drm/vkms: add rotate-0 and reflect-x property

Currently, vkms doesn't support any reflection property. Therefore, add
the reflect-x property to vkms through a software implementation of the
operation. This is possible by reverse reading the x axis during the
blending.

Tested with igt@kms_rotation_crc@primary-reflect-x [1] and
igt@kms_rotation_crc@sprite-reflect-x [1].

[1] https://patchwork.freedesktop.org/series/116025/Signed-off-by: Maíra Canal <mcanal@igalia.com>
Reviewed-by: Melissa Wen <mwen@igalia.com>
Signed-off-by: Maíra Canal <mairacanal@riseup.net>
Link: https://patchwork.freedesktop.org/patch/msgid/20230418130525.128733-3-mcanal@igalia.com

drivers/gpu/drm/vkms/vkms_composer.c

@@ -55,7 +55,7 @@ static void pre_mul_alpha_blend(struct vkms_frame_info *frame_info,
 
 static bool check_y_limit(struct vkms_frame_info *frame_info, int y)
 {
-	if (y >= frame_info->dst.y1 && y < frame_info->dst.y2)
+	if (y >= frame_info->rotated.y1 && y < frame_info->rotated.y2)
 		return true;
 
 	return false;

drivers/gpu/drm/vkms/vkms_drv.h

@@ -26,7 +26,9 @@
 struct vkms_frame_info {
 	struct drm_framebuffer *fb;
 	struct drm_rect src, dst;
+	struct drm_rect rotated;
 	struct iosys_map map[DRM_FORMAT_MAX_PLANES];
+	unsigned int rotation;
 	unsigned int offset;
 	unsigned int pitch;
 	unsigned int cpp;

drivers/gpu/drm/vkms/vkms_formats.c

@@ -37,11 +37,18 @@ static void *packed_pixels_addr(const struct vkms_frame_info *frame_info,
 static void *get_packed_src_addr(const struct vkms_frame_info *frame_info, int y)
 {
 	int x_src = frame_info->src.x1 >> 16;
-	int y_src = y - frame_info->dst.y1 + (frame_info->src.y1 >> 16);
+	int y_src = y - frame_info->rotated.y1 + (frame_info->src.y1 >> 16);
 
 	return packed_pixels_addr(frame_info, x_src, y_src);
 }
 
+static int get_x_position(const struct vkms_frame_info *frame_info, int limit, int x)
+{
+	if (frame_info->rotation & DRM_MODE_REFLECT_X)
+		return limit - x - 1;
+	return x;
+}
+
 static void ARGB8888_to_argb_u16(u8 *src_pixels, struct pixel_argb_u16 *out_pixel)
 {
 	/*
@@ -109,8 +116,11 @@ void vkms_compose_row(struct line_buffer *stage_buffer, struct vkms_plane_state
 	u8 *src_pixels = get_packed_src_addr(frame_info, y);
 	int limit = min_t(size_t, drm_rect_width(&frame_info->dst), stage_buffer->n_pixels);
 
-	for (size_t x = 0; x < limit; x++, src_pixels += frame_info->cpp)
-		plane->pixel_read(src_pixels, &out_pixels[x]);
+	for (size_t x = 0; x < limit; x++, src_pixels += frame_info->cpp) {
+		int x_pos = get_x_position(frame_info, limit, x);
+
+		plane->pixel_read(src_pixels, &out_pixels[x_pos]);
+	}
 }
 
 /*

drivers/gpu/drm/vkms/vkms_plane.c

@@ -4,6 +4,7 @@
 
 #include <drm/drm_atomic.h>
 #include <drm/drm_atomic_helper.h>
+#include <drm/drm_blend.h>
 #include <drm/drm_fourcc.h>
 #include <drm/drm_gem_atomic_helper.h>
 #include <drm/drm_gem_framebuffer_helper.h>
@@ -111,9 +112,16 @@ static void vkms_plane_atomic_update(struct drm_plane *plane,
 	frame_info = vkms_plane_state->frame_info;
 	memcpy(&frame_info->src, &new_state->src, sizeof(struct drm_rect));
 	memcpy(&frame_info->dst, &new_state->dst, sizeof(struct drm_rect));
+	memcpy(&frame_info->rotated, &new_state->dst, sizeof(struct drm_rect));
 	frame_info->fb = fb;
 	memcpy(&frame_info->map, &shadow_plane_state->data, sizeof(frame_info->map));
 	drm_framebuffer_get(frame_info->fb);
+	frame_info->rotation = drm_rotation_simplify(new_state->rotation, DRM_MODE_ROTATE_0 |
+						     DRM_MODE_REFLECT_X);
+
+	drm_rect_rotate(&frame_info->rotated, drm_rect_width(&frame_info->rotated),
+			drm_rect_height(&frame_info->rotated), frame_info->rotation);
+
 	frame_info->offset = fb->offsets[0];
 	frame_info->pitch = fb->pitches[0];
 	frame_info->cpp = fb->format->cpp[0];
@@ -201,5 +209,9 @@ struct vkms_plane *vkms_plane_init(struct vkms_device *vkmsdev,
 
 	drm_plane_helper_add(&plane->base, &vkms_plane_helper_funcs);
 
+	drm_plane_create_rotation_property(&plane->base, DRM_MODE_ROTATE_0,
+					   DRM_MODE_ROTATE_0 |
+					   DRM_MODE_REFLECT_X);
+
 	return plane;
 }