[PATCH v7 01/11] drm/mediatek: dp: Add missing error checks in mtk_dp_parse_capabilities

[AngeloGioacchino Del Regno]

If reading the RX capabilities fails the training pattern will be set
wrongly: add error checking for drm_dp_read_dpcd_caps() and return if
anything went wrong with it.

While at it, also add a less critical error check when writing to
clear the ESI0 IRQ vector.

Fixes: f70ac097a2cf ("drm/mediatek: Add MT8195 Embedded DisplayPort driver")
Signed-off-by: AngeloGioacchino Del Regno 
<angelogioacchino.delre...@collabora.com>
Tested-by: Chen-Yu Tsai <we...@chromium.org>
Reviewed-by: Alexandre Mergnat <amerg...@baylibre.com>
---
 drivers/gpu/drm/mediatek/mtk_dp.c | 15 ++++++++++-----
 1 file changed, 10 insertions(+), 5 deletions(-)

diff --git a/drivers/gpu/drm/mediatek/mtk_dp.c 
b/drivers/gpu/drm/mediatek/mtk_dp.c
index 64eee77452c0..c58b775877a3 100644
--- a/drivers/gpu/drm/mediatek/mtk_dp.c
+++ b/drivers/gpu/drm/mediatek/mtk_dp.c
@@ -1588,7 +1588,9 @@ static int mtk_dp_parse_capabilities(struct mtk_dp 
*mtk_dp)
        u8 val;
        ssize_t ret;
 
-       drm_dp_read_dpcd_caps(&mtk_dp->aux, mtk_dp->rx_cap);
+       ret = drm_dp_read_dpcd_caps(&mtk_dp->aux, mtk_dp->rx_cap);
+       if (ret < 0)
+               return ret;
 
        if (drm_dp_tps4_supported(mtk_dp->rx_cap))
                mtk_dp->train_info.channel_eq_pattern = DP_TRAINING_PATTERN_4;
@@ -1615,10 +1617,13 @@ static int mtk_dp_parse_capabilities(struct mtk_dp 
*mtk_dp)
                        return ret == 0 ? -EIO : ret;
                }
 
-               if (val)
-                       drm_dp_dpcd_writeb(&mtk_dp->aux,
-                                          DP_DEVICE_SERVICE_IRQ_VECTOR_ESI0,
-                                          val);
+               if (val) {
+                       ret = drm_dp_dpcd_writeb(&mtk_dp->aux,
+                                                
DP_DEVICE_SERVICE_IRQ_VECTOR_ESI0,
+                                                val);
+                       if (ret < 0)
+                               return ret;
+               }
        }
 
        return 0;
-- 
2.41.0