On 1/6/2026 8:25 AM, Francesco Valla wrote:
Add a DRM client that draws a simple splash, with possibility to show:

   - a colored background;
   - a static BMP image (loaded as firmware);
   - the logo provided by EFI BGRT.

That's cool, thanks for implementing my suggestion!


The client is not meant to replace a full-featured bootsplash, but
rather to remove some complexity (and hopefully boot time) on small
embedded platforms or on systems with a limited scope (e.g: recovery
or manufacturing images).

In theory when using EFI BGRT you could:
* have the BIOS show the BGRT
* bootloader not show anything
* kernel overwrite the framebuffer containing the BIOS BGRT with the exact same image (should be invisible to the user) * regular bootsplash like plymouth overwrite the framebuffer again with the same BGRT but then also add progress bar/distro logo etc.


The background color can be set either at build time from a dedicated
config option or at runtime through the drm_client_lib.splash_color
command line parameter. Any color in RGB888 format can be used.

If enabled, the static BMP image is loaded using the kernel firmware
infrastructure; a valid BMP image with 24bpp color and no compression
is expected. The name of the image can be set through the
drm_client_lib.splash_bmp kernel command line parameter, with the
default being 'drm_splash.bmp'.

Just like the existing DRM clients, the splash can be enabled from the
kernel command line using drm_client_lib.active=splash.

Signed-off-by: Francesco Valla <[email protected]>
---
  drivers/gpu/drm/clients/Kconfig               |  79 ++-
  drivers/gpu/drm/clients/Makefile              |   1 +
  drivers/gpu/drm/clients/drm_client_internal.h |   9 +
  drivers/gpu/drm/clients/drm_client_setup.c    |   8 +
  drivers/gpu/drm/clients/drm_splash.c          | 883 ++++++++++++++++++++++++++
  5 files changed, 979 insertions(+), 1 deletion(-)

diff --git a/drivers/gpu/drm/clients/Kconfig b/drivers/gpu/drm/clients/Kconfig
index 
6096c623d9d5b1a3d4a40d986c45aad2f8277767..dd8cd6cacd1166932eb3890dd816b9ae2d26330f
 100644
--- a/drivers/gpu/drm/clients/Kconfig
+++ b/drivers/gpu/drm/clients/Kconfig
@@ -12,6 +12,7 @@ config DRM_CLIENT_LIB
  config DRM_CLIENT_SELECTION
        tristate
        depends on DRM
+       select DRM_CLIENT_LIB if DRM_CLIENT_SPLASH
        select DRM_CLIENT_LIB if DRM_CLIENT_LOG
        select DRM_CLIENT_LIB if DRM_FBDEV_EMULATION
        help
@@ -85,10 +86,79 @@ config DRM_CLIENT_LOG
          If you only need logs, but no terminal, or if you prefer userspace
          terminal, say "Y".
+config DRM_CLIENT_SPLASH
+       bool "Display graphic splash"
+       depends on DRM_CLIENT_SELECTION
+       select DRM_CLIENT
+       select DRM_CLIENT_SETUP
+       select DRM_DRAW
+       help
+         This enables a splash drm client, able to display either a plain
+         color or a static image until the userspace is ready to take over.
+         The splash will be displayed on all screens available at boot, if
+         any, or on the ones part of the first hotplug event.
+
+config DRM_CLIENT_SPLASH_BACKGROUND_COLOR
+       hex "Splash background color"
+       depends on DRM_CLIENT_SPLASH
+       default 0x000000
+       help
+         The default splash background color, in RGB888 format.
+
+         The color can be overridden through the drm_client_lib.splash_color
+         kernel command line parameter.
+
+config DRM_CLIENT_SPLASH_BMP_SUPPORT
+       bool
+
+choice
+       prompt "Splash source"
+       depends on DRM_CLIENT_SPLASH
+       default DRM_CLIENT_SPLASH_SRC_COLOR
+       help
+         Selects the source for the splash graphic.
+
+config DRM_CLIENT_SPLASH_SRC_COLOR
+       bool "Solid color"
+       help
+         Use a solid color as splash. The color is selected through the
+         DRM_CLIENT_SPLASH_BACKGROUND_COLOR config option.
+
+         The image will be loaded using the firmware loading facility the
+         kernel provides.
+
+config DRM_CLIENT_SPLASH_SRC_BMP
+       bool "BMP image"
+       select DRM_CLIENT_SPLASH_BMP_SUPPORT
+       select FW_LOADER
+       help
+         Use a BMP (bitmap) image as splash. If the image is smaller than the
+         display(s), it will be centered and the color specified through the
+         DRM_CLIENT_SPLASH_BACKGROUND_COLOR config option will be used as
+         background.
+
+         The image will be loaded using the firmware loading facility the
+         kernel provides; it shall use 24 bits per pixel and shall not be
+         compressed. The name of the file can be set through the
+         drm_client_lib.splash_bmp command line parameter, with the default
+         being 'drm_splash.bmp'.
+
+config DRM_CLIENT_SPLASH_SRC_BGRT
+       bool "EFI BGRT"
+       select DRM_CLIENT_SPLASH_BMP_SUPPORT
+       depends on EFI
+       help
+         Use the BGRT image provided by the EFI bootloader. If the image is
+         smaller than the display(s), it will be centered and the color
+         specified through the DRM_CLIENT_SPLASH_BACKGROUND_COLOR config
+         option will be used as background.
+
+endchoice
+
  choice
        prompt "Default DRM Client"
        depends on DRM_CLIENT_SELECTION
-       depends on DRM_FBDEV_EMULATION || DRM_CLIENT_LOG
+       depends on DRM_FBDEV_EMULATION || DRM_CLIENT_LOG || DRM_CLIENT_SPLASH
        default DRM_CLIENT_DEFAULT_FBDEV
        help
          Selects the default drm client.
@@ -111,6 +181,12 @@ config DRM_CLIENT_DEFAULT_LOG
          screen, but doesn't implement a full terminal. For that you will need
          a userspace terminal using drm/kms.
+config DRM_CLIENT_DEFAULT_SPLASH
+       bool "splash"
+       depends on DRM_CLIENT_SPLASH
+       help
+         Use splash as default drm client.
+
  endchoice
config DRM_CLIENT_DEFAULT
@@ -118,6 +194,7 @@ config DRM_CLIENT_DEFAULT
         depends on DRM_CLIENT
         default "fbdev" if DRM_CLIENT_DEFAULT_FBDEV
         default "log" if DRM_CLIENT_DEFAULT_LOG
+       default "splash" if DRM_CLIENT_DEFAULT_SPLASH

Whitespace off by a character?

         default ""
endmenu
diff --git a/drivers/gpu/drm/clients/Makefile b/drivers/gpu/drm/clients/Makefile
index 
c16addbc327f09572aa3142cbf0d1d13f172a9e9..3df02d10cd18a47d7e8d7cee70163b0ef0129b51
 100644
--- a/drivers/gpu/drm/clients/Makefile
+++ b/drivers/gpu/drm/clients/Makefile
@@ -5,4 +5,5 @@ subdir-ccflags-y += -I$(src)/..
  drm_client_lib-y := drm_client_setup.o
  drm_client_lib-$(CONFIG_DRM_CLIENT_LOG) += drm_log.o
  drm_client_lib-$(CONFIG_DRM_FBDEV_EMULATION) += drm_fbdev_client.o
+drm_client_lib-$(CONFIG_DRM_CLIENT_SPLASH) += drm_splash.o
  obj-$(CONFIG_DRM_CLIENT_LIB) += drm_client_lib.o
diff --git a/drivers/gpu/drm/clients/drm_client_internal.h 
b/drivers/gpu/drm/clients/drm_client_internal.h
index 
6dc078bf6503b902cbb3267b64ea42d9f1c23375..48ee0c1c2529882b2bf5dc786788390823e25cd6
 100644
--- a/drivers/gpu/drm/clients/drm_client_internal.h
+++ b/drivers/gpu/drm/clients/drm_client_internal.h
@@ -22,4 +22,13 @@ void drm_log_register(struct drm_device *dev);
  static inline void drm_log_register(struct drm_device *dev) {}
  #endif
+#ifdef CONFIG_DRM_CLIENT_SPLASH
+void drm_splash_register(struct drm_device *dev,
+                        const struct drm_format_info *format);
+#else
+static inline void drm_splash_register(struct drm_device *dev,
+                                      const struct drm_format_info *format)
+{}
+#endif
+
  #endif
diff --git a/drivers/gpu/drm/clients/drm_client_setup.c 
b/drivers/gpu/drm/clients/drm_client_setup.c
index 
515aceac22b18161a14bd60be4acedc1ddd05bc5..c19498938ee3ba442f7502b27a9c33dfff45a203
 100644
--- a/drivers/gpu/drm/clients/drm_client_setup.c
+++ b/drivers/gpu/drm/clients/drm_client_setup.c
@@ -56,6 +56,14 @@ void drm_client_setup(struct drm_device *dev, const struct 
drm_format_info *form
                return;
        }
  #endif
+
+#ifdef CONFIG_DRM_CLIENT_SPLASH
+       if (!strcmp(drm_client_default, "splash")) {
+               drm_splash_register(dev, format);
+               return;
+       }
+#endif
+
        if (strcmp(drm_client_default, ""))
                drm_warn(dev, "Unknown DRM client %s\n", drm_client_default);
  }
diff --git a/drivers/gpu/drm/clients/drm_splash.c 
b/drivers/gpu/drm/clients/drm_splash.c
new file mode 100644
index 
0000000000000000000000000000000000000000..204a5256ef03b6edb81e5dc8c49b5929cb51ff92
--- /dev/null
+++ b/drivers/gpu/drm/clients/drm_splash.c
@@ -0,0 +1,883 @@
+// SPDX-License-Identifier: GPL-2.0 or MIT
+/*
+ * Copyright (c) 2025-2026 Francesco Valla <[email protected]>
+ *
+ */
+
+#include <linux/atomic.h>
+#include <linux/device.h>
+#include <linux/efi-bgrt.h>
+#include <linux/firmware.h>
+#include <linux/init.h>
+#include <linux/iosys-map.h>
+#include <linux/kthread.h>
+#include <linux/module.h>
+#include <linux/types.h>
+
+#include <drm/drm_client.h>
+#include <drm/drm_drv.h>
+#include <drm/drm_fourcc.h>
+#include <drm/drm_framebuffer.h>
+#include <drm/drm_plane.h>
+#include <drm/drm_print.h>
+
+#include "drm_client_internal.h"
+#include "drm_draw_internal.h"
+#include "drm_internal.h"
+
+/**
+ * DOC: overview
+ *
+ * This is a simple graphic bootsplash, able to display either a plain color or
+ * a static image.
+ */
+
+static unsigned int splash_color = CONFIG_DRM_CLIENT_SPLASH_BACKGROUND_COLOR;
+module_param(splash_color, uint, 0400);
+MODULE_PARM_DESC(splash_color, "Splash background color (RGB888)");

Does this really need to be a module parameter(s) in addition to the kconfig option(s)? Just wondering what the use case you envisioned is. In my mind I was thinking in an embedded system manufacturing flow maybe you would set it to red in the case of a hardware test failure on the line or something.

+
+#if IS_ENABLED(CONFIG_DRM_CLIENT_SPLASH_SRC_BMP)
+#define DEFAULT_SPLASH_BMP "drm_splash.bmp"
+static char *splash_bmp = DEFAULT_SPLASH_BMP;
+module_param(splash_bmp, charp, 0400);
+MODULE_PARM_DESC(splash_bmp, "Name of splash image (default: \"" DEFAULT_SPLASH_BMP 
"\")");
+#endif // CONFIG_DRM_CLIENT_SPLASH_SRC_BMP
+
+#if IS_ENABLED(CONFIG_DRM_CLIENT_SPLASH_BMP_SUPPORT)
+#define BMP_FILE_MAGIC_ID 0x4d42
+
+/* BMP header structures copied from drivers/video/fbdev/efifb.c */
+struct bmp_file_header {
+       u16 id;
+       u32 file_size;
+       u32 reserved;
+       u32 bitmap_offset;
+} __packed;
+
+struct bmp_dib_header {
+       u32 dib_header_size;
+       s32 width;
+       s32 height;
+       u16 planes;
+       u16 bpp;
+       u32 compression;
+       u32 bitmap_size;
+       u32 horz_resolution;
+       u32 vert_resolution;
+       u32 colors_used;
+       u32 colors_important;
+} __packed;
+#endif // CONFIG_DRM_CLIENT_SPLASH_BMP_SUPPORT
+
+typedef int (*drm_splash_data_get_func_t)(void *priv, const u8 **data, size_t 
*size);
+typedef void (*drm_splash_data_release_func_t)(void *priv);
+
+struct drm_splash_scanout {
+       int id;
+       u32 format;
+       unsigned int width;
+       unsigned int height;
+       struct drm_client_buffer *buffer;
+       bool bg_drawn;
+};
+
+struct drm_splash {
+       struct drm_client_dev client;
+       u32 preferred_format;
+       struct device dev;
+
+       struct task_struct *thread;
+       atomic_t pending;
+
+       struct mutex hotplug_lock;
+       bool initialized;
+
+       u32 n_scanout;
+       struct drm_splash_scanout *scanout;
+
+       spinlock_t data_lock;
+       drm_splash_data_get_func_t data_get;
+       drm_splash_data_release_func_t data_release;
+       void *data_priv;
+};
+
+static struct drm_splash *client_to_drm_splash(struct drm_client_dev *client)
+{
+       return container_of_const(client, struct drm_splash, client);
+}
+
+static void __maybe_unused
+drm_splash_data_source_push(struct drm_splash *splash,
+                           drm_splash_data_get_func_t get,
+                           drm_splash_data_release_func_t release,
+                           void *priv)
+{
+       guard(spinlock)(&splash->data_lock);
+
+       /* Release previous data */
+       if (splash->data_release)
+               splash->data_release(splash->data_priv);
+
+       splash->data_get = get;
+       splash->data_release = release;
+       splash->data_priv = priv;
+}
+
+static void drm_splash_data_source_pop(struct drm_splash *splash,
+                                      drm_splash_data_get_func_t *get,
+                                      drm_splash_data_release_func_t *release,
+                                      void **priv)
+{
+       guard(spinlock)(&splash->data_lock);
+
+       *get = splash->data_get;
+       splash->data_get = NULL;
+
+       *release = splash->data_release;
+       splash->data_release = NULL;
+
+       *priv = splash->data_priv;
+       splash->data_priv = NULL;
+}
+
+static struct drm_splash_scanout *
+get_scanout_from_tile_group(struct drm_splash *splash, int id)
+{
+       int j;
+
+       for (j = 0; j < splash->n_scanout; j++)
+               if (splash->scanout[j].id == id)
+                       return &splash->scanout[j];
+
+       return NULL;
+}
+
+static u32 drm_splash_find_usable_format(struct drm_plane *plane,
+                                        u32 preferred_format)
+{
+       int i;
+
+       /* Check if the preferred format can be used */
+       for (i = 0; i < plane->format_count; i++)
+               if (plane->format_types[i] == preferred_format)
+                       return preferred_format;
+
+       /* Otherwise, find the first format that can be converted from XRGB8888 
*/
+       for (i = 0; i < plane->format_count; i++)
+               if (drm_draw_color_from_xrgb8888(0xffffffff, 
plane->format_types[i]) != 0)
+                       return plane->format_types[i];
+
+       return DRM_FORMAT_INVALID;
+}
+
+static void drm_splash_fill(struct iosys_map *map, unsigned int dst_pitch,
+                           unsigned int height, unsigned int width,
+                           u32 px_width, u32 color)
+{
+       switch (px_width) {
+       case 2:
+               drm_draw_fill16(map, dst_pitch, height, width, color);
+               break;
+       case 3:
+               drm_draw_fill24(map, dst_pitch, height, width, color);
+               break;
+       case 4:
+               drm_draw_fill32(map, dst_pitch, height, width, color);
+               break;
+       default:
+               WARN_ONCE(1, "Can't fill with pixel width %d", px_width);
+       }
+}
+
+static int drm_splash_fill_solid_color(struct drm_client_buffer *buffer, u32 
color)
+{
+       struct drm_client_dev *client = buffer->client;
+       struct drm_framebuffer *fb = buffer->fb;
+       struct drm_rect r = DRM_RECT_INIT(0, 0, fb->width, fb->height);
+       u32 px_width = fb->format->cpp[0];
+       struct iosys_map map;
+       int ret;
+
+       ret = drm_client_buffer_vmap_local(buffer, &map);
+       if (ret) {
+               drm_err(client->dev, "splash: cannot vmap buffer: %d", ret);
+               return ret;
+       }
+
+       drm_splash_fill(&map, fb->pitches[0], drm_rect_height(&r),
+                       drm_rect_width(&r), px_width, color);
+
+       drm_client_buffer_vunmap_local(buffer);
+
+       return drm_client_buffer_flush(buffer, &r);
+}
+
+#if IS_ENABLED(CONFIG_DRM_CLIENT_SPLASH_BMP_SUPPORT)
+static void drm_splash_blit_pix16(struct iosys_map *map, unsigned int dpitch,
+                                 unsigned int x_pad, unsigned int y_pad,
+                                 const u8 *sbuf8, unsigned int spitch,
+                                 unsigned int width, unsigned int height,
+                                 bool invert_y, u32 format)
+{
+       unsigned int x, y, src_offset, dst_offset;
+       u32 scolor, dcolor, wr_off;
+
+       for (y = 0; y < height; y++) {
+               src_offset = (invert_y ? (height - y - 1) : y) * spitch;
+               dst_offset = (y_pad + y) * dpitch;
+
+               for (x = 0; x < width; x++) {
+                       scolor = *(const u32 *)(&sbuf8[src_offset + 3 * x]);
+                       dcolor = drm_draw_color_from_xrgb8888(scolor, format);
+                       wr_off = dst_offset + (x_pad + x) * sizeof(u16);
+
+                       iosys_map_wr(map, wr_off, u16, dcolor);
+               }
+       }
+}
+
+static void drm_splash_blit_pix24(struct iosys_map *map, unsigned int dpitch,
+                                 unsigned int x_pad, unsigned int y_pad,
+                                 const u8 *sbuf8, unsigned int spitch,
+                                 unsigned int width, unsigned int height,
+                                 bool invert_y, u32 format)
+{
+       unsigned int x, y, src_offset, dst_offset;
+       u32 scolor, dcolor, wr_off;
+
+       for (y = 0; y < height; y++) {
+               src_offset = (invert_y ? (height - y - 1) : y) * spitch;
+               dst_offset = (y_pad + y) * dpitch;
+
+               for (x = 0; x < width; x++) {
+                       scolor = *(const u32 *)(&sbuf8[src_offset + 3 * x]);
+                       dcolor = drm_draw_color_from_xrgb8888(scolor, format);
+                       wr_off = dst_offset + (x_pad + x) * 3;
+
+                       iosys_map_wr(map, wr_off, u8, (dcolor & 0x000000FF) >> 
0);
+                       iosys_map_wr(map, wr_off + 1, u8, (dcolor & 0x0000FF00) 
>> 8);
+                       iosys_map_wr(map, wr_off + 2, u8, (dcolor & 0x00FF0000) 
>> 16);
+               }
+       }
+}
+
+static void drm_splash_blit_pix32(struct iosys_map *map, unsigned int dpitch,
+                                 unsigned int x_pad, unsigned int y_pad,
+                                 const u8 *sbuf8, unsigned int spitch,
+                                 unsigned int width, unsigned int height,
+                                 bool invert_y, u32 format)
+{
+       unsigned int x, y, src_offset, dst_offset;
+       u32 scolor, dcolor, wr_off;
+
+       for (y = 0; y < height; y++) {
+               src_offset = (invert_y ? (height - y - 1) : y) * spitch;
+               dst_offset = (y_pad + y) * dpitch;
+
+               for (x = 0; x < width; x++) {
+                       scolor = *(const u32 *)(&sbuf8[src_offset + 3 * x]);
+                       dcolor = drm_draw_color_from_xrgb8888(scolor, format);
+                       wr_off = dst_offset + (x_pad + x) * sizeof(u32);
+
+                       iosys_map_wr(map, wr_off, u32, dcolor);
+               }
+       }
+}
+
+static void drm_splash_blit_rgb888(struct iosys_map *map, unsigned int dpitch,
+                                  unsigned int x_pad, unsigned int y_pad,
+                                  const u8 *sbuf8, unsigned int spitch,
+                                  unsigned int width, unsigned int height,
+                                  bool invert_y)
+{
+       unsigned int y, src_offset, dst_offset;
+
+       for (y = 0; y < height; y++) {
+               src_offset = (invert_y ? (height - y - 1) : y) * spitch;
+               dst_offset = (y_pad + y) * dpitch + x_pad * 3;
+
+               iosys_map_memcpy_to(map, dst_offset, &sbuf8[src_offset], width 
* 3);
+       }
+}
+
+static int drm_splash_bmp_to_scanout(struct drm_splash_scanout *scanout,
+                                    const u8 *data, size_t data_len)
+
+{
+       struct drm_client_buffer *buffer = scanout->buffer;
+       struct drm_client_dev *client = buffer->client;
+       struct drm_framebuffer *fb = buffer->fb;
+       u32 px_width = fb->format->cpp[0];
+       const struct bmp_file_header *file_header;
+       const struct bmp_dib_header *dib_header;
+       u32 bmp_width, bmp_height, bmp_pitch;
+       bool bmp_invert_y;
+       unsigned int x_pad, y_pad;
+       const u8 *image_data;
+       struct iosys_map map;
+       struct drm_rect r;
+       int ret;
+
+       if (data_len < (sizeof(*file_header) + sizeof(*dib_header))) {
+               drm_err(client->dev, "splash: BMP file too short");
+               return -EINVAL;
+       }
+
+       file_header = (const struct bmp_file_header *)data;
+       if (file_header->id != BMP_FILE_MAGIC_ID) {
+               drm_err(client->dev, "splash: invalid BMP magic 0x%04X",
+                       file_header->id);
+               return -EINVAL;
+       }
+
+       dib_header = (const struct bmp_dib_header *)(data + 
sizeof(*file_header));
+
+       /* Restrict supported format to uncompressed, 24bit RGB888 */
+       if (dib_header->dib_header_size != 40 || dib_header->width < 0 ||
+           dib_header->planes != 1 || dib_header->compression != 0 ||
+           dib_header->bpp != 24) {
+               drm_err(client->dev, "splash: invalid BMP format");
+               return -EINVAL;
+       }
+
+       bmp_width = dib_header->width;
+       bmp_height = abs(dib_header->height);
+       bmp_pitch = round_up(3 * bmp_width, 4);
+       bmp_invert_y = (dib_header->height > 0);
+
+       if ((file_header->bitmap_offset + bmp_pitch * bmp_height) > data_len) {
+               drm_err(client->dev, "splash: invalid BMP size");
+               return -EINVAL;
+       }
+
+       if (bmp_width > scanout->width || bmp_height > scanout->height) {
+               drm_err(client->dev, "splash: BMP image is too big for the 
screen");
+               return -EINVAL;
+       }
+
+       image_data = data + file_header->bitmap_offset;
+
+       ret = drm_client_buffer_vmap_local(buffer, &map);
+       if (ret) {
+               drm_err(client->dev, "splash: cannot vmap buffer: %d", ret);
+               return ret;
+       }
+
+       /* Center X and Y */
+       x_pad = (scanout->width - bmp_width) / 2;
+       y_pad = (scanout->height - bmp_height) / 2;
+       r = DRM_RECT_INIT(x_pad, y_pad, bmp_width, bmp_height);
+
+       /* In case the target format is RGB888, source data can be copied to
+        * the video buffer line by line, avoiding some overhead.
+        */
+       if (scanout->format == DRM_FORMAT_RGB888) {
+               drm_splash_blit_rgb888(&map, fb->pitches[0], x_pad, y_pad,
+                                      image_data, bmp_pitch, bmp_width,
+                                      bmp_height, bmp_invert_y);
+       } else {
+               switch (px_width) {
+               case 2:
+                       drm_splash_blit_pix16(&map, fb->pitches[0], x_pad,
+                                             y_pad, image_data, bmp_pitch,
+                                             bmp_width, bmp_height,
+                                             bmp_invert_y, scanout->format);
+                       break;
+               case 3:
+                       drm_splash_blit_pix24(&map, fb->pitches[0], x_pad,
+                                             y_pad, image_data, bmp_pitch,
+                                             bmp_width, bmp_height,
+                                             bmp_invert_y, scanout->format);
+                       break;
+               case 4:
+                       drm_splash_blit_pix32(&map, fb->pitches[0], x_pad,
+                                             y_pad, image_data, bmp_pitch,
+                                             bmp_width, bmp_height,
+                                             bmp_invert_y, scanout->format);
+                       break;
+               default:
+                       drm_warn_once(client->dev,
+                                     "splash: can't blit with pixel width %d",
+                                     px_width);
+               }
+       }
+
+       drm_client_buffer_vunmap_local(buffer);
+
+       return drm_client_buffer_flush(buffer, &r);
+}
+#else
+static inline int drm_splash_bmp_to_scanout(struct drm_splash_scanout *scanout,
+                                           const u8 *data, size_t data_len)
+{
+       return -EOPNOTSUPP;
+}
+#endif
+
+static int drm_splash_draw_scanout(struct drm_splash *splash,
+                                  struct drm_splash_scanout *scanout,
+                                  const u8 *data, size_t data_len)
+{
+       if (!scanout->buffer)
+               return -ENODEV;
+
+       if (!scanout->bg_drawn) {
+               u32 color = drm_draw_color_from_xrgb8888(splash_color,
+                                                        scanout->format);
+               drm_splash_fill_solid_color(scanout->buffer, color);
+               scanout->bg_drawn = true;
+       }
+
+       if (data != NULL) {
+               /* Ignore the return value, since the solid color has already
+                * been drawn to screen.
+                */
+               drm_splash_bmp_to_scanout(scanout, data, data_len);
+       }
+
+       return 0;
+}
+
+static int drm_splash_render_thread(void *data)
+{
+       struct drm_splash *splash = data;
+       struct drm_client_dev *client = &splash->client;
+
+       while (!kthread_should_stop()) {
+               unsigned int draw_count = 0;
+               drm_splash_data_get_func_t get_fn = NULL;
+               drm_splash_data_release_func_t release_fn = NULL;
+               void *priv = NULL;
+               const u8 *img_data = NULL;
+               size_t img_data_len = 0;
+               int i, ret;
+
+               drm_splash_data_source_pop(splash, &get_fn, &release_fn, &priv);
+
+               if (get_fn) {
+                       ret = get_fn(priv, &img_data, &img_data_len);
+                       if (ret) {
+                               drm_err(client->dev,
+                                       "splash: failed to get image data: %d",
+                                       ret);
+                       }
+               }
+
+               for (i = 0; i < splash->n_scanout; i++) {
+                       ret = drm_splash_draw_scanout(splash,
+                                                     &splash->scanout[i],
+                                                     img_data, img_data_len);
+                       if (ret) {
+                               drm_err(client->dev,
+                                       "splash: failed to fill scanout %d: %d",
+                                       i, ret);
+                               continue;
+                       }
+
+                       draw_count++;
+               }
+
+               if (release_fn)
+                       release_fn(priv);
+
+               if (draw_count > 0) {
+                       ret = drm_client_modeset_commit(client);
+                       /* If commit returns EBUSY, another master showed up.
+                        * This means that the splash is no more required.
+                        */
+                       if (ret == -EBUSY) {
+                               drm_info(client->dev,
+                                       "splash: not master anymore, exiting");
+                               break;
+                       }
+               }
+
+               /* If no changes arrived in the mean time, wait to be awaken,
+                * e.g.by a firmware callback.
+                */
+               if (atomic_xchg(&splash->pending, 0) == 0)
+                       set_current_state(TASK_UNINTERRUPTIBLE);
+
+               schedule();
+       }
+
+       return 0;
+}
+
+static inline void drm_splash_wake_render_thread(struct drm_splash *splash)
+{
+       atomic_set(&splash->pending, 1);
+       wake_up_process(splash->thread);
+}
+
+#if IS_ENABLED(CONFIG_DRM_CLIENT_SPLASH_SRC_BMP)
+static int drm_splash_fw_get(void *priv, const u8 **data, size_t *size)
+{
+       const struct firmware *fw = priv;
+
+       if (!fw)
+               return -ENODATA;
+
+       *data = fw->data;
+       *size = fw->size;
+
+       return 0;
+}
+
+static void drm_splash_fw_release(void *priv)
+{
+       const struct firmware *fw = priv;
+
+       if (fw)
+               release_firmware(fw);
+}
+
+static void drm_splash_fw_callback(const struct firmware *fw, void *context)
+{
+       struct drm_splash *splash = context;
+       struct drm_client_dev *client = &splash->client;
+
+       if (!fw || !fw->data) {
+               drm_err(client->dev, "splash: no firmware");
+               return;
+       }
+
+       drm_splash_data_source_push(splash, drm_splash_fw_get,
+                                   drm_splash_fw_release, (void *)fw);
+
+       /* Wake the render thread */
+       drm_dbg(client->dev, "splash: firmware loaded, wake up drawing thread");
+       drm_splash_wake_render_thread(splash);
+}
+
+static int drm_splash_fw_request_bmp(struct drm_splash *splash)
+{
+       struct drm_client_dev *client = &splash->client;
+
+       drm_info(client->dev, "splash: request %s as firmware", splash_bmp);
+
+       return request_firmware_nowait(THIS_MODULE, FW_ACTION_UEVENT,
+                                      splash_bmp, client->dev->dev, GFP_KERNEL,
+                                      splash, drm_splash_fw_callback);
+}
+#else
+static inline int drm_splash_fw_request_bmp(struct drm_splash *splash)
+{
+       return -EOPNOTSUPP;
+}
+#endif // CONFIG_DRM_CLIENT_SPLASH_SRC_BMP
+
+#if IS_ENABLED(CONFIG_DRM_CLIENT_SPLASH_SRC_BGRT)
+static int drm_splash_bgrt_get_data(void *priv, const u8 **data, size_t *size)
+{
+       void *bgrt_image = priv;
+
+       *data = bgrt_image;
+       *size = bgrt_image_size;
+
+       return 0;
+}
+
+static void drm_splash_bgrt_release(void *priv)
+{
+       void *bgrt_image = priv;
+
+       if (bgrt_image)
+               memunmap(bgrt_image);
+}
+
+static int drm_splash_bgrt_load(struct drm_splash *splash)
+{
+       struct drm_client_dev *client = &splash->client;
+       void *bgrt_image = NULL;
+
+       drm_info(client->dev, "splash: using EFI BGRT");
+
+       if (!bgrt_tab.image_address) {
+               drm_info(client->dev, "splash: no BGRT found");
+               return -ENOENT;
+       }
+
+       if (bgrt_tab.status & 0x06) {
+               drm_info(client->dev, "splash: BGRT rotation bits set, 
skipping");
+               return -EOPNOTSUPP;
+       }
+
+       drm_dbg(client->dev, "splash: BGRT image is at 0x%016llx, size=%zX",
+               bgrt_tab.image_address, bgrt_image_size);
+
+       bgrt_image = memremap(bgrt_tab.image_address, bgrt_image_size,
+                             MEMREMAP_WB);
+       if (!bgrt_image) {
+               drm_warn(client->dev, "splash: failed to map BGRT image 
memory");
+               return -ENOMEM;
+       }
+
+       drm_splash_data_source_push(splash, drm_splash_bgrt_get_data,
+                                   drm_splash_bgrt_release, bgrt_image);
+
+       drm_splash_wake_render_thread(splash);
+
+       return 0;
+}
+#else
+static inline int drm_splash_bgrt_load(struct drm_splash *splash)
+{
+       return -EOPNOTSUPP;
+}
+#endif // CONFIG_DRM_CLIENT_SPLASH_SRC_BGRT
+
+static int drm_splash_init_client(struct drm_splash *splash)
+{
+       struct drm_client_dev *client = &splash->client;
+       struct drm_mode_set *modeset;
+       unsigned int modeset_mask = 0;
+       unsigned int fb_count = 0;
+       int j;
+
+       if (drm_client_modeset_probe(client, 0, 0))
+               return -1;
+
+       j = 0;
+       drm_client_for_each_modeset(modeset, client) {
+               struct drm_splash_scanout *tmp;
+               struct drm_splash_scanout *scanout;
+               u32 format;
+               int id = -1;
+
+               /* Skip modesets without a mode */
+               if (!modeset->mode)
+                       continue;
+
+               if (modeset->connectors[0]->has_tile) {
+                       struct drm_splash_scanout *tiled;
+                       int new_id = modeset->connectors[0]->tile_group->id;
+
+                       /* Tiled modesets contribute to a single framebuffer,
+                        * check if this tiled group has already been seen.
+                        */
+                       tiled = get_scanout_from_tile_group(splash, new_id);
+                       if (tiled != NULL) {
+                               if (!modeset->x)
+                                       tiled->width += modeset->mode->vdisplay;
+                               if (!modeset->y)
+                                       tiled->height += 
modeset->mode->hdisplay;
+                               modeset->fb = tiled->buffer->fb;
+                               continue;
+                       }
+
+                       /* New tile group, save its ID for later */
+                       id = new_id;
+               }
+
+               format = drm_splash_find_usable_format(modeset->crtc->primary,
+                                                      
splash->preferred_format);
+               if (format == DRM_FORMAT_INVALID) {
+                       drm_warn(client->dev,
+                                "splash: can't find a usable format for 
modeset");
+                       continue;
+               }
+
+               tmp = krealloc(splash->scanout,
+                              (splash->n_scanout + 1) * 
sizeof(*splash->scanout),
+                              GFP_KERNEL);
+               if (!tmp) {
+                       drm_warn(client->dev,
+                                "splash: can't reallocate the scanout array");
+                       break;
+               }
+
+               splash->scanout = tmp;
+               scanout = &splash->scanout[splash->n_scanout];
+               splash->n_scanout++;
+
+               memset(scanout, 0, sizeof(*scanout));
+               scanout->id = id;
+               scanout->format = format;
+               scanout->width = modeset->mode->hdisplay;
+               scanout->height = modeset->mode->vdisplay;
+
+               modeset_mask |= BIT(j);
+               j++;
+       }
+
+       /* Now that all sensible modesets have been collected, allocate buffers 
*/
+       j = 0;
+       drm_client_for_each_modeset(modeset, client) {
+               struct drm_splash_scanout *scanout;
+
+               if (!(modeset_mask & BIT(j)))
+                       continue;
+
+               scanout = &splash->scanout[j];
+               j++;
+
+               scanout->buffer = drm_client_buffer_create_dumb(client,
+                                                               scanout->width,
+                                                               scanout->height,
+                                                               
scanout->format);
+               if (IS_ERR(scanout->buffer)) {
+                       drm_warn(client->dev,
+                                "splash: can't create dumb buffer %d %d %p4cc",
+                                scanout->width, scanout->height, 
&scanout->format);
+                       continue;
+               }
+
+               drm_info(client->dev, "splash: created dumb buffer %d %d %p4cc",
+                        scanout->width, scanout->height, &scanout->format);
+
+               modeset->fb = scanout->buffer->fb;
+               fb_count++;
+       }
+
+       return (fb_count == 0) ? -ENODEV : 0;
+}
+
+static void drm_splash_free_scanout(struct drm_client_dev *client)
+{
+       struct drm_splash *splash = client_to_drm_splash(client);
+       int i;
+
+       if (splash->n_scanout) {
+               for (i = 0; i < splash->n_scanout; i++)
+                       drm_client_buffer_delete(splash->scanout[i].buffer);
+
+               splash->n_scanout = 0;
+               kfree(splash->scanout);
+               splash->scanout = NULL;
+       }
+}
+
+static int drm_splash_client_hotplug(struct drm_client_dev *client)
+{
+       struct drm_splash *splash = client_to_drm_splash(client);
+       int ret;
+
+       guard(mutex)(&splash->hotplug_lock);
+
+       /* The modesets that get a splash are defined at first hotplug event */
+       if (splash->initialized)
+               return 0;
+
+       ret = drm_splash_init_client(splash);
+       if (ret == -ENODEV) {
+               drm_info(client->dev, "splash: no modeset found");
+               return 0;
+       } else if (ret) {
+               drm_err(client->dev,
+                       "splash: failed to init client: %d", ret);
+               return ret;
+       }
+
+       /* Create the render thread, waken later */
+       splash->thread = kthread_create(drm_splash_render_thread,
+                                       splash, "drm_splash_%s",
+                                       client->dev->unique);
+       if (IS_ERR(splash->thread)) {
+               ret = PTR_ERR(splash->thread);
+               drm_err(client->dev, "splash: failed to create render thread: 
%d", ret);
+               drm_splash_free_scanout(client);
+               return ret;
+       }
+
+       if (IS_ENABLED(CONFIG_DRM_CLIENT_SPLASH_SRC_BMP))
+               ret = drm_splash_fw_request_bmp(splash);
+       else if (IS_ENABLED(CONFIG_DRM_CLIENT_SPLASH_SRC_BGRT))
+               ret = drm_splash_bgrt_load(splash);

I'm not sure this logic will actually work in this order.
CONFIG_DRM_CLIENT_SPLASH_SRC_BGRT selects
CONFIG_DRM_CLIENT_SPLASH_SRC_BMP

So won't the BGRT path never run?

+       else
+               ret = 0;
+
+       if (ret) {
+               drm_err(client->dev, "splash: failed to kick image load: %d", 
ret);
+               kthread_stop(splash->thread);
+               drm_splash_free_scanout(client);
+               return ret;
+       }
+
+       /* Wake the render thread to show initial contents */
+       drm_splash_wake_render_thread(splash);
+
+       splash->initialized = true;
+
+       return 0;
+}
+
+static int drm_splash_client_restore(struct drm_client_dev *client, bool force)
+{
+       int ret;
+
+       if (force)
+               ret = drm_client_modeset_commit_locked(client);
+       else
+               ret = drm_client_modeset_commit(client);
+
+       return ret;
+}
+
+static void drm_splash_client_unregister(struct drm_client_dev *client)
+{
+       struct drm_splash *splash = client_to_drm_splash(client);
+
+       kthread_stop(splash->thread);
+       drm_splash_free_scanout(client);
+       drm_client_release(client);
+
+       if (splash->data_release)
+               splash->data_release(splash->data_priv);
+}
+
+static void drm_splash_client_free(struct drm_client_dev *client)
+{
+       struct drm_splash *splash = client_to_drm_splash(client);
+       struct drm_device *dev = client->dev;
+
+       mutex_destroy(&splash->hotplug_lock);
+       kfree(splash);
+
+       drm_dbg(dev, "Unregistered with drm splash");
+}
+
+static const struct drm_client_funcs drm_splash_client_funcs = {
+       .owner          = THIS_MODULE,
+       .hotplug        = drm_splash_client_hotplug,
+       .restore        = drm_splash_client_restore,
+       .unregister     = drm_splash_client_unregister,
+       .free           = drm_splash_client_free,
+};
+
+/**
+ * drm_splash_register() - Register a drm device to drm_splash
+ * @dev: the drm device to register.
+ * @format: drm device preferred format.
+ */
+void drm_splash_register(struct drm_device *dev,
+                        const struct drm_format_info *format)
+{
+       struct drm_splash *splash;
+
+       splash = kzalloc(sizeof(*splash), GFP_KERNEL);
+       if (!splash)
+               goto err_warn;
+
+       mutex_init(&splash->hotplug_lock);
+       spin_lock_init(&splash->data_lock);
+
+       if (format && format->num_planes == 1)
+               splash->preferred_format = format->format;
+       else
+               splash->preferred_format = DRM_FORMAT_RGB888;
+
+       if (drm_client_init(dev, &splash->client, "drm_splash",
+                           &drm_splash_client_funcs))
+               goto err_free;
+
+       drm_client_register(&splash->client);
+       drm_dbg(dev, "Registered with drm splash");
+
+       return;
+
+err_free:
+       kfree(splash);
+err_warn:
+       drm_warn(dev, "Failed to register with drm splash");
+}



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