FAILED: patch "[PATCH] drm/mediatek: fix OF sibling-node lookup" failed to apply to 4.9-stable tree

From ceff2f4dcd44abf35864d9a99f85ac619e89a01d Mon Sep 17 00:00:00 2001

The patch below does not apply to the 4.9-stable tree.
If someone wants it applied there, or to any other stable or longterm tree, then please email the backport, including the original git commit id to <[email protected]>.

------------------ original commit in Linus's tree ------------------

From ceff2f4dcd44abf35864d9a99f85ac619e89a01d Mon Sep 17 00:00:00 2001
From: Johan Hovold <[email protected]>
Date: Mon, 27 Aug 2018 10:21:46 +0200
Subject: [PATCH] drm/mediatek: fix OF sibling-node lookup

Use the new of_get_compatible_child() helper to lookup the sibling instead of using of_find_compatible_node(), which searches the entire tree from a given start node and thus can return an unrelated (i.e. non-sibling) node.

This also addresses a potential use-after-free (e.g. after probe deferral) as the tree-wide helper drops a reference to its first argument (i.e. the parent device node).

While at it, also fix the related cec-node reference leak.

Fixes 8f83f26891e1 ("drm/mediatek: Add HDMI support")

Cc stable <[email protected]> # 4.8

Cc Junzhi Zhao <[email protected]>

Cc Philipp Zabel <[email protected]>

Cc CK Hu <[email protected]>

Cc David Airlie <[email protected]>

Signed-off-by Johan Hovold <[email protected]>

Signed-off-by Rob Herring <[email protected]>

drivers/gpu/drm/mediatek/mtk_hdmi.c +3 -2

index 2d45d1dd9554..643f5edd68fe 100644
@@ -1446,8 +1446,7 @@ static int mtk_hdmi_dt_parse_pdata(struct mtk_hdmi *hdmi,
 	}
 
 	/* The CEC module handles HDMI hotplug detection */
-	cec_np = of_find_compatible_node(np->parent, NULL,
-					 "mediatek,mt8173-cec");
+	cec_np = of_get_compatible_child(np->parent, "mediatek,mt8173-cec");
 	if (!cec_np) {
 		dev_err(dev, "Failed to find CEC node\n");
 		return -EINVAL;

@@ -1457,8 +1456,10 @@ static int mtk_hdmi_dt_parse_pdata(struct mtk_hdmi *hdmi,
 	if (!cec_pdev) {
 		dev_err(hdmi->dev, "Waiting for CEC device %pOF\n",
 			cec_np);
+		of_node_put(cec_np);
 		return -EPROBE_DEFER;
 	}
+	of_node_put(cec_np);
 	hdmi->cec_dev = &cec_pdev->dev;
 
 	/*

Quoted 5 lines · Greg Kroah-Hartman

The patch below does not apply to the 4.9-stable tree.
If someone wants it applied there, or to any other stable or longterm tree, then please email the backport, including the original git commit id to <[email protected]>.

This one also depends on

36156f9241cb ("of: add helper to lookup compatible child node")

Quoted 7 lines · Johan Hovold

Quoted 5 lines · Greg Kroah-Hartman

The patch below does not apply to the 4.9-stable tree.
If someone wants it applied there, or to any other stable or longterm tree, then please email the backport, including the original git commit id to <[email protected]>.

Quoted 3 lines

This one also depends on

36156f9241cb ("of: add helper to lookup compatible child node")

It seems to have more dependencies for 4.9.

From 25904658b8a0975376a9118cfc07f5f3ebb1ea34 Mon Sep 17 00:00:00 2001

Quoted 10 lines · Sasha Levin

Quoted 9 lines · Johan Hovold

Quoted 5 lines · Greg Kroah-Hartman

The patch below does not apply to the 4.9-stable tree.
If someone wants it applied there, or to any other stable or longterm tree, then please email the backport, including the original git commit id to <[email protected]>.

This one also depends on

Quoted 3 lines

Quoted 1 line

36156f9241cb ("of: add helper to lookup compatible child node")

It seems to have more dependencies for 4.9.

Apparently just a trivial context change due to 4bf99144d2b4 ("drm:
Convert to using %pOF instead of full_name").

Compile-tested backport below.