Re: [PATCH RFC v4 03/13] drm: client: add splash client

[Jani Nikula]

On Thu, 01 Oct 2026, Màxim Pedraza Padilla <maximpedraza@xxxxxxxxx> wrote:
> From: Francesco Valla <francesco@xxxxxxxx>
>
> Add a DRM client that draws a simple splash, with possibility to show:
>
>   - the logo provided by EFI BGRT;
>   - a static BMP image (loaded as firmware);
>   - a colored background.
>
> 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).
>
> 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 <francesco@xxxxxxxx>
> [Màxim: fix the render thread never exiting when the BMP firmware is
>  missing, a lost wake-up, and stopping a thread that had exited, never
>  existed or failed to start; fix buffers going to the wrong modesets
>  and tiled groups in drm_splash_init_client(), and take modeset_mutex
>  there; don't keep an ERR_PTR as a buffer; unmap the image only once;
>  fix use-after-frees on unbind and in the firmware callback; check the
>  BMP size without overflowing; indent the Kconfig entry with tabs]
> Signed-off-by: Màxim Pedraza Padilla <maximpedraza@xxxxxxxxx>
> ---
>  drivers/gpu/drm/clients/Kconfig               |   63 +-
>  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          | 1028 +++++++++++++++++
>  5 files changed, 1108 insertions(+), 1 deletion(-)
>  create mode 100644 drivers/gpu/drm/clients/drm_splash.c
>
> diff --git a/drivers/gpu/drm/clients/Kconfig b/drivers/gpu/drm/clients/Kconfig
> index 8d8bc37ec9f2..cbe271c3a23f 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 +86,63 @@ 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_SRC_BGRT
> +	bool "EFI BGRT as splash source"
> +	depends on DRM_CLIENT_SPLASH
> +	depends on ACPI_BGRT
> +	select DRM_CLIENT_SPLASH_BMP_SUPPORT
> +	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.
> +
> +config DRM_CLIENT_SPLASH_SRC_BMP
> +	bool "BMP image as splash source"
> +	depends on DRM_CLIENT_SPLASH
> +	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_BMP_SUPPORT
> +	bool
> +
>  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 +165,12 @@ 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 +178,7 @@ 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
>  	default ""
>  
>  endmenu
> diff --git a/drivers/gpu/drm/clients/Makefile b/drivers/gpu/drm/clients/Makefile
> index 1304ff358509..b43b1e86fe8e 100644
> --- a/drivers/gpu/drm/clients/Makefile
> +++ b/drivers/gpu/drm/clients/Makefile
> @@ -6,4 +6,5 @@ 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_fbdev_helper.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 6dc078bf6503..48ee0c1c2529 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 515aceac22b1..c19498938ee3 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 000000000000..66c192139d9c
> --- /dev/null
> +++ b/drivers/gpu/drm/clients/drm_splash.c
> @@ -0,0 +1,1028 @@
> +// SPDX-License-Identifier: GPL-2.0 or MIT
> +/*
> + * Copyright (c) 2025-2026 Francesco Valla <francesco@xxxxxxxx>
> + */
> +
> +#include <linux/atomic.h>
> +#include <linux/completion.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/overflow.h>
> +#include <linux/types.h>
> +#include <linux/unaligned.h>
> +
> +#include <acpi/actbl1.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)");
> +
> +#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
> +
> +#define BMP_FILE_MAGIC_ID 0x4d42
> +
> +/* BMP header structures copied from drivers/video/fbdev/efifb.c */
> +struct bmp_file_header {
> +	__le16 id;
> +	__le32 file_size;
> +	__le32 reserved;
> +	__le32 bitmap_offset;
> +} __packed;
> +
> +struct bmp_dib_header {
> +	__le32 dib_header_size;
> +	__le32 width;
> +	__le32 height;
> +	__le16 planes;
> +	__le16 bpp;
> +	__le32 compression;
> +	__le32 bitmap_size;
> +	__le32 horz_resolution;
> +	__le32 vert_resolution;
> +	__le32 colors_used;
> +	__le32 colors_important;
> +} __packed;
> +
> +struct drm_splash_scanout {
> +	int id;
> +	/* Modesets scanning this buffer out, by position in the list */
> +	u32 modesets;
> +	u32 format;
> +	unsigned int width;
> +	unsigned int height;
> +	struct drm_client_buffer *buffer;
> +	bool bg_drawn;
> +	bool img_drawn;
> +};
> +
> +struct drm_splash {
> +	struct drm_client_dev client;
> +	u32 preferred_format;
> +	struct device dev;
> +
> +	struct task_struct *thread;
> +	atomic_t pending;
> +	/* A firmware request is in flight, so an image may still arrive */
> +	bool fw_pending;
> +	/* A request was made, and fw_done tells when its callback is over */
> +	bool fw_requested;
> +	struct completion fw_done;
> +
> +	/* Serialises hotplug events: the first one sets the modesets up */
> +	struct mutex hotplug_lock;
> +	bool initialized;
> +
> +	u32 n_scanout;
> +	struct drm_splash_scanout *scanout;
> +
> +	/* Hands fw over from the firmware callback to the render thread */
> +	spinlock_t fw_lock;
> +	const struct firmware *fw;
> +	void *map_data;
> +
> +	bool use_bgrt;
> +};
> +
> +static struct drm_splash *client_to_drm_splash(struct drm_client_dev *client)
> +{
> +	return container_of_const(client, struct drm_splash, client);
> +}
> +
> +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 inline void drm_splash_wake_render_thread(struct drm_splash *splash)
> +{
> +	wake_up_process(splash->thread);
> +}
> +
> +#if IS_ENABLED(CONFIG_DRM_CLIENT_SPLASH_SRC_BMP)
> +static int drm_splash_fw_load(struct drm_splash *splash, const u8 **data,
> +			      size_t *size)
> +{
> +	const struct firmware *fw;
> +
> +	scoped_guard(spinlock, &splash->fw_lock)
> +		fw = splash->fw;
> +
> +	if (!fw)
> +		return -ENOENT;
> +
> +	*data = fw->data;
> +	*size = fw->size;
> +
> +	return 0;
> +}
> +
> +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");
> +		release_firmware(fw);
> +		fw = NULL;
> +	}
> +
> +	scoped_guard(spinlock, &splash->fw_lock)
> +		splash->fw = fw;
> +
> +	/*
> +	 * Whether it came or not, nothing else is coming: the thread must be
> +	 * told either way, or it waits for good. Release, so that a thread
> +	 * that sees the flag clear also sees the firmware stored above.
> +	 */
> +	smp_store_release(&splash->fw_pending, false);
> +
> +	/* Wake the render thread */
> +	drm_dbg(client->dev, "splash: firmware request done, wake up drawing thread");
> +	atomic_set(&splash->pending, 1);
> +	drm_splash_wake_render_thread(splash);
> +
> +	/* Last: once this is seen, unregister may free the splash */
> +	complete(&splash->fw_done);
> +}
> +
> +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_load(struct drm_splash *splash, const u8 **data,
> +				     size_t *size)
> +{
> +	return -EOPNOTSUPP;
> +}
> +
> +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 bool drm_splash_bgrt_available(struct drm_splash *splash)
> +{
> +	struct drm_client_dev *client = &splash->client;
> +
> +	if (!bgrt_tab.image_address) {
> +		drm_info(client->dev, "splash: no BGRT found");
> +		return false;
> +	}
> +
> +	if (bgrt_tab.status & ACPI_BGRT_ORIENTATION_OFFSET) {
> +		drm_info(client->dev, "splash: BGRT rotation bits set, skipping");
> +		return false;
> +	}
> +
> +	return true;
> +}
> +
> +static inline unsigned int drm_splash_bgrt_get_xoffset(void)
> +{
> +	return bgrt_tab.image_offset_x;
> +}
> +
> +static inline unsigned int drm_splash_bgrt_get_yoffset(void)
> +{
> +	return bgrt_tab.image_offset_y;
> +}

I think helpers like these should be proper exported functions in
efi-bgrt.c with stubs in efi-bgrt.h for CONFIG_ACPI_BGRT=n. The
functions are not specific to drm splash, they're specific to efi-bgrt.

Basically don't expose bgrt_tab nor any of its fields or
bgrt_image_size, expose functions for each of them, and I think it'll
make the whole implementation better.

Side note, please don't use "static inline" in .c. Just let the compiler
do its job regarding inlining.


BR,
Jani.


> +
> +static int drm_splash_bgrt_load(struct drm_splash *splash, const u8 **data,
> +				size_t *size)
> +{
> +	struct drm_client_dev *client = &splash->client;
> +
> +	if (!drm_splash_bgrt_available(splash))
> +		return -ENOENT;
> +
> +	drm_dbg(client->dev, "splash: BGRT image is at 0x%016llx, size=%zX",
> +		bgrt_tab.image_address, bgrt_image_size);
> +
> +	splash->map_data = memremap(bgrt_tab.image_address, bgrt_image_size,
> +				    MEMREMAP_WB);
> +	if (!splash->map_data) {
> +		drm_warn(client->dev, "splash: failed to map BGRT image memory");
> +		return -ENOMEM;
> +	}
> +
> +	*data = splash->map_data;
> +	*size = bgrt_image_size;
> +
> +	return 0;
> +}
> +#else
> +static inline bool drm_splash_bgrt_available(struct drm_splash *splash)
> +{
> +	return false;
> +}
> +
> +static inline unsigned int drm_splash_bgrt_get_xoffset(void)
> +{
> +	return 0;
> +}
> +
> +static inline unsigned int drm_splash_bgrt_get_yoffset(void)
> +{
> +	return 0;
> +}
> +
> +static inline int drm_splash_bgrt_load(struct drm_splash *splash,
> +				       const u8 **data, size_t *size)
> +{
> +	return -EOPNOTSUPP;
> +}
> +#endif // CONFIG_DRM_CLIENT_SPLASH_SRC_BGRT
> +
> +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_can_convert_from_xrgb8888(plane->format_types[i]))
> +			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 *splash,
> +				     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 dib_header_size;
> +	u16 bmp_id, bmp_bpp, bmp_planes;
> +	u32 bmp_compression, bmp_pitch;
> +	s32 bmp_width, bmp_height;
> +	bool bmp_invert_y;
> +	u32 bitmap_offset;
> +	size_t row_len, pixels_len, end;
> +	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;
> +
> +	bmp_id = get_unaligned_le16(&file_header->id);
> +	if (bmp_id != BMP_FILE_MAGIC_ID) {
> +		drm_err(client->dev, "splash: invalid BMP magic 0x%04X", bmp_id);
> +		return -EINVAL;
> +	}
> +
> +	bitmap_offset = get_unaligned_le32(&file_header->bitmap_offset);
> +
> +	dib_header = (const struct bmp_dib_header *)(data + sizeof(*file_header));
> +
> +	dib_header_size = get_unaligned_le32(&dib_header->dib_header_size);
> +
> +	bmp_width = (s32)get_unaligned_le32(&dib_header->width);
> +	bmp_height = (s32)get_unaligned_le32(&dib_header->height);
> +	bmp_planes = get_unaligned_le16(&dib_header->planes);
> +	bmp_bpp = get_unaligned_le16(&dib_header->bpp);
> +	bmp_compression = get_unaligned_le32(&dib_header->compression);
> +
> +	/* Restrict supported format to uncompressed, 24bit RGB888 */
> +	if (dib_header_size != 40 || bmp_width <= 0 || bmp_height == 0 ||
> +	    bmp_height == S32_MIN || bmp_planes != 1 ||
> +	    bmp_compression != 0 || bmp_bpp != 24) {
> +		drm_err(client->dev, "splash: invalid BMP format");
> +		return -EINVAL;
> +	}
> +
> +	/* A positive height means bottom-to-top scan direction */
> +	bmp_invert_y = (bmp_height > 0);
> +	bmp_height = abs(bmp_height);
> +
> +	/*
> +	 * Every field comes from the image, which the firmware or the device
> +	 * tree supplied, so check the arithmetic before trusting the result:
> +	 * rows are padded to four bytes, and the pixels must end within the
> +	 * data.
> +	 */
> +	if (check_mul_overflow((size_t)bmp_width, (size_t)3, &row_len) ||
> +	    check_add_overflow(row_len, (size_t)3, &row_len) ||
> +	    check_mul_overflow(row_len & ~(size_t)3, (size_t)bmp_height,
> +			       &pixels_len) ||
> +	    check_add_overflow((size_t)bitmap_offset, pixels_len, &end) ||
> +	    end > data_len) {
> +		drm_err(client->dev, "splash: invalid BMP size");
> +		return -EINVAL;
> +	}
> +	bmp_pitch = row_len & ~(size_t)3;
> +
> +	if (bmp_width > scanout->width || bmp_height > scanout->height) {
> +		drm_err(client->dev, "splash: BMP image is too big for the screen");
> +		return -EINVAL;
> +	}
> +
> +	if (splash->use_bgrt) {
> +		x_pad = drm_splash_bgrt_get_xoffset();
> +		y_pad = drm_splash_bgrt_get_yoffset();
> +
> +		if ((x_pad + bmp_width) > scanout->width ||
> +		    (y_pad + bmp_height) > scanout->height) {
> +			drm_err(client->dev, "splash: BGRT image would overflow");
> +			return -EINVAL;
> +		}
> +
> +#ifdef CONFIG_X86
> +		/*
> +		 * BGRT sanity check, taken from efifb.c:
> +		 *
> +		 * On x86 some firmwares use a low non native resolution for
> +		 * the display when they have shown some text messages. While
> +		 * keeping the bgrt filled with info for the native resolution.
> +		 * If the bgrt image intended for the native resolution still
> +		 * fits, it will be displayed very close to the right edge of
> +		 * the display looking quite bad.
> +		 */
> +
> +		if (x_pad != (scanout->width - bmp_width) / 2) {
> +			drm_err(client->dev, "splash: BGRT sanity check failed");
> +			return -EINVAL;
> +		}
> +#endif
> +	} else {
> +		/* Center X and Y */
> +		x_pad = (scanout->width - bmp_width) / 2;
> +		y_pad = (scanout->height - bmp_height) / 2;
> +	}
> +
> +	image_data = data + bitmap_offset;
> +
> +	ret = drm_client_buffer_vmap_local(buffer, &map);
> +	if (ret) {
> +		drm_err(client->dev, "splash: cannot vmap buffer: %d", ret);
> +		return ret;
> +	}
> +
> +	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 *splash,
> +					    struct drm_splash_scanout *scanout,
> +					    const u8 *data, size_t data_len)
> +{
> +	return -EOPNOTSUPP;
> +}
> +#endif
> +
> +static int drm_splash_image_load(struct drm_splash *splash, const u8 **img_data,
> +				 size_t *img_data_len)
> +{
> +	int ret = 0;
> +
> +	if (splash->use_bgrt) {
> +		ret = drm_splash_bgrt_load(splash, img_data, img_data_len);
> +		if (ret)
> +			splash->use_bgrt = false;
> +	}
> +
> +	/* BGRT failed to load */
> +	if (!splash->use_bgrt)
> +		ret = drm_splash_fw_load(splash, img_data, img_data_len);
> +
> +	return ret;
> +}
> +
> +static void drm_splash_image_cleanup(struct drm_splash *splash)
> +{
> +	const struct firmware *fw = NULL;
> +
> +	/* Called after drawing and again at unregister: unmap only once */
> +	memunmap(splash->map_data);
> +	splash->map_data = NULL;
> +
> +	scoped_guard(spinlock, &splash->fw_lock) {
> +		fw = splash->fw;
> +		splash->fw = NULL;
> +	}
> +
> +	release_firmware(fw);
> +}
> +
> +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;
> +		const u8 *img_data = NULL;
> +		size_t img_data_len = 0;
> +		bool img_loaded, last;
> +		int i, ret;
> +
> +		drm_dbg(client->dev, "splash: run render thread...");
> +
> +		/*
> +		 * Whether this is the last pass has to be known before looking
> +		 * for the image: if the firmware lands while this pass runs,
> +		 * another pass has to pick it up.
> +		 */
> +		last = !smp_load_acquire(&splash->fw_pending);
> +
> +		ret = drm_splash_image_load(splash, &img_data, &img_data_len);
> +		img_loaded = (ret == 0);
> +
> +		for (i = 0; i < splash->n_scanout; i++) {
> +			struct drm_splash_scanout *scanout = &splash->scanout[i];
> +
> +			if (!scanout->buffer) {
> +				drm_err(client->dev,
> +					"splash: no buffer for scanout %d", i);
> +				continue;
> +			}
> +
> +			if (!scanout->bg_drawn) {
> +				drm_dbg(client->dev, "draw background for scanout %d", i);
> +				u32 color = drm_draw_color_from_xrgb8888(splash_color,
> +									 scanout->format);
> +				drm_splash_fill_solid_color(scanout->buffer, color);
> +				scanout->bg_drawn = true;
> +			}
> +
> +			if (img_loaded && !scanout->img_drawn) {
> +				drm_dbg(client->dev, "draw image for scanout %d", i);
> +				/* Ignore the return value, since the solid
> +				 * color has already been drawn to screen.
> +				 */
> +				ret = drm_splash_bmp_to_scanout(splash, scanout,
> +								img_data,
> +								img_data_len);
> +				scanout->img_drawn = (ret == 0);
> +			}
> +
> +			draw_count++;
> +		}
> +
> +		if (img_loaded)
> +			drm_splash_image_cleanup(splash);
> +
> +		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;
> +			}
> +		}
> +
> +		/* Done, or nothing could have arrived since the image was sought */
> +		if (img_loaded || last)
> +			break;
> +
> +		/*
> +		 * Wait for the firmware callback. The state is set before
> +		 * looking at the flag, so that a wake up in between is not
> +		 * lost, and the wait is idle rather than uninterruptible, as
> +		 * nothing guarantees how long it lasts.
> +		 */
> +		set_current_state(TASK_IDLE);
> +		if (atomic_xchg(&splash->pending, 0) || kthread_should_stop() ||
> +		    !READ_ONCE(splash->fw_pending)) {
> +			__set_current_state(TASK_RUNNING);
> +			continue;
> +		}
> +
> +		schedule();
> +	}
> +
> +	return 0;
> +}
> +
> +static int drm_splash_init_client(struct drm_splash *splash)
> +{
> +	struct drm_client_dev *client = &splash->client;
> +	struct drm_mode_set *modeset;
> +	unsigned int fb_count = 0;
> +	unsigned int i, k;
> +
> +	if (drm_client_modeset_probe(client, 0, 0))
> +		return -EIO;
> +
> +	mutex_lock(&client->modeset_mutex);
> +
> +	/*
> +	 * Collect one scanout per usable modeset, or per tile group. Each
> +	 * scanout records the modesets it feeds by their position in the
> +	 * list, so that the second pass below can find them again whatever
> +	 * was skipped in between.
> +	 */
> +	i = 0;
> +	drm_client_for_each_modeset(modeset, client) {
> +		struct drm_splash_scanout *tmp;
> +		struct drm_splash_scanout *scanout;
> +		unsigned int idx = i++;
> +		u32 format;
> +		int id = -1;
> +
> +		if (WARN_ON_ONCE(idx >= 32))
> +			break;
> +
> +		/* 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:
> +			 * the first column adds rows, the first row adds
> +			 * columns.
> +			 */
> +			tiled = get_scanout_from_tile_group(splash, new_id);
> +			if (tiled) {
> +				if (!modeset->x)
> +					tiled->height += modeset->mode->vdisplay;
> +				if (!modeset->y)
> +					tiled->width += modeset->mode->hdisplay;
> +				tiled->modesets |= BIT(idx);
> +				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->modesets = BIT(idx);
> +		scanout->format = format;
> +		scanout->width = modeset->mode->hdisplay;
> +		scanout->height = modeset->mode->vdisplay;
> +	}
> +
> +	/* Now that the sizes are known, allocate one buffer per scanout */
> +	for (k = 0; k < splash->n_scanout; k++) {
> +		struct drm_splash_scanout *scanout = &splash->scanout[k];
> +		struct drm_client_buffer *buffer;
> +
> +		buffer = drm_client_buffer_create_dumb(client, scanout->width,
> +						       scanout->height,
> +						       scanout->format);
> +		if (IS_ERR(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);
> +
> +		scanout->buffer = buffer;
> +		fb_count++;
> +	}
> +
> +	/* And point every modeset at the buffer of its scanout */
> +	i = 0;
> +	drm_client_for_each_modeset(modeset, client) {
> +		unsigned int idx = i++;
> +
> +		if (idx >= 32)
> +			break;
> +
> +		for (k = 0; k < splash->n_scanout; k++) {
> +			struct drm_splash_scanout *scanout = &splash->scanout[k];
> +
> +			if (scanout->buffer && (scanout->modesets & BIT(idx))) {
> +				modeset->fb = scanout->buffer->fb;
> +				break;
> +			}
> +		}
> +	}
> +
> +	mutex_unlock(&client->modeset_mutex);
> +
> +	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);
> +	struct task_struct *thread;
> +	int ret = 0;
> +
> +	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 */
> +	thread = kthread_create(drm_splash_render_thread, splash,
> +				"drm_splash_%s", client->dev->unique);
> +	if (IS_ERR(thread)) {
> +		ret = PTR_ERR(thread);
> +		drm_err(client->dev,
> +			"splash: failed to create render thread: %d", ret);
> +		drm_splash_free_scanout(client);
> +		return ret;
> +	}
> +
> +	/*
> +	 * The thread exits on its own once the splash is up, so hold on to
> +	 * it: kthread_stop() at unregister must not find it gone.
> +	 */
> +	get_task_struct(thread);
> +	splash->thread = thread;
> +
> +	splash->use_bgrt = drm_splash_bgrt_available(splash);
> +
> +	/* If no other image has been loaded, try to load a BMP as firmware */
> +	if (IS_ENABLED(CONFIG_DRM_CLIENT_SPLASH_SRC_BMP) && !splash->use_bgrt) {
> +		WRITE_ONCE(splash->fw_pending, true);
> +		ret = drm_splash_fw_request_bmp(splash);
> +		splash->fw_requested = !ret;
> +		if (ret) {
> +			drm_err(client->dev,
> +				"splash: failed to kick image load: %d", ret);
> +			kthread_stop_put(splash->thread);
> +			splash->thread = NULL;
> +			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);
> +
> +	/*
> +	 * A firmware request cannot be cancelled, and its callback uses the
> +	 * splash and wakes the thread: let it finish first. It is usually over
> +	 * already; at worst this waits for the firmware fallback timeout.
> +	 */
> +	if (splash->fw_requested)
> +		wait_for_completion(&splash->fw_done);
> +
> +	/* No thread if no output was usable at the first hotplug */
> +	if (splash->thread)
> +		kthread_stop_put(splash->thread);
> +	drm_splash_free_scanout(client);
> +	drm_splash_image_cleanup(splash);
> +
> +	/* Last: it ends up in drm_splash_client_free(), which frees splash */
> +	drm_client_release(client);
> +}
> +
> +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_obj(*splash);
> +	if (!splash)
> +		goto err_warn;
> +
> +	mutex_init(&splash->hotplug_lock);
> +	spin_lock_init(&splash->fw_lock);
> +	init_completion(&splash->fw_done);
> +
> +	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");
> +}

-- 
Jani Nikula, Intel