikula <jani.nikula@intel.com> Link: https://patchwork.freedesktop.org/patch/473500/ Signed-off-by: Sasha Levin <sashal@kernel.org> Signed-off-by: Jialin Zhang <zhangjialin11@huawei.com> --- drivers/gpu/drm/drm_dp_mst_topology.c | 6 +++--- 1 file changed, 3 insertions(+), 3 deletions(-) diff --git a/drivers/gpu/drm/drm_dp_mst_topology.c b/drivers/gpu/drm/drm_dp_mst_topology.c index ab423b0413ee..4272cd3622f8 100644 --- a/drivers/gpu/drm/drm_dp_mst_topology.c +++ b/drivers/gpu/drm/drm_dp_mst_topology.c @@ -4856,14 +4856,14 @@ void drm_dp_mst_dump_topology(struct seq_file *m, seq_printf(m, "dpcd: %*ph\n", DP_RECEIVER_CAP_SIZE, buf); ret = drm_dp_dpcd_read(mgr->aux, DP_FAUX_CAP, buf, 2); - if (ret) { + if (ret != 2) { seq_printf(m, "faux/mst read failed\n"); goto out; } seq_printf(m, "faux/mst: %*ph\n", 2, buf); ret = drm_dp_dpcd_read(mgr->aux, DP_MSTM_CTRL, buf, 1); - if (ret) { + if (ret != 1) { seq_printf(m, "mst ctrl read failed\n"); goto out; } @@ -4871,7 +4871,7 @@ void drm_dp_mst_dump_topology(struct seq_file *m, /* dump the standard OUI branch header */ ret = drm_dp_dpcd_read(mgr->aux, DP_BRANCH_OUI, buf, DP_BRANCH_OUI_HEADER_SIZE); - if (ret) { + if (ret != DP_BRANCH_OUI_HEADER_SIZE) { seq_printf(m, "branch oui read failed\n"); goto out; } -- 2.25.1