[PATCH 5.19 303/717] drm/dp_mst: fix drm_dp_dpcd_read return value checks

Greg Kroah-Hartman
2022-10-22T08:19:52Z

From: Simon Ser <contact@emersion.fr>

[ 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>
---
drivers/gpu/drm/display/drm_dp_mst_topology.c | 6 +++---
1 file changed, 3 insertions(+), 3 deletions(-)

diff --git a/drivers/gpu/drm/display/drm_dp_mst_topology.c b/drivers/gpu/drm/display/drm_dp_mst_topology.c
index 18f2b6075b78..28dd741f7da1 100644
--- a/drivers/gpu/drm/display/drm_dp_mst_topology.c
+++ b/drivers/gpu/drm/display/drm_dp_mst_topology.c
@@ -4916,14 +4916,14 @@ 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;
}
@@ -4931,7 +4931,7 @@ 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;
}
--
2.35.1