drm/format-helper: Add conversion from XRGB8888 to ARGB2101010

Add dedicated helper to convert from XRGB8888 to ARGB2101010. Sets
all alpha bits to make pixels fully opaque.

v2:
	* set correct format in struct drm_framebuffer (Javier)
	* use cpubuf_to_le32()
	* type fixes

Signed-off-by: Thomas Zimmermann <tzimmermann@suse.de>
Reviewed-by: Javier Martinez Canillas <javierm@redhat.com>
Reviewed-by: José Expósito <jose.exposito89@gmail.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20230102112927.26565-9-tzimmermann@suse.de

1 files changed, 56 insertions, 2 deletions

diff --git a/drivers/gpu/drm/drm_format_helper.c b/drivers/gpu/drm/drm_format_helper.c
index 718e29341773..33780c9183bb 100644
--- a/drivers/gpu/drm/drm_format_helper.c
+++ b/drivers/gpu/drm/drm_format_helper.c
@@ -605,6 +605,59 @@ void drm_fb_xrgb8888_to_xrgb2101010(struct iosys_map *dst, const unsigned int *d
 }
 EXPORT_SYMBOL(drm_fb_xrgb8888_to_xrgb2101010);
 
+static void drm_fb_xrgb8888_to_argb2101010_line(void *dbuf, const void *sbuf, unsigned int pixels)
+{
+	__le32 *dbuf32 = dbuf;
+	const __le32 *sbuf32 = sbuf;
+	unsigned int x;
+	u32 val32;
+	u32 pix;
+
+	for (x = 0; x < pixels; x++) {
+		pix = le32_to_cpu(sbuf32[x]);
+		val32 = ((pix & 0x000000ff) << 2) |
+			((pix & 0x0000ff00) << 4) |
+			((pix & 0x00ff0000) << 6);
+		pix = GENMASK(31, 30) | /* set alpha bits */
+		      val32 | ((val32 >> 8) & 0x00300c03);
+		*dbuf32++ = cpu_to_le32(pix);
+	}
+}
+
+/**
+ * drm_fb_xrgb8888_to_argb2101010 - Convert XRGB8888 to ARGB2101010 clip buffer
+ * @dst: Array of ARGB2101010 destination buffers
+ * @dst_pitch: Array of numbers of bytes between the start of two consecutive scanlines
+ *             within @dst; can be NULL if scanlines are stored next to each other.
+ * @src: Array of XRGB8888 source buffers
+ * @fb: DRM framebuffer
+ * @clip: Clip rectangle area to copy
+ *
+ * This function copies parts of a framebuffer to display memory and converts
+ * the color format during the process. The parameters @dst, @dst_pitch and
+ * @src refer to arrays. Each array must have at least as many entries as
+ * there are planes in @fb's format. Each entry stores the value for the
+ * format's respective color plane at the same index.
+ *
+ * This function does not apply clipping on @dst (i.e. the destination is at the
+ * top-left corner).
+ *
+ * Drivers can use this function for ARGB2101010 devices that don't support XRGB8888
+ * natively.
+ */
+void drm_fb_xrgb8888_to_argb2101010(struct iosys_map *dst, const unsigned int *dst_pitch,
+				    const struct iosys_map *src, const struct drm_framebuffer *fb,
+				    const struct drm_rect *clip)
+{
+	static const u8 dst_pixsize[DRM_FORMAT_MAX_PLANES] = {
+		4,
+	};
+
+	drm_fb_xfrm(dst, dst_pitch, dst_pixsize, src, fb, clip, false,
+		    drm_fb_xrgb8888_to_argb2101010_line);
+}
+EXPORT_SYMBOL(drm_fb_xrgb8888_to_argb2101010);
+
 static void drm_fb_xrgb8888_to_gray8_line(void *dbuf, const void *sbuf, unsigned int pixels)
 {
 	u8 *dbuf8 = dbuf;
@@ -696,8 +749,6 @@ int drm_fb_blit(struct iosys_map *dst, const unsigned int *dst_pitch, uint32_t d
 		fb_format = DRM_FORMAT_XRGB8888;
 	if (fb_format == DRM_FORMAT_ARGB2101010)
 		fb_format = DRM_FORMAT_XRGB2101010;
-	if (dst_format == DRM_FORMAT_ARGB2101010)
-		dst_format = DRM_FORMAT_XRGB2101010;
 
 	if (fb_format == dst_format) {
 		drm_fb_memcpy(dst, dst_pitch, src, fb, clip);
@@ -721,6 +772,9 @@ int drm_fb_blit(struct iosys_map *dst, const unsigned int *dst_pitch, uint32_t d
 		} else if (dst_format == DRM_FORMAT_XRGB2101010) {
 			drm_fb_xrgb8888_to_xrgb2101010(dst, dst_pitch, src, fb, clip);
 			return 0;
+		} else if (dst_format == DRM_FORMAT_ARGB2101010) {
+			drm_fb_xrgb8888_to_argb2101010(dst, dst_pitch, src, fb, clip);
+			return 0;
 		} else if (dst_format == DRM_FORMAT_BGRX8888) {
 			drm_fb_swab(dst, dst_pitch, src, fb, clip, false);
 			return 0;