Re: [PATCH 3/3] Input: misc: Add AMD SFH tablet-mode switch driver

[sashiko-bot@kernel.org]

Thank you for your contribution! Sashiko AI review found 2 potential issue(s) to consider:
- [Medium] The initial hardware state of the tablet mode switch is redundantly queried and synchronized after `input_register_device()` exposes the device to userspace, creating a race condition.
- [Low] Violation of input subsystem naming convention for error variables.
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--- Patch [3]: [PATCH 3/3] Input: misc: Add AMD SFH tablet-mode switch driver ---
commit e88c97b2482f6ed434b346336b9c6f9164d73473
Author: Basavaraj Natikar <Basavaraj.Natikar@amd.com>

Input: misc: Add AMD SFH tablet-mode switch driver

This commit introduces a new driver for AMD convertible laptops. It exposes
the SW_TABLET_MODE switch by polling the operating-mode sensor provided by
the AMD Sensor Fusion Hub.

> diff --git a/drivers/input/misc/amd_sfh_tabletmode.c b/drivers/input/misc/amd_sfh_tabletmode.c
> new file mode 100644
> index 0000000000000..f88edebbf35d5
> --- /dev/null
> +++ b/drivers/input/misc/amd_sfh_tabletmode.c

[ ... ]

> +static int sfh_tm_probe(struct auxiliary_device *auxdev,
> +			const struct auxiliary_device_id *id)
> +{
> +	struct amd_sfh_info info = {};
> +	struct device *dev = &auxdev->dev;
> +	struct input_dev *input;
> +	int rc;

[Severity: Low]
This isn't a bug, but does using 'rc' instead of 'error' or 'err' violate
the input subsystem maintainer preference? 

The input subsystem guidelines suggest using 'error' or 'err' for variables
that only hold negative error codes and 0 for success.

[ ... ]

> +	rc = input_setup_polling(input, sfh_tm_poll);
> +	if (rc)
> +		return rc;
> +	input_set_poll_interval(input, POLL_INTERVAL_MS);
> +
> +	rc = input_register_device(input);
> +	if (rc)
> +		return rc;
> +
> +	sfh_tm_poll(input);

[Severity: Medium]
Should sfh_tm_poll() be called before input_register_device()?

Calling it after registration exposes a race condition where userspace
components reacting to the device creation uevent might read the
SW_TABLET_MODE state before sfh_tm_poll() executes.

They will read the default uninitialized state (0), which may incorrectly
leave the keyboard and touchpad active if the device is actually folded into
tablet mode.

> +
> +	return 0;
> +}

-- 
Sashiko AI review · https://sashiko.dev/#/patchset/20260721174422.3109166-1-Basavaraj.Natikar@amd.com?part=3