linux-kernel - Re: [PATCH RESEND v2 07/32] drm/blend: Get a rotation name from it's bitfield

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Message-ID: <aRXp0rfAoXxJ8PEh@fedora>
Date: Thu, 13 Nov 2025 15:23:14 +0100
From: José Expósito <jose.exposito89@...il.com>
To: Louis Chauvet <louis.chauvet@...tlin.com>
Cc: Haneen Mohammed <hamohammed.sa@...il.com>,
	Simona Vetter <simona@...ll.ch>,
	Melissa Wen <melissa.srw@...il.com>,
	Maarten Lankhorst <maarten.lankhorst@...ux.intel.com>,
	Maxime Ripard <mripard@...nel.org>,
	Thomas Zimmermann <tzimmermann@...e.de>,
	David Airlie <airlied@...il.com>, Jonathan Corbet <corbet@....net>,
	victoria@...tem76.com, sebastian.wick@...hat.com,
	thomas.petazzoni@...tlin.com, dri-devel@...ts.freedesktop.org,
	linux-kernel@...r.kernel.org, linux-doc@...r.kernel.org
Subject: Re: [PATCH RESEND v2 07/32] drm/blend: Get a rotation name from it's
 bitfield

On Wed, Oct 29, 2025 at 03:36:44PM +0100, Louis Chauvet wrote:
> Having the rotation/reflection name from its value can be useful for
> debugging purpose. Extract the rotation property table and implement
> drm_get_rotation_name.

Reviewed-by: José Expósito <jose.exposito@...hat.com>
 
> Signed-off-by: Louis Chauvet <louis.chauvet@...tlin.com>
> ---
>  drivers/gpu/drm/drm_blend.c | 35 ++++++++++++++++++++++++++---------
>  include/drm/drm_blend.h     |  2 ++
>  2 files changed, 28 insertions(+), 9 deletions(-)
> 
> diff --git a/drivers/gpu/drm/drm_blend.c b/drivers/gpu/drm/drm_blend.c
> index 6852d73c931c..bc7c05e20242 100644
> --- a/drivers/gpu/drm/drm_blend.c
> +++ b/drivers/gpu/drm/drm_blend.c
> @@ -241,6 +241,31 @@ int drm_plane_create_alpha_property(struct drm_plane *plane)
>  }
>  EXPORT_SYMBOL(drm_plane_create_alpha_property);
>  
> +static const struct drm_prop_enum_list rotation_props[] = {
> +	{ __builtin_ffs(DRM_MODE_ROTATE_0) - 1,   "rotate-0" },
> +	{ __builtin_ffs(DRM_MODE_ROTATE_90) - 1,  "rotate-90" },
> +	{ __builtin_ffs(DRM_MODE_ROTATE_180) - 1, "rotate-180" },
> +	{ __builtin_ffs(DRM_MODE_ROTATE_270) - 1, "rotate-270" },
> +	{ __builtin_ffs(DRM_MODE_REFLECT_X) - 1,  "reflect-x" },
> +	{ __builtin_ffs(DRM_MODE_REFLECT_Y) - 1,  "reflect-y" },
> +};
> +
> +/**
> + * drm_get_rotation_name - Return the name of a rotation
> + * @rotation: The rotation mask (DRM_MODE_ROTATE_* | DRM_MODE_REFLECT_*)
> + *
> + * Returns: the name of the rotation type (unknown) if rotation is not
> + * a known rotation/reflection
> + */
> +const char *drm_get_rotation_name(unsigned int rotation)
> +{
> +	if (rotation < ARRAY_SIZE(rotation_props))
> +		return rotation_props[rotation].name;
> +
> +	return "(unknown)";
> +}
> +EXPORT_SYMBOL(drm_get_rotation_name);
> +
>  /**
>   * drm_plane_create_rotation_property - create a new rotation property
>   * @plane: drm plane
> @@ -279,14 +304,6 @@ int drm_plane_create_rotation_property(struct drm_plane *plane,
>  				       unsigned int rotation,
>  				       unsigned int supported_rotations)
>  {
> -	static const struct drm_prop_enum_list props[] = {
> -		{ __builtin_ffs(DRM_MODE_ROTATE_0) - 1,   "rotate-0" },
> -		{ __builtin_ffs(DRM_MODE_ROTATE_90) - 1,  "rotate-90" },
> -		{ __builtin_ffs(DRM_MODE_ROTATE_180) - 1, "rotate-180" },
> -		{ __builtin_ffs(DRM_MODE_ROTATE_270) - 1, "rotate-270" },
> -		{ __builtin_ffs(DRM_MODE_REFLECT_X) - 1,  "reflect-x" },
> -		{ __builtin_ffs(DRM_MODE_REFLECT_Y) - 1,  "reflect-y" },
> -	};
>  	struct drm_property *prop;
>  
>  	WARN_ON((supported_rotations & DRM_MODE_ROTATE_MASK) == 0);
> @@ -294,7 +311,7 @@ int drm_plane_create_rotation_property(struct drm_plane *plane,
>  	WARN_ON(rotation & ~supported_rotations);
>  
>  	prop = drm_property_create_bitmask(plane->dev, 0, "rotation",
> -					   props, ARRAY_SIZE(props),
> +					   rotation_props, ARRAY_SIZE(rotation_props),
>  					   supported_rotations);
>  	if (!prop)
>  		return -ENOMEM;
> diff --git a/include/drm/drm_blend.h b/include/drm/drm_blend.h
> index 88bdfec3bd88..381d1f8d815b 100644
> --- a/include/drm/drm_blend.h
> +++ b/include/drm/drm_blend.h
> @@ -42,6 +42,8 @@ static inline bool drm_rotation_90_or_270(unsigned int rotation)
>  
>  #define DRM_BLEND_ALPHA_OPAQUE		0xffff
>  
> +const char *drm_get_rotation_name(unsigned int rotation);
> +
>  int drm_plane_create_alpha_property(struct drm_plane *plane);
>  int drm_plane_create_rotation_property(struct drm_plane *plane,
>  				       unsigned int rotation,
> 
> -- 
> 2.51.0
>