drm/mediatek: Add missing IS_ERR check for ovl_adaptor platform devicegrafted

platform_device_register_data() can fail and return an ERR_PTR, but the
return value is used without checking, leading to an invalid pointer
being stored in ddp_comp[].dev and passed to component_match_add() and
mtk_ddp_comp_init(), which could result in a kernel crash.

Add an IS_ERR() check to jump to the error handling path on failure.

Fixes: 0d9eee9118b7 ("drm/mediatek: Add drm ovl_adaptor sub driver for MT8195")
Cc: stable@vger.kernel.org
Signed-off-by: Haojie Li <lihaojie@kylinos.cn>
Reviewed-by: CK Hu <ck.hu@mediatek.com>
Link: https://patchwork.kernel.org/project/linux-mediatek/patch/20260825100845.438893-1-lihaojie@kylinos.cn/
Signed-off-by: Chun-Kuang Hu <chunkuang.hu@kernel.org>

1 files changed, 56 insertions, 0 deletions

diff --git a/Documentation/block/cmdline-partition.rst b/Documentation/block/cmdline-partition.rst
new file mode 100644
index 000000000..526ba201d
--- /dev/null
+++ b/Documentation/block/cmdline-partition.rst
@@ -0,0 +1,56 @@
+==============================================
+Embedded device command line partition parsing
+==============================================
+
+The "blkdevparts" command line option adds support for reading the
+block device partition table from the kernel command line.
+
+It is typically used for fixed block (eMMC) embedded devices.
+It has no MBR, so saves storage space. Bootloader can be easily accessed
+by absolute address of data on the block device.
+Users can easily change the partition.
+
+The format for the command line is just like mtdparts:
+
+blkdevparts=<blkdev-def>[;<blkdev-def>]
+  <blkdev-def> := <blkdev-id>:<partdef>[,<partdef>]
+    <partdef> := <size>[@<offset>](part-name)
+
+<blkdev-id>
+    block device disk name. Embedded device uses fixed block device.
+    Its disk name is also fixed, such as: mmcblk0, mmcblk1, mmcblk0boot0.
+
+<size>
+    partition size, in bytes, such as: 512, 1m, 1G.
+    size may contain an optional suffix of (upper or lower case):
+
+      K, M, G, T, P, E.
+
+    "-" is used to denote all remaining space.
+
+<offset>
+    partition start address, in bytes.
+    offset may contain an optional suffix of (upper or lower case):
+
+      K, M, G, T, P, E.
+
+(part-name)
+    partition name. Kernel sends uevent with "PARTNAME". Application can
+    create a link to block device partition with the name "PARTNAME".
+    User space application can access partition by partition name.
+
+ro
+    read-only. Flag the partition as read-only.
+
+Example:
+
+    eMMC disk names are "mmcblk0" and "mmcblk0boot0".
+
+  bootargs::
+
+    'blkdevparts=mmcblk0:1G(data0),1G(data1),-;mmcblk0boot0:1m(boot)ro,-(kernel)'
+
+  dmesg::
+
+    mmcblk0: p1(data0) p2(data1) p3()
+    mmcblk0boot0: p1(boot) p2(kernel)