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, 77 insertions, 0 deletions

diff --git a/Documentation/admin-guide/media/ci.rst b/Documentation/admin-guide/media/ci.rst
new file mode 100644
index 000000000..ded4d8fbb
--- /dev/null
+++ b/Documentation/admin-guide/media/ci.rst
@@ -0,0 +1,77 @@
+.. SPDX-License-Identifier: GPL-2.0
+
+Digital TV Conditional Access Interface
+=======================================
+
+
+.. note::
+
+   This documentation is outdated.
+
+This document describes the usage of the high level CI API as
+in accordance to the Linux DVB API. This is a not a documentation for the,
+existing low level CI API.
+
+.. note::
+
+   For the Twinhan/Twinhan clones, the dst_ca module handles the CI
+   hardware handling. This module is loaded automatically if a CI
+   (Common Interface, that holds the CAM (Conditional Access Module)
+   is detected.
+
+ca_zap
+~~~~~~
+
+A userspace application, like ``ca_zap`` is required to handle encrypted
+MPEG-TS streams.
+
+The ``ca_zap`` userland application is in charge of sending the
+descrambling related information to the Conditional Access Module (CAM).
+
+This application requires the following to function properly as of now.
+
+a) Tune to a valid channel, with szap.
+
+  eg: $ szap -c channels.conf -r "TMC" -x
+
+b) a channels.conf containing a valid PMT PID
+
+  eg: TMC:11996:h:0:27500:278:512:650:321
+
+  here 278 is a valid PMT PID. the rest of the values are the
+  same ones that szap uses.
+
+c) after running a szap, you have to run ca_zap, for the
+   descrambler to function,
+
+  eg: $ ca_zap channels.conf "TMC"
+
+d) Hopefully enjoy your favourite subscribed channel as you do with
+   a FTA card.
+
+.. note::
+
+  Currently ca_zap, and dst_test, both are meant for demonstration
+  purposes only, they can become full fledged applications if necessary.
+
+
+Cards that fall in this category
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+
+At present the cards that fall in this category are the Twinhan and its
+clones, these cards are available as VVMER, Tomato, Hercules, Orange and
+so on.
+
+CI modules that are supported
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+
+The CI module support is largely dependent upon the firmware on the cards
+Some cards do support almost all of the available CI modules. There is
+nothing much that can be done in order to make additional CI modules
+working with these cards.
+
+Modules that have been tested by this driver at present are
+
+(1) Irdeto 1 and 2 from SCM
+(2) Viaccess from SCM
+(3) Dragoncam