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, 52 insertions, 0 deletions

diff --git a/Documentation/power/drivers-testing.rst b/Documentation/power/drivers-testing.rst
new file mode 100644
index 000000000..d77d2894f
--- /dev/null
+++ b/Documentation/power/drivers-testing.rst
@@ -0,0 +1,52 @@
+====================================================
+Testing suspend and resume support in device drivers
+====================================================
+
+	(C) 2007 Rafael J. Wysocki <rjw@sisk.pl>, GPL
+
+1. Preparing the test system
+============================
+
+Unfortunately, to effectively test the support for the system-wide suspend and
+resume transitions in a driver, it is necessary to suspend and resume a fully
+functional system with this driver loaded.  Moreover, that should be done
+several times, preferably several times in a row, and separately for hibernation
+(aka suspend to disk or STD) and suspend to RAM (STR), because each of these
+cases involves slightly different operations and different interactions with
+the machine's BIOS.
+
+Of course, for this purpose the test system has to be known to suspend and
+resume without the driver being tested.  Thus, if possible, you should first
+resolve all suspend/resume-related problems in the test system before you start
+testing the new driver.  Please see Documentation/power/basic-pm-debugging.rst
+for more information about the debugging of suspend/resume functionality.
+
+2. Testing the driver
+=====================
+
+Once you have resolved the suspend/resume-related problems with your test system
+without the new driver, you are ready to test it:
+
+a) Build the driver as a module, load it and try the test modes of hibernation
+   (see: Documentation/power/basic-pm-debugging.rst, 1).
+
+b) Load the driver and attempt to hibernate in the "reboot", "shutdown" and
+   "platform" modes (see: Documentation/power/basic-pm-debugging.rst, 1).
+
+c) Compile the driver directly into the kernel and try the test modes of
+   hibernation.
+
+d) Attempt to hibernate with the driver compiled directly into the kernel
+   in the "reboot", "shutdown" and "platform" modes.
+
+e) Try the test modes of suspend (see:
+   Documentation/power/basic-pm-debugging.rst, 2).  [As far as the STR tests are
+   concerned, it should not matter whether or not the driver is built as a
+   module.]
+
+f) Attempt to suspend to RAM using the s2ram tool with the driver loaded
+   (see: Documentation/power/basic-pm-debugging.rst, 2).
+
+Each of the above tests should be repeated several times and the STD tests
+should be mixed with the STR tests.  If any of them fails, the driver cannot be
+regarded as suspend/resume-safe.