Re: [PATCH v5 17/38] drm/vkms: Introduce configfs for plane rotation

[sashiko-bot@kernel.org]

Thank you for your contribution! Sashiko AI review found 1 potential issue(s) to consider:
- [Medium] `plane_default_rotation_store()` uses base 10 for string parsing, incorrectly rejecting documented hexadecimal values.
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commit 5edae796c7d28ebd799b4c01972a95ad90e32c05
Author: Louis Chauvet <louis.chauvet@bootlin.com>
Subject: drm/vkms: Introduce configfs for plane rotation

This commit introduces a new configfs interface to configure available and
default rotations per plane in VKMS. It adds supported_rotations and
default_rotation attributes, allowing userspace to select any combination of
rotations and reflections.

> diff --git a/drivers/gpu/drm/vkms/vkms_configfs.c b/drivers/gpu/drm/vkms/vkms_configfs.c
> index 0744ac40814d8..47b3a4aeee8dd 100644
> --- a/drivers/gpu/drm/vkms/vkms_configfs.c
> +++ b/drivers/gpu/drm/vkms/vkms_configfs.c

[ ... ]

> +static ssize_t plane_default_rotation_store(struct config_item *item,
> +					    const char *page, size_t count)
> +{
> +	struct vkms_configfs_plane *plane = plane_item_to_vkms_configfs_plane(item);
> +	int ret, val = 0;
> +
> +	ret = kstrtouint(page, 10, &val);

[Severity: Medium]
Does this code incorrectly reject the documented hexadecimal values?

The ABI documentation specifies the rotation values as hex bitmasks (e.g.,
0x01, 0x10). While plane_supported_rotations_store() correctly uses base 0
for kstrtouint(), using base 10 here forces it to reject hexadecimal strings.
This breaks userspace tools or scripts attempting to write the documented
hexadecimal values to default_rotation, forcing them to use base-10 instead.

> +	if (ret)
> +		return ret;
> +
> +	/* Should be a supported value */
> +	if (val & ~(DRM_MODE_ROTATE_MASK | DRM_MODE_REFLECT_MASK))
> +		return -EINVAL;
> +
> +	/* Should contain exactly one rotation */
> +	if (!is_power_of_2(val & DRM_MODE_ROTATE_MASK))
> +		return -EINVAL;

[ ... ]

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Sashiko AI review · https://sashiko.dev/#/patchset/20260627-vkms-all-config-v5-0-854aa0840926@bootlin.com?part=17