[PATCH v1 1/1] drm/mediatek: Add return value check when reading DPCD

[Liankun Yang]

Returns the number of bytes transferred (1) on success.
Check the return value to confirm that AUX communication is successful.

Fixes: f70ac097a2cf ("drm/mediatek: Add MT8195 Embedded DisplayPort driver")

Signed-off-by: Liankun Yang <liankun.y...@mediatek.com>
---
 drivers/gpu/drm/mediatek/mtk_dp.c | 8 +++++++-
 1 file changed, 7 insertions(+), 1 deletion(-)

diff --git a/drivers/gpu/drm/mediatek/mtk_dp.c 
b/drivers/gpu/drm/mediatek/mtk_dp.c
index d8796a904eca..3cab65345d1e 100644
--- a/drivers/gpu/drm/mediatek/mtk_dp.c
+++ b/drivers/gpu/drm/mediatek/mtk_dp.c
@@ -2018,6 +2018,7 @@ static enum drm_connector_status mtk_dp_bdg_detect(struct 
drm_bridge *bridge)
        enum drm_connector_status ret = connector_status_disconnected;
        bool enabled = mtk_dp->enabled;
        u8 sink_count = 0;
+       size_t value;
 
        if (!mtk_dp->train_info.cable_plugged_in)
                return ret;
@@ -2032,7 +2033,12 @@ static enum drm_connector_status 
mtk_dp_bdg_detect(struct drm_bridge *bridge)
         * function, we just need to check the HPD connection to check
         * whether we connect to a sink device.
         */
-       drm_dp_dpcd_readb(&mtk_dp->aux, DP_SINK_COUNT, &sink_count);
+       value = drm_dp_dpcd_readb(&mtk_dp->aux, DP_SINK_COUNT, &sink_count);
+       if (value < 0) {
+               drm_err(mtk_dp->drm_dev, "Failed to read DP Sink Count: %zd\n", 
value);
+               return ret;
+       }
+
        if (DP_GET_SINK_COUNT(sink_count))
                ret = connector_status_connected;
 
-- 
2.45.2