Re: [PATCH 2/3] HID: valve-index: Reboot headset on system power transitions

[Greg Kroah-Hartman <gregkh@linuxfoundation.org>]

On Thu, Sep 10, 2026 at 12:02:53PM -0500, Mario Limonciello wrote:
> The Valve Index HMD stops serving its EDID after the host disables the
> DisplayPort PHY.  The headset remains powered by its breakout box across
> suspend and shutdown, so the bad state survives and the next connector
> detection reports "No EDID read".  The HMD then appears as a synthesized
> 640x480 display until it is power-cycled.
> 
> The 64-byte HID output report 0x16 with command 0x01 reboots the headset
> and restores its EDID service.  Add a device-specific driver which sends
> this report for system sleep transitions and orderly shutdown while leaving
> runtime autosuspend alone.
> 
> Resume a runtime-suspended interface for a shutdown request and restrict
> the command to the composite interface which declares report 0x16.
> 
> Closes: https://gitlab.freedesktop.org/drm/amd/-/work_items/4333
> Link: https://github.com/ValveSoftware/SteamVR-for-Linux/issues/939
> Assisted-by: LLM
> Co-developed-by: Curtis Vogt <curtis.vogt@gmail.com>
> Signed-off-by: Curtis Vogt <curtis.vogt@gmail.com>
> Signed-off-by: Mario Limonciello <mario.limonciello@amd.com>
> ---
>  .../ABI/testing/sysfs-driver-hid-valve-index  |  12 ++
>  drivers/hid/Kconfig                           |  11 ++
>  drivers/hid/Makefile                          |   1 +
>  drivers/hid/hid-ids.h                         |   1 +
>  drivers/hid/hid-valve-index.c                 | 142 ++++++++++++++++++
>  5 files changed, 167 insertions(+)
>  create mode 100644 Documentation/ABI/testing/sysfs-driver-hid-valve-index
>  create mode 100644 drivers/hid/hid-valve-index.c
> 
> diff --git a/Documentation/ABI/testing/sysfs-driver-hid-valve-index b/Documentation/ABI/testing/sysfs-driver-hid-valve-index
> new file mode 100644
> index 0000000000000..47d8c26b1eace
> --- /dev/null
> +++ b/Documentation/ABI/testing/sysfs-driver-hid-valve-index
> @@ -0,0 +1,12 @@
> +What:		/sys/bus/hid/devices/<bus>:<vid>:<pid>.<n>/reboot
> +Date:		October 2026
> +Contact:	linux-input@vger.kernel.org
> +Description:
> +		Writing a boolean true value reboots the Valve Index headset to
> +		recover its EDID service. Writing a boolean false value has no
> +		effect. This file is write-only.

Shouldn't this just be a debugfs file?  Making it a sysfs file seems
"risky" as it's not a normal operation.

> +		The Valve Index is a composite HID device. The reboot command is
> +		only supported by the interface that provides the headset's 64-byte
> +		output report. Writing true to this file on another interface fails
> +		with -ENODEV.

Why would it be present on "another interface'?  That feels wrong.

thanks,

greg k-h