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, 84 insertions, 0 deletions

diff --git a/Documentation/usb/mtouchusb.rst b/Documentation/usb/mtouchusb.rst
new file mode 100644
index 000000000..5ae1f74fe
--- /dev/null
+++ b/Documentation/usb/mtouchusb.rst
@@ -0,0 +1,84 @@
+================
+mtouchusb driver
+================
+
+Changes
+=======
+
+- 0.3 - Created based off of scanner & INSTALL from the original touchscreen
+  driver on freecode (http://freecode.com/projects/3mtouchscreendriver)
+- Amended for linux-2.4.18, then 2.4.19
+
+- 0.5 - Complete rewrite using Linux Input in 2.6.3
+  Unfortunately no calibration support at this time
+
+- 1.4 - Multiple changes to support the EXII 5000UC and house cleaning
+  Changed reset from standard USB dev reset to vendor reset
+  Changed data sent to host from compensated to raw coordinates
+  Eliminated vendor/product module params
+  Performed multiple successful tests with an EXII-5010UC
+
+Supported Hardware
+==================
+
+::
+
+        All controllers have the Vendor: 0x0596 & Product: 0x0001
+
+
+        Controller Description          Part Number
+        ------------------------------------------------------
+
+        USB Capacitive - Pearl Case     14-205  (Discontinued)
+        USB Capacitive - Black Case     14-124  (Discontinued)
+        USB Capacitive - No Case        14-206  (Discontinued)
+
+        USB Capacitive - Pearl Case     EXII-5010UC
+        USB Capacitive - Black Case     EXII-5030UC
+        USB Capacitive - No Case        EXII-5050UC
+
+Driver Notes
+============
+
+Installation is simple, you only need to add Linux Input, Linux USB, and the
+driver to the kernel.  The driver can also be optionally built as a module.
+
+This driver appears to be one of possible 2 Linux USB Input Touchscreen
+drivers.  Although 3M produces a binary only driver available for
+download, I persist in updating this driver since I would like to use the
+touchscreen for embedded apps using QTEmbedded, DirectFB, etc. So I feel the
+logical choice is to use Linux Input.
+
+Currently there is no way to calibrate the device via this driver.  Even if
+the device could be calibrated, the driver pulls to raw coordinate data from
+the controller.  This means calibration must be performed within the
+userspace.
+
+The controller screen resolution is now 0 to 16384 for both X and Y reporting
+the raw touch data.  This is the same for the old and new capacitive USB
+controllers.
+
+Perhaps at some point an abstract function will be placed into evdev so
+generic functions like calibrations, resets, and vendor information can be
+requested from the userspace (And the drivers would handle the vendor specific
+tasks).
+
+TODO
+====
+
+Implement a control urb again to handle requests to and from the device
+such as calibration, etc once/if it becomes available.
+
+Disclaimer
+==========
+
+I am not a MicroTouch/3M employee, nor have I ever been.  3M does not support
+this driver!  If you want touch drivers only supported within X, please go to:
+
+http://www.3m.com/3MTouchSystems/
+
+Thanks
+======
+
+A huge thank you to 3M Touch Systems for the EXII-5010UC controllers for
+testing!