drm/format-helper: Add conversion from XRGB8888 to ARGB8888

Add dedicated helper to convert from XRGB8888 to ARGB8888. Sets
all alpha bits to make pixels fully opaque.

v3:
	* use __le32 for destination buffer (Jose, kernel test robot)
v2:
	* 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/20230102112927.26565-8-tzimmermann@suse.de

1 files changed, 51 insertions, 2 deletions

diff --git a/drivers/gpu/drm/drm_format_helper.c b/drivers/gpu/drm/drm_format_helper.c
index 36d2ca9d0f01..718e29341773 100644
--- a/drivers/gpu/drm/drm_format_helper.c
+++ b/drivers/gpu/drm/drm_format_helper.c
@@ -446,6 +446,54 @@ void drm_fb_xrgb8888_to_rgb888(struct iosys_map *dst, const unsigned int *dst_pi
 }
 EXPORT_SYMBOL(drm_fb_xrgb8888_to_rgb888);
 
+static void drm_fb_xrgb8888_to_argb8888_line(void *dbuf, const void *sbuf, unsigned int pixels)
+{
+	__le32 *dbuf32 = dbuf;
+	const __le32 *sbuf32 = sbuf;
+	unsigned int x;
+	u32 pix;
+
+	for (x = 0; x < pixels; x++) {
+		pix = le32_to_cpu(sbuf32[x]);
+		pix |= GENMASK(31, 24); /* fill alpha bits */
+		dbuf32[x] = cpu_to_le32(pix);
+	}
+}
+
+/**
+ * drm_fb_xrgb8888_to_argb8888 - Convert XRGB8888 to ARGB8888 clip buffer
+ * @dst: Array of ARGB8888 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 buffer
+ * @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 ARGB8888 devices that don't support XRGB8888
+ * natively. It sets an opaque alpha channel as part of the conversion.
+ */
+void drm_fb_xrgb8888_to_argb8888(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_argb8888_line);
+}
+EXPORT_SYMBOL(drm_fb_xrgb8888_to_argb8888);
+
 static void drm_fb_rgb565_to_xrgb8888_line(void *dbuf, const void *sbuf, unsigned int pixels)
 {
 	__le32 *dbuf32 = dbuf;
@@ -646,8 +694,6 @@ int drm_fb_blit(struct iosys_map *dst, const unsigned int *dst_pitch, uint32_t d
 	/* treat alpha channel like filler bits */
 	if (fb_format == DRM_FORMAT_ARGB8888)
 		fb_format = DRM_FORMAT_XRGB8888;
-	if (dst_format == DRM_FORMAT_ARGB8888)
-		dst_format = DRM_FORMAT_XRGB8888;
 	if (fb_format == DRM_FORMAT_ARGB2101010)
 		fb_format = DRM_FORMAT_XRGB2101010;
 	if (dst_format == DRM_FORMAT_ARGB2101010)
@@ -669,6 +715,9 @@ int drm_fb_blit(struct iosys_map *dst, const unsigned int *dst_pitch, uint32_t d
 		} else if (dst_format == DRM_FORMAT_RGB888) {
 			drm_fb_xrgb8888_to_rgb888(dst, dst_pitch, src, fb, clip);
 			return 0;
+		} else if (dst_format == DRM_FORMAT_ARGB8888) {
+			drm_fb_xrgb8888_to_argb8888(dst, dst_pitch, src, fb, clip);
+			return 0;
 		} else if (dst_format == DRM_FORMAT_XRGB2101010) {
 			drm_fb_xrgb8888_to_xrgb2101010(dst, dst_pitch, src, fb, clip);
 			return 0;