diff --git a/drivers/gpu/drm/vkms/vkms_drv.h b/drivers/gpu/drm/vkms/vkms_drv.h
index fcb5a5ff7df7123073f027d4773f1a515480441a..e0d46defed835e5670dc1665da9917f807ad0c07 100644
--- a/drivers/gpu/drm/vkms/vkms_drv.h
+++ b/drivers/gpu/drm/vkms/vkms_drv.h
@@ -53,12 +53,31 @@ struct line_buffer {
 	struct pixel_argb_u16 *pixels;
 };
 
+/**
+ * typedef pixel_write_t - These functions are used to read a pixel from a
+ * &struct pixel_argb_u16, convert it in a specific format and write it in the @out_pixel
+ * buffer.
+ *
+ * @out_pixel: destination address to write the pixel
+ * @in_pixel: pixel to write
+ */
+typedef void (*pixel_write_t)(u8 *out_pixel, struct pixel_argb_u16 *in_pixel);
+
 struct vkms_writeback_job {
 	struct iosys_map data[DRM_FORMAT_MAX_PLANES];
 	struct vkms_frame_info wb_frame_info;
-	void (*pixel_write)(u8 *dst_pixels, struct pixel_argb_u16 *in_pixel);
+	pixel_write_t pixel_write;
 };
 
+/**
+ * typedef pixel_read_t - These functions are used to read a pixel in the source frame,
+ * convert it to `struct pixel_argb_u16` and write it to @out_pixel.
+ *
+ * @in_pixel: pointer to the pixel to read
+ * @out_pixel: pointer to write the converted pixel
+ */
+typedef void (*pixel_read_t)(u8 *in_pixel, struct pixel_argb_u16 *out_pixel);
+
 /**
  * struct vkms_plane_state - Driver specific plane state
  * @base: base plane state
@@ -69,7 +88,7 @@ struct vkms_writeback_job {
 struct vkms_plane_state {
 	struct drm_shadow_plane_state base;
 	struct vkms_frame_info *frame_info;
-	void (*pixel_read)(u8 *src_buffer, struct pixel_argb_u16 *out_pixel);
+	pixel_read_t pixel_read;
 };
 
 struct vkms_plane {
diff --git a/drivers/gpu/drm/vkms/vkms_formats.c b/drivers/gpu/drm/vkms/vkms_formats.c
index 2a0fbe27d8b28e7e9e8a12ad08a2cac4ba7277e7..b9544e67cd4fad7fdd4707527a6ff8ea8f2c35be 100644
--- a/drivers/gpu/drm/vkms/vkms_formats.c
+++ b/drivers/gpu/drm/vkms/vkms_formats.c
@@ -75,7 +75,7 @@ static int get_x_position(const struct vkms_frame_info *frame_info, int limit, i
  * They are used in the vkms_compose_row() function to handle multiple formats.
  */
 
-static void ARGB8888_to_argb_u16(u8 *src_pixels, struct pixel_argb_u16 *out_pixel)
+static void ARGB8888_to_argb_u16(u8 *in_pixel, struct pixel_argb_u16 *out_pixel)
 {
 	/*
 	 * The 257 is the "conversion ratio". This number is obtained by the
@@ -83,48 +83,48 @@ static void ARGB8888_to_argb_u16(u8 *src_pixels, struct pixel_argb_u16 *out_pixe
 	 * the best color value in a pixel format with more possibilities.
 	 * A similar idea applies to others RGB color conversions.
 	 */
-	out_pixel->a = (u16)src_pixels[3] * 257;
-	out_pixel->r = (u16)src_pixels[2] * 257;
-	out_pixel->g = (u16)src_pixels[1] * 257;
-	out_pixel->b = (u16)src_pixels[0] * 257;
+	out_pixel->a = (u16)in_pixel[3] * 257;
+	out_pixel->r = (u16)in_pixel[2] * 257;
+	out_pixel->g = (u16)in_pixel[1] * 257;
+	out_pixel->b = (u16)in_pixel[0] * 257;
 }
 
-static void XRGB8888_to_argb_u16(u8 *src_pixels, struct pixel_argb_u16 *out_pixel)
+static void XRGB8888_to_argb_u16(u8 *in_pixel, struct pixel_argb_u16 *out_pixel)
 {
 	out_pixel->a = (u16)0xffff;
-	out_pixel->r = (u16)src_pixels[2] * 257;
-	out_pixel->g = (u16)src_pixels[1] * 257;
-	out_pixel->b = (u16)src_pixels[0] * 257;
+	out_pixel->r = (u16)in_pixel[2] * 257;
+	out_pixel->g = (u16)in_pixel[1] * 257;
+	out_pixel->b = (u16)in_pixel[0] * 257;
 }
 
-static void ARGB16161616_to_argb_u16(u8 *src_pixels, struct pixel_argb_u16 *out_pixel)
+static void ARGB16161616_to_argb_u16(u8 *in_pixel, struct pixel_argb_u16 *out_pixel)
 {
-	__le16 *pixels = (__force __le16 *)src_pixels;
+	__le16 *pixel = (__le16 *)in_pixel;
 
-	out_pixel->a = le16_to_cpu(pixels[3]);
-	out_pixel->r = le16_to_cpu(pixels[2]);
-	out_pixel->g = le16_to_cpu(pixels[1]);
-	out_pixel->b = le16_to_cpu(pixels[0]);
+	out_pixel->a = le16_to_cpu(pixel[3]);
+	out_pixel->r = le16_to_cpu(pixel[2]);
+	out_pixel->g = le16_to_cpu(pixel[1]);
+	out_pixel->b = le16_to_cpu(pixel[0]);
 }
 
-static void XRGB16161616_to_argb_u16(u8 *src_pixels, struct pixel_argb_u16 *out_pixel)
+static void XRGB16161616_to_argb_u16(u8 *in_pixel, struct pixel_argb_u16 *out_pixel)
 {
-	__le16 *pixels = (__force __le16 *)src_pixels;
+	__le16 *pixel = (__le16 *)in_pixel;
 
 	out_pixel->a = (u16)0xffff;
-	out_pixel->r = le16_to_cpu(pixels[2]);
-	out_pixel->g = le16_to_cpu(pixels[1]);
-	out_pixel->b = le16_to_cpu(pixels[0]);
+	out_pixel->r = le16_to_cpu(pixel[2]);
+	out_pixel->g = le16_to_cpu(pixel[1]);
+	out_pixel->b = le16_to_cpu(pixel[0]);
 }
 
-static void RGB565_to_argb_u16(u8 *src_pixels, struct pixel_argb_u16 *out_pixel)
+static void RGB565_to_argb_u16(u8 *in_pixel, struct pixel_argb_u16 *out_pixel)
 {
-	__le16 *pixels = (__force __le16 *)src_pixels;
+	__le16 *pixel = (__le16 *)in_pixel;
 
 	s64 fp_rb_ratio = drm_fixp_div(drm_int2fixp(65535), drm_int2fixp(31));
 	s64 fp_g_ratio = drm_fixp_div(drm_int2fixp(65535), drm_int2fixp(63));
 
-	u16 rgb_565 = le16_to_cpu(*pixels);
+	u16 rgb_565 = le16_to_cpu(*pixel);
 	s64 fp_r = drm_int2fixp((rgb_565 >> 11) & 0x1f);
 	s64 fp_g = drm_int2fixp((rgb_565 >> 5) & 0x3f);
 	s64 fp_b = drm_int2fixp(rgb_565 & 0x1f);
@@ -168,12 +168,12 @@ void vkms_compose_row(struct line_buffer *stage_buffer, struct vkms_plane_state
 
 /*
  * The following functions take one &struct pixel_argb_u16 and convert it to a specific format.
- * The result is stored in @dst_pixels.
+ * The result is stored in @out_pixel.
  *
  * They are used in vkms_writeback_row() to convert and store a pixel from the src_buffer to
  * the writeback buffer.
  */
-static void argb_u16_to_ARGB8888(u8 *dst_pixels, struct pixel_argb_u16 *in_pixel)
+static void argb_u16_to_ARGB8888(u8 *out_pixel, struct pixel_argb_u16 *in_pixel)
 {
 	/*
 	 * This sequence below is important because the format's byte order is
@@ -185,43 +185,43 @@ static void argb_u16_to_ARGB8888(u8 *dst_pixels, struct pixel_argb_u16 *in_pixel
 	 * | Addr + 2 | = Red channel
 	 * | Addr + 3 | = Alpha channel
 	 */
-	dst_pixels[3] = DIV_ROUND_CLOSEST(in_pixel->a, 257);
-	dst_pixels[2] = DIV_ROUND_CLOSEST(in_pixel->r, 257);
-	dst_pixels[1] = DIV_ROUND_CLOSEST(in_pixel->g, 257);
-	dst_pixels[0] = DIV_ROUND_CLOSEST(in_pixel->b, 257);
+	out_pixel[3] = DIV_ROUND_CLOSEST(in_pixel->a, 257);
+	out_pixel[2] = DIV_ROUND_CLOSEST(in_pixel->r, 257);
+	out_pixel[1] = DIV_ROUND_CLOSEST(in_pixel->g, 257);
+	out_pixel[0] = DIV_ROUND_CLOSEST(in_pixel->b, 257);
 }
 
-static void argb_u16_to_XRGB8888(u8 *dst_pixels, struct pixel_argb_u16 *in_pixel)
+static void argb_u16_to_XRGB8888(u8 *out_pixel, struct pixel_argb_u16 *in_pixel)
 {
-	dst_pixels[3] = 0xff;
-	dst_pixels[2] = DIV_ROUND_CLOSEST(in_pixel->r, 257);
-	dst_pixels[1] = DIV_ROUND_CLOSEST(in_pixel->g, 257);
-	dst_pixels[0] = DIV_ROUND_CLOSEST(in_pixel->b, 257);
+	out_pixel[3] = 0xff;
+	out_pixel[2] = DIV_ROUND_CLOSEST(in_pixel->r, 257);
+	out_pixel[1] = DIV_ROUND_CLOSEST(in_pixel->g, 257);
+	out_pixel[0] = DIV_ROUND_CLOSEST(in_pixel->b, 257);
 }
 
-static void argb_u16_to_ARGB16161616(u8 *dst_pixels, struct pixel_argb_u16 *in_pixel)
+static void argb_u16_to_ARGB16161616(u8 *out_pixel, struct pixel_argb_u16 *in_pixel)
 {
-	__le16 *pixels = (__force __le16 *)dst_pixels;
+	__le16 *pixel = (__le16 *)out_pixel;
 
-	pixels[3] = cpu_to_le16(in_pixel->a);
-	pixels[2] = cpu_to_le16(in_pixel->r);
-	pixels[1] = cpu_to_le16(in_pixel->g);
-	pixels[0] = cpu_to_le16(in_pixel->b);
+	pixel[3] = cpu_to_le16(in_pixel->a);
+	pixel[2] = cpu_to_le16(in_pixel->r);
+	pixel[1] = cpu_to_le16(in_pixel->g);
+	pixel[0] = cpu_to_le16(in_pixel->b);
 }
 
-static void argb_u16_to_XRGB16161616(u8 *dst_pixels, struct pixel_argb_u16 *in_pixel)
+static void argb_u16_to_XRGB16161616(u8 *out_pixel, struct pixel_argb_u16 *in_pixel)
 {
-	__le16 *pixels = (__force __le16 *)dst_pixels;
+	__le16 *pixel = (__le16 *)out_pixel;
 
-	pixels[3] = cpu_to_le16(0xffff);
-	pixels[2] = cpu_to_le16(in_pixel->r);
-	pixels[1] = cpu_to_le16(in_pixel->g);
-	pixels[0] = cpu_to_le16(in_pixel->b);
+	pixel[3] = cpu_to_le16(0xffff);
+	pixel[2] = cpu_to_le16(in_pixel->r);
+	pixel[1] = cpu_to_le16(in_pixel->g);
+	pixel[0] = cpu_to_le16(in_pixel->b);
 }
 
-static void argb_u16_to_RGB565(u8 *dst_pixels, struct pixel_argb_u16 *in_pixel)
+static void argb_u16_to_RGB565(u8 *out_pixel, struct pixel_argb_u16 *in_pixel)
 {
-	__le16 *pixels = (__force __le16 *)dst_pixels;
+	__le16 *pixel = (__le16 *)out_pixel;
 
 	s64 fp_rb_ratio = drm_fixp_div(drm_int2fixp(65535), drm_int2fixp(31));
 	s64 fp_g_ratio = drm_fixp_div(drm_int2fixp(65535), drm_int2fixp(63));
@@ -234,7 +234,7 @@ static void argb_u16_to_RGB565(u8 *dst_pixels, struct pixel_argb_u16 *in_pixel)
 	u16 g = drm_fixp2int(drm_fixp_div(fp_g, fp_g_ratio));
 	u16 b = drm_fixp2int(drm_fixp_div(fp_b, fp_rb_ratio));
 
-	*pixels = cpu_to_le16(r << 11 | g << 5 | b);
+	*pixel = cpu_to_le16(r << 11 | g << 5 | b);
 }
 
 /**
@@ -259,13 +259,13 @@ void vkms_writeback_row(struct vkms_writeback_job *wb,
 }
 
 /**
- * get_pixel_conversion_function() - Retrieve the correct read_pixel function for a specific
+ * get_pixel_read_function() - Retrieve the correct read_pixel function for a specific
  * format. The returned pointer is NULL for unsupported pixel formats. The caller must ensure that
  * the pointer is valid before using it in a vkms_plane_state.
  *
  * @format: DRM_FORMAT_* value for which to obtain a conversion function (see [drm_fourcc.h])
  */
-void *get_pixel_conversion_function(u32 format)
+pixel_read_t get_pixel_read_function(u32 format)
 {
 	switch (format) {
 	case DRM_FORMAT_ARGB8888:
@@ -279,7 +279,15 @@ void *get_pixel_conversion_function(u32 format)
 	case DRM_FORMAT_RGB565:
 		return &RGB565_to_argb_u16;
 	default:
-		return NULL;
+		/*
+		 * This is a bug in vkms_plane_atomic_check(). All the supported
+		 * format must:
+		 * - Be listed in vkms_formats in vkms_plane.c
+		 * - Have a pixel_read callback defined here
+		 */
+		pr_err("Pixel format %p4cc is not supported by VKMS planes. This is a kernel bug, atomic check must forbid this configuration.\n",
+		       &format);
+		BUG();
 	}
 }
 
@@ -290,7 +298,7 @@ void *get_pixel_conversion_function(u32 format)
  *
  * @format: DRM_FORMAT_* value for which to obtain a conversion function (see [drm_fourcc.h])
  */
-void *get_pixel_write_function(u32 format)
+pixel_write_t get_pixel_write_function(u32 format)
 {
 	switch (format) {
 	case DRM_FORMAT_ARGB8888:
@@ -304,6 +312,14 @@ void *get_pixel_write_function(u32 format)
 	case DRM_FORMAT_RGB565:
 		return &argb_u16_to_RGB565;
 	default:
-		return NULL;
+		/*
+		 * This is a bug in vkms_writeback_atomic_check. All the supported
+		 * format must:
+		 * - Be listed in vkms_wb_formats in vkms_writeback.c
+		 * - Have a pixel_write callback defined here
+		 */
+		pr_err("Pixel format %p4cc is not supported by VKMS writeback. This is a kernel bug, atomic check must forbid this configuration.\n",
+		       &format);
+		BUG();
 	}
 }
diff --git a/drivers/gpu/drm/vkms/vkms_formats.h b/drivers/gpu/drm/vkms/vkms_formats.h
index cf59c2ed8e9af06c9838635e3f7819a9169494b5..3ecea456325490f41fecf35ba2db2676252013a6 100644
--- a/drivers/gpu/drm/vkms/vkms_formats.h
+++ b/drivers/gpu/drm/vkms/vkms_formats.h
@@ -5,8 +5,8 @@
 
 #include "vkms_drv.h"
 
-void *get_pixel_conversion_function(u32 format);
+pixel_read_t get_pixel_read_function(u32 format);
 
-void *get_pixel_write_function(u32 format);
+pixel_write_t get_pixel_write_function(u32 format);
 
 #endif /* _VKMS_FORMATS_H_ */
diff --git a/drivers/gpu/drm/vkms/vkms_plane.c b/drivers/gpu/drm/vkms/vkms_plane.c
index 21b5adfb44aa584e1acd6697954aabeb4e905c3c..10e9b23dab28359235ee0375aa195fc2a4abda73 100644
--- a/drivers/gpu/drm/vkms/vkms_plane.c
+++ b/drivers/gpu/drm/vkms/vkms_plane.c
@@ -125,7 +125,7 @@ static void vkms_plane_atomic_update(struct drm_plane *plane,
 	drm_rect_rotate(&frame_info->rotated, drm_rect_width(&frame_info->rotated),
 			drm_rect_height(&frame_info->rotated), frame_info->rotation);
 
-	vkms_plane_state->pixel_read = get_pixel_conversion_function(fmt);
+	vkms_plane_state->pixel_read = get_pixel_read_function(fmt);
 }
 
 static int vkms_plane_atomic_check(struct drm_plane *plane,
