drm/vkms: Create helpers macro to avoid code duplication in format callbacks

The callback functions for line conversion are almost identical for
some format. The generic READ_LINE macro generate all the required
boilerplate to process a line.

Two overrides of this macro have been added to avoid duplication of
the same arguments every time.

Reviewed-by: Maíra Canal <mcanal@igalia.com>
Acked-by: Daniel Stone <daniels@collabora.com>
Link: https://lore.kernel.org/r/20250703-b4-new-color-formats-v7-1-15fd8fd2e15c@bootlin.com
Signed-off-by: Louis Chauvet <louis.chauvet@bootlin.com>

Author: Fomys

drivers/gpu/drm/vkms/vkms_formats.c

@@ -292,6 +292,64 @@ VISIBLE_IF_KUNIT struct pixel_argb_u16 argb_u16_from_yuv888(u8 y, u8 channel_1,
 }
 EXPORT_SYMBOL_IF_KUNIT(argb_u16_from_yuv888);
 
+/**
+ * READ_LINE() - Generic generator for a read_line function which can be used for format with one
+ * plane and a block_h == block_w == 1.
+ *
+ * @function_name: Function name to generate
+ * @pixel_name: Temporary pixel name used in the @__VA_ARGS__ parameters
+ * @pixel_type: Used to specify the type you want to cast the pixel pointer
+ * @callback: Callback to call for each pixels. This fonction should take @__VA_ARGS__ as parameter
+ *            and return a pixel_argb_u16
+ * __VA_ARGS__: Argument to pass inside the callback. You can use @pixel_name to access current
+ *  pixel.
+ */
+#define READ_LINE(function_name, pixel_name, pixel_type, callback, ...)				\
+static void function_name(const struct vkms_plane_state *plane, int x_start,			\
+			      int y_start, enum pixel_read_direction direction, int count,	\
+			      struct pixel_argb_u16 out_pixel[])				\
+{												\
+	struct pixel_argb_u16 *end = out_pixel + count;						\
+	int step = get_block_step_bytes(plane->frame_info->fb, direction, 0);			\
+	u8 *src_pixels;										\
+												\
+	packed_pixels_addr_1x1(plane->frame_info, x_start, y_start, 0, &src_pixels);		\
+												\
+	while (out_pixel < end) {								\
+		pixel_type *(pixel_name) = (pixel_type *)src_pixels;				\
+		*out_pixel = (callback)(__VA_ARGS__);						\
+		out_pixel += 1;									\
+		src_pixels += step;								\
+	}											\
+}
+
+/**
+ * READ_LINE_ARGB8888() - Generic generator for ARGB8888 formats.
+ * The pixel type used is u8, so pixel_name[0]..pixel_name[n] are the n components of the pixel.
+ *
+ * @function_name: Function name to generate
+ * @pixel_name: temporary pixel to use in @a, @r, @g and @b parameters
+ * @a: alpha value
+ * @r: red value
+ * @g: green value
+ * @b: blue value
+ */
+#define READ_LINE_ARGB8888(function_name, pixel_name, a, r, g, b) \
+	READ_LINE(function_name, pixel_name, u8, argb_u16_from_u8888, a, r, g, b)
+/**
+ * READ_LINE_le16161616() - Generic generator for ARGB16161616 formats.
+ * The pixel type used is u16, so pixel_name[0]..pixel_name[n] are the n components of the pixel.
+ *
+ * @function_name: Function name to generate
+ * @pixel_name: temporary pixel to use in @a, @r, @g and @b parameters
+ * @a: alpha value
+ * @r: red value
+ * @g: green value
+ * @b: blue value
+ */
+#define READ_LINE_le16161616(function_name, pixel_name, a, r, g, b) \
+	READ_LINE(function_name, pixel_name, __le16, argb_u16_from_le16161616, a, r, g, b)
+
 /*
  * The following functions are read_line function for each pixel format supported by VKMS.
  *
@@ -378,138 +436,18 @@ static void R4_read_line(const struct vkms_plane_state *plane, int x_start,
 	Rx_read_line(plane, x_start, y_start, direction, count, out_pixel);
 }
 
-static void R8_read_line(const struct vkms_plane_state *plane, int x_start,
-			 int y_start, enum pixel_read_direction direction, int count,
-			 struct pixel_argb_u16 out_pixel[])
-{
-	struct pixel_argb_u16 *end = out_pixel + count;
-	u8 *src_pixels;
-	int step = get_block_step_bytes(plane->frame_info->fb, direction, 0);
 
-	packed_pixels_addr_1x1(plane->frame_info, x_start, y_start, 0, &src_pixels);
+READ_LINE_ARGB8888(XRGB8888_read_line, px, 0xFF, px[2], px[1], px[0])
 
-	while (out_pixel < end) {
-		*out_pixel = argb_u16_from_gray8(*src_pixels);
-		src_pixels += step;
-		out_pixel += 1;
-	}
-}
+READ_LINE_ARGB8888(ARGB8888_read_line, px, px[3], px[2], px[1], px[0])
+READ_LINE_ARGB8888(ABGR8888_read_line, px, px[3], px[0], px[1], px[2])
 
-static void ARGB8888_read_line(const struct vkms_plane_state *plane, int x_start, int y_start,
-			       enum pixel_read_direction direction, int count,
-			       struct pixel_argb_u16 out_pixel[])
-{
-	struct pixel_argb_u16 *end = out_pixel + count;
-	u8 *src_pixels;
-
-	packed_pixels_addr_1x1(plane->frame_info, x_start, y_start, 0, &src_pixels);
+READ_LINE_le16161616(ARGB16161616_read_line, px, px[3], px[2], px[1], px[0])
+READ_LINE_le16161616(XRGB16161616_read_line, px, cpu_to_le16(0xFFFF), px[2], px[1], px[0])
 
-	int step = get_block_step_bytes(plane->frame_info->fb, direction, 0);
+READ_LINE(RGB565_read_line, px, __le16, argb_u16_from_RGB565, px)
 
-	while (out_pixel < end) {
-		u8 *px = (u8 *)src_pixels;
-		*out_pixel = argb_u16_from_u8888(px[3], px[2], px[1], px[0]);
-		out_pixel += 1;
-		src_pixels += step;
-	}
-}
-
-static void XRGB8888_read_line(const struct vkms_plane_state *plane, int x_start, int y_start,
-			       enum pixel_read_direction direction, int count,
-			       struct pixel_argb_u16 out_pixel[])
-{
-	struct pixel_argb_u16 *end = out_pixel + count;
-	u8 *src_pixels;
-
-	packed_pixels_addr_1x1(plane->frame_info, x_start, y_start, 0, &src_pixels);
-
-	int step = get_block_step_bytes(plane->frame_info->fb, direction, 0);
-
-	while (out_pixel < end) {
-		u8 *px = (u8 *)src_pixels;
-		*out_pixel = argb_u16_from_u8888(255, px[2], px[1], px[0]);
-		out_pixel += 1;
-		src_pixels += step;
-	}
-}
-
-static void ABGR8888_read_line(const struct vkms_plane_state *plane, int x_start, int y_start,
-			       enum pixel_read_direction direction, int count,
-			       struct pixel_argb_u16 out_pixel[])
-{
-	struct pixel_argb_u16 *end = out_pixel + count;
-	u8 *src_pixels;
-
-	packed_pixels_addr_1x1(plane->frame_info, x_start, y_start, 0, &src_pixels);
-
-	int step = get_block_step_bytes(plane->frame_info->fb, direction, 0);
-
-	while (out_pixel < end) {
-		u8 *px = (u8 *)src_pixels;
-		/* Switch blue and red pixels. */
-		*out_pixel = argb_u16_from_u8888(px[3], px[0], px[1], px[2]);
-		out_pixel += 1;
-		src_pixels += step;
-	}
-}
-
-static void ARGB16161616_read_line(const struct vkms_plane_state *plane, int x_start,
-				   int y_start, enum pixel_read_direction direction, int count,
-				   struct pixel_argb_u16 out_pixel[])
-{
-	struct pixel_argb_u16 *end = out_pixel + count;
-	u8 *src_pixels;
-
-	packed_pixels_addr_1x1(plane->frame_info, x_start, y_start, 0, &src_pixels);
-
-	int step = get_block_step_bytes(plane->frame_info->fb, direction, 0);
-
-	while (out_pixel < end) {
-		u16 *px = (u16 *)src_pixels;
-		*out_pixel = argb_u16_from_u16161616(px[3], px[2], px[1], px[0]);
-		out_pixel += 1;
-		src_pixels += step;
-	}
-}
-
-static void XRGB16161616_read_line(const struct vkms_plane_state *plane, int x_start,
-				   int y_start, enum pixel_read_direction direction, int count,
-				   struct pixel_argb_u16 out_pixel[])
-{
-	struct pixel_argb_u16 *end = out_pixel + count;
-	u8 *src_pixels;
-
-	packed_pixels_addr_1x1(plane->frame_info, x_start, y_start, 0, &src_pixels);
-
-	int step = get_block_step_bytes(plane->frame_info->fb, direction, 0);
-
-	while (out_pixel < end) {
-		__le16 *px = (__le16 *)src_pixels;
-		*out_pixel = argb_u16_from_le16161616(cpu_to_le16(0xFFFF), px[2], px[1], px[0]);
-		out_pixel += 1;
-		src_pixels += step;
-	}
-}
-
-static void RGB565_read_line(const struct vkms_plane_state *plane, int x_start,
-			     int y_start, enum pixel_read_direction direction, int count,
-			     struct pixel_argb_u16 out_pixel[])
-{
-	struct pixel_argb_u16 *end = out_pixel + count;
-	u8 *src_pixels;
-
-	packed_pixels_addr_1x1(plane->frame_info, x_start, y_start, 0, &src_pixels);
-
-	int step = get_block_step_bytes(plane->frame_info->fb, direction, 0);
-
-	while (out_pixel < end) {
-		__le16 *px = (__le16 *)src_pixels;
-
-		*out_pixel = argb_u16_from_RGB565(px);
-		out_pixel += 1;
-		src_pixels += step;
-	}
-}
+READ_LINE(R8_read_line, px, u8, argb_u16_from_gray8, *px)
 
 /*
  * This callback can be used for YUV formats where U and V values are