From bce7698e2e6565bb765bd0522337f29f5f312624 Mon Sep 17 00:00:00 2001 From: Haojie Li Date: Tue, 25 Aug 2026 18:08:45 +0800 Subject: drm/mediatek: Add missing IS_ERR check for ovl_adaptor platform device 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 Reviewed-by: CK Hu Link: https://patchwork.kernel.org/project/linux-mediatek/patch/20260825100845.438893-1-lihaojie@kylinos.cn/ Signed-off-by: Chun-Kuang Hu --- Documentation/input/userio.rst | 104 +++++++++++++++++++++++++++++++++++++++++ 1 file changed, 104 insertions(+) create mode 100644 Documentation/input/userio.rst (limited to 'Documentation/input/userio.rst') diff --git a/Documentation/input/userio.rst b/Documentation/input/userio.rst new file mode 100644 index 000000000..7aaaa629b --- /dev/null +++ b/Documentation/input/userio.rst @@ -0,0 +1,104 @@ +.. include:: + +=================== +The userio Protocol +=================== + + +:Copyright: |copy| 2015 Lyude Paul + +Sponsored by Red Hat + + +Introduction +============= + +This module is intended to try to make the lives of input driver developers +easier by allowing them to test various serio devices (mainly the various +touchpads found on laptops) without having to have the physical device in front +of them. userio accomplishes this by allowing any privileged userspace program +to directly interact with the kernel's serio driver and control a virtual serio +port from there. + +Usage overview +============== + +In order to interact with the userio kernel module, one simply opens the +/dev/userio character device in their applications. Commands are sent to the +kernel module by writing to the device, and any data received from the serio +driver is read as-is from the /dev/userio device. All of the structures and +macros you need to interact with the device are defined in and +. + +Command Structure +================= + +The struct used for sending commands to /dev/userio is as follows:: + + struct userio_cmd { + __u8 type; + __u8 data; + }; + +``type`` describes the type of command that is being sent. This can be any one +of the USERIO_CMD macros defined in . ``data`` is the argument +that goes along with the command. In the event that the command doesn't have an +argument, this field can be left untouched and will be ignored by the kernel. +Each command should be sent by writing the struct directly to the character +device. In the event that the command you send is invalid, an error will be +returned by the character device and a more descriptive error will be printed +to the kernel log. Only one command can be sent at a time, any additional data +written to the character device after the initial command will be ignored. + +To close the virtual serio port, just close /dev/userio. + +Commands +======== + +USERIO_CMD_REGISTER +~~~~~~~~~~~~~~~~~~~ + +Registers the port with the serio driver and begins transmitting data back and +forth. Registration can only be performed once a port type is set with +USERIO_CMD_SET_PORT_TYPE. Has no argument. + +USERIO_CMD_SET_PORT_TYPE +~~~~~~~~~~~~~~~~~~~~~~~~ + +Sets the type of port we're emulating, where ``data`` is the port type being +set. Can be any of the serio type macros from . For example: +SERIO_8042 would set the port type to be a normal PS/2 port. + +USERIO_CMD_SET_PORT_PROTO +~~~~~~~~~~~~~~~~~~~~~~~~~ + +Sets the protocol of port we're emulating, where ``data`` is the protocol being +set. Can be any of the serio proto macros from . For example: +SERIO_IFORCE would set the port type to be an I-Force serial joystick. + +USERIO_CMD_SET_PORT_ID +~~~~~~~~~~~~~~~~~~~~~~ + +Sets the ``id`` value on the identification of port we're emulating, where +``data`` is the value being set. + +USERIO_CMD_SET_PORT_EXTRA +~~~~~~~~~~~~~~~~~~~~~~~~~ + +Sets the ``extra`` value on the identification of port we're emulating, where +``data`` is the value being set. + +USERIO_CMD_SEND_INTERRUPT +~~~~~~~~~~~~~~~~~~~~~~~~~ + +Sends an interrupt through the virtual serio port to the serio driver, where +``data`` is the interrupt data being sent. + +Userspace tools +=============== + +The userio userspace tools are able to record PS/2 devices using some of the +debugging information from i8042, and play back the devices on /dev/userio. The +latest version of these tools can be found at: + + https://github.com/Lyude/ps2emu -- cgit v1.3.1