From 3c9855f6dc1c68f7c4028f49bd8e3df7e4faae67 Mon Sep 17 00:00:00 2001 From: Ville Syrjälä Date: Tue, 8 Jul 2014 10:31:56 +0530 Subject: drm: Add drm_rotation_simplify() MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit drm_rotation_simplify() can be used to eliminate unsupported rotation flags. It will check if any unsupported flags are present, and if so it will modify the rotation to an alternate form by adding 180 degrees to rotation angle, and flipping the reflect x and y bits. The hope is that this identity transform will eliminate the unsupported flags. Of course that might not result in any more supported rotation, so the caller is still responsible for checking the result afterwards. Cc: dri-devel@lists.freedesktop.org Signed-off-by: Ville Syrjälä Reviewed-by: Imre Deak Acked-by: Dave Airlie Signed-off-by: Daniel Vetter --- drivers/gpu/drm/drm_crtc.c | 30 ++++++++++++++++++++++++++++++ 1 file changed, 30 insertions(+) (limited to 'drivers/gpu/drm/drm_crtc.c') diff --git a/drivers/gpu/drm/drm_crtc.c b/drivers/gpu/drm/drm_crtc.c index f224d4d1c0e..89bab66558e 100644 --- a/drivers/gpu/drm/drm_crtc.c +++ b/drivers/gpu/drm/drm_crtc.c @@ -4841,6 +4841,36 @@ int drm_format_vert_chroma_subsampling(uint32_t format) } EXPORT_SYMBOL(drm_format_vert_chroma_subsampling); +/** + * drm_rotation_simplify() - Try to simplify the rotation + * @rotation: Rotation to be simplified + * @supported_rotations: Supported rotations + * + * Attempt to simplify the rotation to a form that is supported. + * Eg. if the hardware supports everything except DRM_REFLECT_X + * one could call this function like this: + * + * drm_rotation_simplify(rotation, BIT(DRM_ROTATE_0) | + * BIT(DRM_ROTATE_90) | BIT(DRM_ROTATE_180) | + * BIT(DRM_ROTATE_270) | BIT(DRM_REFLECT_Y)); + * + * to eliminate the DRM_ROTATE_X flag. Depending on what kind of + * transforms the hardware supports, this function may not + * be able to produce a supported transform, so the caller should + * check the result afterwards. + */ +unsigned int drm_rotation_simplify(unsigned int rotation, + unsigned int supported_rotations) +{ + if (rotation & ~supported_rotations) { + rotation ^= BIT(DRM_REFLECT_X) | BIT(DRM_REFLECT_Y); + rotation = (rotation & ~0xf) | BIT((ffs(rotation & 0xf) + 1) % 4); + } + + return rotation; +} +EXPORT_SYMBOL(drm_rotation_simplify); + /** * drm_mode_config_init - initialize DRM mode_configuration structure * @dev: DRM device -- cgit v1.2.3-70-g09d2