Patch "drm/mediatek: dp: Add missing error checks in mtk_dp_parse_capabilities" has been added to the 6.4-stable tree

[Sasha Levin <sashal@xxxxxxxxxx>]

This is a note to let you know that I've just added the patch titled

    drm/mediatek: dp: Add missing error checks in mtk_dp_parse_capabilities

to the 6.4-stable tree which can be found at:
    http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary

The filename of the patch is:
     drm-mediatek-dp-add-missing-error-checks-in-mtk_dp_p.patch
and it can be found in the queue-6.4 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.



commit 8219bd74625a1710577e0268dc9d0159e5a1bb2b
Author: AngeloGioacchino Del Regno <angelogioacchino.delregno@xxxxxxxxxxxxx>
Date:   Tue Jul 25 09:32:24 2023 +0200

    drm/mediatek: dp: Add missing error checks in mtk_dp_parse_capabilities
    
    [ Upstream commit cfc146137a9f12e883ba64bc496b6da4d23f26d5 ]
    
    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@xxxxxxxxxxxxx>
    Tested-by: Chen-Yu Tsai <wenst@xxxxxxxxxxxx>
    Reviewed-by: Alexandre Mergnat <amergnat@xxxxxxxxxxxx>
    Reviewed-by: CK Hu <ck.hu@xxxxxxxxxxxx>
    Link: https://patchwork.kernel.org/project/dri-devel/patch/20230725073234.55892-2-angelogioacchino.delregno@xxxxxxxxxxxxx/
    Signed-off-by: Chun-Kuang Hu <chunkuang.hu@xxxxxxxxxx>
    Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>

diff --git a/drivers/gpu/drm/mediatek/mtk_dp.c b/drivers/gpu/drm/mediatek/mtk_dp.c
index 64eee77452c04..c58b775877a31 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;