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From:   AngeloGioacchino Del Regno 
        <angelogioacchino.delregno@collabora.com>
To:     chunkuang.hu@kernel.org
Cc:     p.zabel@pengutronix.de, airlied@gmail.com, daniel@ffwll.ch,
        matthias.bgg@gmail.com, angelogioacchino.delregno@collabora.com,
        dri-devel@lists.freedesktop.org,
        linux-mediatek@lists.infradead.org, linux-kernel@vger.kernel.org,
        linux-arm-kernel@lists.infradead.org, kernel@collabora.com,
        wenst@chromium.org, nfraprado@collabora.com
Subject: [PATCH v6 01/11] drm/mediatek: dp: Add missing error checks in mtk_dp_parse_capabilities
Date:   Mon, 17 Jul 2023 16:14:28 +0200
Message-Id: <20230717141438.274419-2-angelogioacchino.delregno@collabora.com>
In-Reply-To: <20230717141438.274419-1-angelogioacchino.delregno@collabora.com>
References: <20230717141438.274419-1-angelogioacchino.delregno@collabora.com>
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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.delregno@collabora.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;
-- 
2.40.1