1 files changed, 593 insertions, 104 deletions

diff --git a/drivers/gpu/drm/drm_panic.c b/drivers/gpu/drm/drm_panic.c
index 7ece67086cec..0a9ecc1380d2 100644
--- a/drivers/gpu/drm/drm_panic.c
+++ b/drivers/gpu/drm/drm_panic.c
@@ -7,26 +7,41 @@
  */
 
 #include <linux/font.h>
+#include <linux/init.h>
 #include <linux/iosys-map.h>
 #include <linux/kdebug.h>
 #include <linux/kmsg_dump.h>
+#include <linux/linux_logo.h>
 #include <linux/list.h>
+#include <linux/math.h>
 #include <linux/module.h>
+#include <linux/overflow.h>
+#include <linux/printk.h>
 #include <linux/types.h>
+#include <linux/utsname.h>
+#include <linux/zlib.h>
 
 #include <drm/drm_drv.h>
-#include <drm/drm_format_helper.h>
 #include <drm/drm_fourcc.h>
 #include <drm/drm_framebuffer.h>
 #include <drm/drm_modeset_helper_vtables.h>
 #include <drm/drm_panic.h>
 #include <drm/drm_plane.h>
 #include <drm/drm_print.h>
+#include <drm/drm_rect.h>
+
+#include "drm_crtc_internal.h"
 
 MODULE_AUTHOR("Jocelyn Falempe");
 MODULE_DESCRIPTION("DRM panic handler");
 MODULE_LICENSE("GPL");
 
+static char drm_panic_screen[16] = CONFIG_DRM_PANIC_SCREEN;
+module_param_string(panic_screen, drm_panic_screen, sizeof(drm_panic_screen), 0644);
+MODULE_PARM_DESC(panic_screen,
+		 "Choose what will be displayed by drm_panic, 'user' or 'kmsg' [default="
+		 CONFIG_DRM_PANIC_SCREEN "]");
+
 /**
  * DOC: overview
  *
@@ -66,12 +81,16 @@ struct drm_panic_line {
 #define PANIC_LINE(s) {.len = sizeof(s) - 1, .txt = s}
 
 static struct drm_panic_line panic_msg[] = {
-	PANIC_LINE("KERNEL PANIC !"),
+	PANIC_LINE("KERNEL PANIC!"),
 	PANIC_LINE(""),
 	PANIC_LINE("Please reboot your computer."),
+	PANIC_LINE(""),
+	PANIC_LINE(""), /* will be replaced by the panic description */
 };
 
-static const struct drm_panic_line logo[] = {
+static const size_t panic_msg_lines = ARRAY_SIZE(panic_msg);
+
+static const struct drm_panic_line logo_ascii[] = {
 	PANIC_LINE("     .--.        _"),
 	PANIC_LINE("    |o_o |      | |"),
 	PANIC_LINE("    |:_/ |      | |"),
@@ -81,6 +100,44 @@ static const struct drm_panic_line logo[] = {
 	PANIC_LINE(" \\___)=(___/"),
 };
 
+static const size_t logo_ascii_lines = ARRAY_SIZE(logo_ascii);
+
+#if defined(CONFIG_LOGO) && !defined(MODULE)
+static const struct linux_logo *logo_mono;
+
+static int drm_panic_setup_logo(void)
+{
+	const struct linux_logo *logo = fb_find_logo(1);
+	const unsigned char *logo_data;
+	struct linux_logo *logo_dup;
+
+	if (!logo || logo->type != LINUX_LOGO_MONO)
+		return 0;
+
+	/* The logo is __init, so we must make a copy for later use */
+	logo_data = kmemdup(logo->data,
+			    size_mul(DIV_ROUND_UP(logo->width, BITS_PER_BYTE), logo->height),
+			    GFP_KERNEL);
+	if (!logo_data)
+		return -ENOMEM;
+
+	logo_dup = kmemdup(logo, sizeof(*logo), GFP_KERNEL);
+	if (!logo_dup) {
+		kfree(logo_data);
+		return -ENOMEM;
+	}
+
+	logo_dup->data = logo_data;
+	logo_mono = logo_dup;
+
+	return 0;
+}
+
+device_initcall(drm_panic_setup_logo);
+#else
+#define logo_mono	((const struct linux_logo *)NULL)
+#endif
+
 /*
  * Color conversion
  */
@@ -152,6 +209,14 @@ static u32 convert_xrgb8888_to_argb2101010(u32 pix)
 	return GENMASK(31, 30) /* set alpha bits */ | pix | ((pix >> 8) & 0x00300C03);
 }
 
+static u32 convert_xrgb8888_to_abgr2101010(u32 pix)
+{
+	pix = ((pix & 0x00FF0000) >> 14) |
+	      ((pix & 0x0000FF00) << 4) |
+	      ((pix & 0x000000FF) << 22);
+	return GENMASK(31, 30) /* set alpha bits */ | pix | ((pix >> 8) & 0x00300C03);
+}
+
 /*
  * convert_from_xrgb8888 - convert one pixel from xrgb8888 to the desired format
  * @color: input color, in xrgb8888 format
@@ -185,6 +250,8 @@ static u32 convert_from_xrgb8888(u32 color, u32 format)
 		return convert_xrgb8888_to_xrgb2101010(color);
 	case DRM_FORMAT_ARGB2101010:
 		return convert_xrgb8888_to_argb2101010(color);
+	case DRM_FORMAT_ABGR2101010:
+		return convert_xrgb8888_to_abgr2101010(color);
 	default:
 		WARN_ONCE(1, "Can't convert to %p4cc\n", &format);
 		return 0;
@@ -194,40 +261,42 @@ static u32 convert_from_xrgb8888(u32 color, u32 format)
 /*
  * Blit & Fill
  */
+/* check if the pixel at coord x,y is 1 (foreground) or 0 (background) */
+static bool drm_panic_is_pixel_fg(const u8 *sbuf8, unsigned int spitch, int x, int y)
+{
+	return (sbuf8[(y * spitch) + x / 8] & (0x80 >> (x % 8))) != 0;
+}
+
 static void drm_panic_blit16(struct iosys_map *dmap, unsigned int dpitch,
 			     const u8 *sbuf8, unsigned int spitch,
 			     unsigned int height, unsigned int width,
-			     u16 fg16, u16 bg16)
+			     unsigned int scale, u16 fg16)
 {
 	unsigned int y, x;
-	u16 val16;
 
-	for (y = 0; y < height; y++) {
-		for (x = 0; x < width; x++) {
-			val16 = (sbuf8[(y * spitch) + x / 8] & (0x80 >> (x % 8))) ? fg16 : bg16;
-			iosys_map_wr(dmap, y * dpitch + x * sizeof(u16), u16, val16);
-		}
-	}
+	for (y = 0; y < height; y++)
+		for (x = 0; x < width; x++)
+			if (drm_panic_is_pixel_fg(sbuf8, spitch, x / scale, y / scale))
+				iosys_map_wr(dmap, y * dpitch + x * sizeof(u16), u16, fg16);
 }
 
 static void drm_panic_blit24(struct iosys_map *dmap, unsigned int dpitch,
 			     const u8 *sbuf8, unsigned int spitch,
 			     unsigned int height, unsigned int width,
-			     u32 fg32, u32 bg32)
+			     unsigned int scale, u32 fg32)
 {
 	unsigned int y, x;
-	u32 val32;
 
 	for (y = 0; y < height; y++) {
 		for (x = 0; x < width; x++) {
 			u32 off = y * dpitch + x * 3;
 
-			val32 = (sbuf8[(y * spitch) + x / 8] & (0x80 >> (x % 8))) ? fg32 : bg32;
-
-			/* write blue-green-red to output in little endianness */
-			iosys_map_wr(dmap, off, u8, (val32 & 0x000000FF) >> 0);
-			iosys_map_wr(dmap, off + 1, u8, (val32 & 0x0000FF00) >> 8);
-			iosys_map_wr(dmap, off + 2, u8, (val32 & 0x00FF0000) >> 16);
+			if (drm_panic_is_pixel_fg(sbuf8, spitch, x / scale, y / scale)) {
+				/* write blue-green-red to output in little endianness */
+				iosys_map_wr(dmap, off, u8, (fg32 & 0x000000FF) >> 0);
+				iosys_map_wr(dmap, off + 1, u8, (fg32 & 0x0000FF00) >> 8);
+				iosys_map_wr(dmap, off + 2, u8, (fg32 & 0x00FF0000) >> 16);
+			}
 		}
 	}
 }
@@ -235,55 +304,69 @@ static void drm_panic_blit24(struct iosys_map *dmap, unsigned int dpitch,
 static void drm_panic_blit32(struct iosys_map *dmap, unsigned int dpitch,
 			     const u8 *sbuf8, unsigned int spitch,
 			     unsigned int height, unsigned int width,
-			     u32 fg32, u32 bg32)
+			     unsigned int scale, u32 fg32)
 {
 	unsigned int y, x;
-	u32 val32;
 
-	for (y = 0; y < height; y++) {
-		for (x = 0; x < width; x++) {
-			val32 = (sbuf8[(y * spitch) + x / 8] & (0x80 >> (x % 8))) ? fg32 : bg32;
-			iosys_map_wr(dmap, y * dpitch + x * sizeof(u32), u32, val32);
-		}
-	}
+	for (y = 0; y < height; y++)
+		for (x = 0; x < width; x++)
+			if (drm_panic_is_pixel_fg(sbuf8, spitch, x / scale, y / scale))
+				iosys_map_wr(dmap, y * dpitch + x * sizeof(u32), u32, fg32);
+}
+
+static void drm_panic_blit_pixel(struct drm_scanout_buffer *sb, struct drm_rect *clip,
+				 const u8 *sbuf8, unsigned int spitch, unsigned int scale,
+				 u32 fg_color)
+{
+	unsigned int y, x;
+
+	for (y = 0; y < drm_rect_height(clip); y++)
+		for (x = 0; x < drm_rect_width(clip); x++)
+			if (drm_panic_is_pixel_fg(sbuf8, spitch, x / scale, y / scale))
+				sb->set_pixel(sb, clip->x1 + x, clip->y1 + y, fg_color);
 }
 
 /*
  * drm_panic_blit - convert a monochrome image to a linear framebuffer
- * @dmap: destination iosys_map
- * @dpitch: destination pitch in bytes
+ * @sb: destination scanout buffer
+ * @clip: destination rectangle
  * @sbuf8: source buffer, in monochrome format, 8 pixels per byte.
  * @spitch: source pitch in bytes
- * @height: height of the image to copy, in pixels
- * @width: width of the image to copy, in pixels
+ * @scale: integer scale, source buffer is scale time smaller than destination
+ *         rectangle
  * @fg_color: foreground color, in destination format
- * @bg_color: background color, in destination format
- * @pixel_width: pixel width in bytes.
  *
  * This can be used to draw a font character, which is a monochrome image, to a
  * framebuffer in other supported format.
  */
-static void drm_panic_blit(struct iosys_map *dmap, unsigned int dpitch,
+static void drm_panic_blit(struct drm_scanout_buffer *sb, struct drm_rect *clip,
 			   const u8 *sbuf8, unsigned int spitch,
-			   unsigned int height, unsigned int width,
-			   u32 fg_color, u32 bg_color,
-			   unsigned int pixel_width)
+			   unsigned int scale, u32 fg_color)
+
 {
-	switch (pixel_width) {
+	struct iosys_map map;
+
+	if (sb->set_pixel)
+		return drm_panic_blit_pixel(sb, clip, sbuf8, spitch, scale, fg_color);
+
+	map = sb->map[0];
+	iosys_map_incr(&map, clip->y1 * sb->pitch[0] + clip->x1 * sb->format->cpp[0]);
+
+	switch (sb->format->cpp[0]) {
 	case 2:
-		drm_panic_blit16(dmap, dpitch, sbuf8, spitch,
-				 height, width, fg_color, bg_color);
+		drm_panic_blit16(&map, sb->pitch[0], sbuf8, spitch,
+				 drm_rect_height(clip), drm_rect_width(clip), scale, fg_color);
 	break;
 	case 3:
-		drm_panic_blit24(dmap, dpitch, sbuf8, spitch,
-				 height, width, fg_color, bg_color);
+		drm_panic_blit24(&map, sb->pitch[0], sbuf8, spitch,
+				 drm_rect_height(clip), drm_rect_width(clip), scale, fg_color);
 	break;
 	case 4:
-		drm_panic_blit32(dmap, dpitch, sbuf8, spitch,
-				 height, width, fg_color, bg_color);
+		drm_panic_blit32(&map, sb->pitch[0], sbuf8, spitch,
+				 drm_rect_height(clip), drm_rect_width(clip), scale, fg_color);
 	break;
 	default:
-		WARN_ONCE(1, "Can't blit with pixel width %d\n", pixel_width);
+		WARN_ONCE(1, "Can't blit with pixel width %d\n", sb->format->cpp[0]);
 	}
 }
 
@@ -327,33 +410,51 @@ static void drm_panic_fill32(struct iosys_map *dmap, unsigned int dpitch,
 			iosys_map_wr(dmap, y * dpitch + x * sizeof(u32), u32, color);
 }
 
+static void drm_panic_fill_pixel(struct drm_scanout_buffer *sb,
+				 struct drm_rect *clip,
+				 u32 color)
+{
+	unsigned int y, x;
+
+	for (y = 0; y < drm_rect_height(clip); y++)
+		for (x = 0; x < drm_rect_width(clip); x++)
+			sb->set_pixel(sb, clip->x1 + x, clip->y1 + y, color);
+}
+
 /*
  * drm_panic_fill - Fill a rectangle with a color
- * @dmap: destination iosys_map, pointing to the top left corner of the rectangle
- * @dpitch: destination pitch in bytes
- * @height: height of the rectangle, in pixels
- * @width: width of the rectangle, in pixels
- * @color: color to fill the rectangle.
- * @pixel_width: pixel width in bytes
+ * @sb: destination scanout buffer
+ * @clip: destination rectangle
+ * @color: foreground color, in destination format
  *
  * Fill a rectangle with a color, in a linear framebuffer.
  */
-static void drm_panic_fill(struct iosys_map *dmap, unsigned int dpitch,
-			   unsigned int height, unsigned int width,
-			   u32 color, unsigned int pixel_width)
+static void drm_panic_fill(struct drm_scanout_buffer *sb, struct drm_rect *clip,
+			   u32 color)
 {
-	switch (pixel_width) {
+	struct iosys_map map;
+
+	if (sb->set_pixel)
+		return drm_panic_fill_pixel(sb, clip, color);
+
+	map = sb->map[0];
+	iosys_map_incr(&map, clip->y1 * sb->pitch[0] + clip->x1 * sb->format->cpp[0]);
+
+	switch (sb->format->cpp[0]) {
 	case 2:
-		drm_panic_fill16(dmap, dpitch, height, width, color);
+		drm_panic_fill16(&map, sb->pitch[0], drm_rect_height(clip),
+				 drm_rect_width(clip), color);
 	break;
 	case 3:
-		drm_panic_fill24(dmap, dpitch, height, width, color);
+		drm_panic_fill24(&map, sb->pitch[0], drm_rect_height(clip),
+				 drm_rect_width(clip), color);
 	break;
 	case 4:
-		drm_panic_fill32(dmap, dpitch, height, width, color);
+		drm_panic_fill32(&map, sb->pitch[0], drm_rect_height(clip),
+				 drm_rect_width(clip), color);
 	break;
 	default:
-		WARN_ONCE(1, "Can't fill with pixel width %d\n", pixel_width);
+		WARN_ONCE(1, "Can't fill with pixel width %d\n", sb->format->cpp[0]);
 	}
 }
 
@@ -381,76 +482,392 @@ static void draw_txt_rectangle(struct drm_scanout_buffer *sb,
 			       unsigned int msg_lines,
 			       bool centered,
 			       struct drm_rect *clip,
-			       u32 fg_color,
-			       u32 bg_color)
+			       u32 color)
 {
 	int i, j;
 	const u8 *src;
 	size_t font_pitch = DIV_ROUND_UP(font->width, 8);
-	struct iosys_map dst;
-	unsigned int px_width = sb->format->cpp[0];
-	int left = 0;
+	struct drm_rect rec;
 
 	msg_lines = min(msg_lines,  drm_rect_height(clip) / font->height);
 	for (i = 0; i < msg_lines; i++) {
 		size_t line_len = min(msg[i].len, drm_rect_width(clip) / font->width);
 
+		rec.y1 = clip->y1 +  i * font->height;
+		rec.y2 = rec.y1 + font->height;
+		rec.x1 = clip->x1;
+
 		if (centered)
-			left = (drm_rect_width(clip) - (line_len * font->width)) / 2;
+			rec.x1 += (drm_rect_width(clip) - (line_len * font->width)) / 2;
 
-		dst = sb->map[0];
-		iosys_map_incr(&dst, (clip->y1 + i * font->height) * sb->pitch[0] +
-				     (clip->x1 + left) * px_width);
 		for (j = 0; j < line_len; j++) {
 			src = get_char_bitmap(font, msg[i].txt[j], font_pitch);
-			drm_panic_blit(&dst, sb->pitch[0], src, font_pitch,
-				       font->height, font->width,
-				       fg_color, bg_color, px_width);
-			iosys_map_incr(&dst, font->width * px_width);
+			rec.x2 = rec.x1 + font->width;
+			drm_panic_blit(sb, &rec, src, font_pitch, 1, color);
+			rec.x1 += font->width;
 		}
 	}
 }
 
-/*
- * Draw the panic message at the center of the screen
- */
-static void draw_panic_static(struct drm_scanout_buffer *sb)
+static void drm_panic_logo_rect(struct drm_rect *rect, const struct font_desc *font)
+{
+	if (logo_mono) {
+		drm_rect_init(rect, 0, 0, logo_mono->width, logo_mono->height);
+	} else {
+		int logo_width = get_max_line_len(logo_ascii, logo_ascii_lines) * font->width;
+
+		drm_rect_init(rect, 0, 0, logo_width, logo_ascii_lines * font->height);
+	}
+}
+
+static void drm_panic_logo_draw(struct drm_scanout_buffer *sb, struct drm_rect *rect,
+				const struct font_desc *font, u32 fg_color)
 {
-	size_t msg_lines = ARRAY_SIZE(panic_msg);
-	size_t logo_lines = ARRAY_SIZE(logo);
-	u32 fg_color = CONFIG_DRM_PANIC_FOREGROUND_COLOR;
-	u32 bg_color = CONFIG_DRM_PANIC_BACKGROUND_COLOR;
+	if (logo_mono)
+		drm_panic_blit(sb, rect, logo_mono->data,
+			       DIV_ROUND_UP(drm_rect_width(rect), 8), 1, fg_color);
+	else
+		draw_txt_rectangle(sb, font, logo_ascii, logo_ascii_lines, false, rect,
+				   fg_color);
+}
+
+static void draw_panic_static_user(struct drm_scanout_buffer *sb)
+{
+	u32 fg_color = convert_from_xrgb8888(CONFIG_DRM_PANIC_FOREGROUND_COLOR, sb->format->format);
+	u32 bg_color = convert_from_xrgb8888(CONFIG_DRM_PANIC_BACKGROUND_COLOR, sb->format->format);
 	const struct font_desc *font = get_default_font(sb->width, sb->height, NULL, NULL);
-	struct drm_rect r_logo, r_msg;
+	struct drm_rect r_screen, r_logo, r_msg;
+	unsigned int msg_width, msg_height;
 
 	if (!font)
 		return;
 
-	fg_color = convert_from_xrgb8888(fg_color, sb->format->format);
-	bg_color = convert_from_xrgb8888(bg_color, sb->format->format);
+	r_screen = DRM_RECT_INIT(0, 0, sb->width, sb->height);
+	drm_panic_logo_rect(&r_logo, font);
 
-	r_logo = DRM_RECT_INIT(0, 0,
-			       get_max_line_len(logo, logo_lines) * font->width,
-			       logo_lines * font->height);
-	r_msg = DRM_RECT_INIT(0, 0,
-			      min(get_max_line_len(panic_msg, msg_lines) * font->width, sb->width),
-			      min(msg_lines * font->height, sb->height));
+	msg_width = min(get_max_line_len(panic_msg, panic_msg_lines) * font->width, sb->width);
+	msg_height = min(panic_msg_lines * font->height, sb->height);
+	r_msg = DRM_RECT_INIT(0, 0, msg_width, msg_height);
 
 	/* Center the panic message */
 	drm_rect_translate(&r_msg, (sb->width - r_msg.x2) / 2, (sb->height - r_msg.y2) / 2);
 
 	/* Fill with the background color, and draw text on top */
-	drm_panic_fill(&sb->map[0], sb->pitch[0], sb->height, sb->width,
-		       bg_color, sb->format->cpp[0]);
+	drm_panic_fill(sb, &r_screen, bg_color);
+
+	if (!drm_rect_overlap(&r_logo, &r_msg))
+		drm_panic_logo_draw(sb, &r_logo, font, fg_color);
+
+	draw_txt_rectangle(sb, font, panic_msg, panic_msg_lines, true, &r_msg, fg_color);
+}
 
-	if ((r_msg.x1 >= drm_rect_width(&r_logo) || r_msg.y1 >= drm_rect_height(&r_logo)) &&
-	    drm_rect_width(&r_logo) < sb->width && drm_rect_height(&r_logo) < sb->height) {
-		draw_txt_rectangle(sb, font, logo, logo_lines, false, &r_logo, fg_color, bg_color);
+/*
+ * Draw one line of kmsg, and handle wrapping if it won't fit in the screen width.
+ * Return the y-offset of the next line.
+ */
+static int draw_line_with_wrap(struct drm_scanout_buffer *sb, const struct font_desc *font,
+			       struct drm_panic_line *line, int yoffset, u32 fg_color)
+{
+	int chars_per_row = sb->width / font->width;
+	struct drm_rect r_txt = DRM_RECT_INIT(0, yoffset, sb->width, sb->height);
+	struct drm_panic_line line_wrap;
+
+	if (line->len > chars_per_row) {
+		line_wrap.len = line->len % chars_per_row;
+		line_wrap.txt = line->txt + line->len - line_wrap.len;
+		draw_txt_rectangle(sb, font, &line_wrap, 1, false, &r_txt, fg_color);
+		r_txt.y1 -= font->height;
+		if (r_txt.y1 < 0)
+			return r_txt.y1;
+		while (line_wrap.txt > line->txt) {
+			line_wrap.txt -= chars_per_row;
+			line_wrap.len = chars_per_row;
+			draw_txt_rectangle(sb, font, &line_wrap, 1, false, &r_txt, fg_color);
+			r_txt.y1 -= font->height;
+			if (r_txt.y1 < 0)
+				return r_txt.y1;
+		}
+	} else {
+		draw_txt_rectangle(sb, font, line, 1, false, &r_txt, fg_color);
+		r_txt.y1 -= font->height;
 	}
-	draw_txt_rectangle(sb, font, panic_msg, msg_lines, true, &r_msg, fg_color, bg_color);
+	return r_txt.y1;
 }
 
 /*
+ * Draw the kmsg buffer to the screen, starting from the youngest message at the bottom,
+ * and going up until reaching the top of the screen.
+ */
+static void draw_panic_static_kmsg(struct drm_scanout_buffer *sb)
+{
+	u32 fg_color = convert_from_xrgb8888(CONFIG_DRM_PANIC_FOREGROUND_COLOR, sb->format->format);
+	u32 bg_color = convert_from_xrgb8888(CONFIG_DRM_PANIC_BACKGROUND_COLOR, sb->format->format);
+	const struct font_desc *font = get_default_font(sb->width, sb->height, NULL, NULL);
+	struct drm_rect r_screen = DRM_RECT_INIT(0, 0, sb->width, sb->height);
+	struct kmsg_dump_iter iter;
+	char kmsg_buf[512];
+	size_t kmsg_len;
+	struct drm_panic_line line;
+	int yoffset;
+
+	if (!font)
+		return;
+
+	yoffset = sb->height - font->height - (sb->height % font->height) / 2;
+
+	/* Fill with the background color, and draw text on top */
+	drm_panic_fill(sb, &r_screen, bg_color);
+
+	kmsg_dump_rewind(&iter);
+	while (kmsg_dump_get_buffer(&iter, false, kmsg_buf, sizeof(kmsg_buf), &kmsg_len)) {
+		char *start;
+		char *end;
+
+		/* ignore terminating NUL and newline */
+		start = kmsg_buf + kmsg_len - 2;
+		end = kmsg_buf + kmsg_len - 1;
+		while (start > kmsg_buf && yoffset >= 0) {
+			while (start > kmsg_buf && *start != '\n')
+				start--;
+			/* don't count the newline character */
+			line.txt = start + (start == kmsg_buf ? 0 : 1);
+			line.len = end - line.txt;
+
+			yoffset = draw_line_with_wrap(sb, font, &line, yoffset, fg_color);
+			end = start;
+			start--;
+		}
+	}
+}
+
+#if defined(CONFIG_DRM_PANIC_SCREEN_QR_CODE)
+/*
+ * It is unwise to allocate memory in the panic callback, so the buffers are
+ * pre-allocated. Only 2 buffers and the zlib workspace are needed.
+ * Two buffers are enough, using the following buffer usage:
+ * 1) kmsg messages are dumped in buffer1
+ * 2) kmsg is zlib-compressed into buffer2
+ * 3) compressed kmsg is encoded as QR-code Numeric stream in buffer1
+ * 4) QR-code image is generated in buffer2
+ * The Max QR code size is V40, 177x177, 4071 bytes for image, 2956 bytes for
+ * data segments.
+ *
+ * Typically, ~7500 bytes of kmsg, are compressed into 2800 bytes, which fits in
+ * a V40 QR-code (177x177).
+ *
+ * If CONFIG_DRM_PANIC_SCREEN_QR_CODE_URL is not set, the kmsg data will be put
+ * directly in the QR code.
+ * 1) kmsg messages are dumped in buffer1
+ * 2) kmsg message is encoded as byte stream in buffer2
+ * 3) QR-code image is generated in buffer1
+ */
+
+static uint panic_qr_version = CONFIG_DRM_PANIC_SCREEN_QR_VERSION;
+module_param(panic_qr_version, uint, 0644);
+MODULE_PARM_DESC(panic_qr_version, "maximum version (size) of the QR code");
+
+#define MAX_QR_DATA 2956
+#define MAX_ZLIB_RATIO 3
+#define QR_BUFFER1_SIZE (MAX_ZLIB_RATIO * MAX_QR_DATA) /* Must also be > 4071  */
+#define QR_BUFFER2_SIZE 4096
+#define QR_MARGIN	4	/* 4 modules of foreground color around the qr code */
+
+/* Compression parameters */
+#define COMPR_LEVEL 6
+#define WINDOW_BITS 12
+#define MEM_LEVEL 4
+
+static char *qrbuf1;
+static char *qrbuf2;
+static struct z_stream_s stream;
+
+static void __init drm_panic_qr_init(void)
+{
+	qrbuf1 = kmalloc(QR_BUFFER1_SIZE, GFP_KERNEL);
+	qrbuf2 = kmalloc(QR_BUFFER2_SIZE, GFP_KERNEL);
+	stream.workspace = kmalloc(zlib_deflate_workspacesize(WINDOW_BITS, MEM_LEVEL),
+				   GFP_KERNEL);
+}
+
+static void drm_panic_qr_exit(void)
+{
+	kfree(qrbuf1);
+	qrbuf1 = NULL;
+	kfree(qrbuf2);
+	qrbuf2 = NULL;
+	kfree(stream.workspace);
+	stream.workspace = NULL;
+}
+
+extern size_t drm_panic_qr_max_data_size(u8 version, size_t url_len);
+
+extern u8 drm_panic_qr_generate(const char *url, u8 *data, size_t data_len, size_t data_size,
+				u8 *tmp, size_t tmp_size);
+
+static int drm_panic_get_qr_code_url(u8 **qr_image)
+{
+	struct kmsg_dump_iter iter;
+	char url[256];
+	size_t kmsg_len, max_kmsg_size;
+	char *kmsg;
+	int max_qr_data_size, url_len;
+
+	url_len = snprintf(url, sizeof(url), CONFIG_DRM_PANIC_SCREEN_QR_CODE_URL "?a=%s&v=%s&zl=",
+			   utsname()->machine, utsname()->release);
+
+	max_qr_data_size = drm_panic_qr_max_data_size(panic_qr_version, url_len);
+	max_kmsg_size = min(MAX_ZLIB_RATIO * max_qr_data_size, QR_BUFFER1_SIZE);
+
+	/* get kmsg to buffer 1 */
+	kmsg_dump_rewind(&iter);
+	kmsg_dump_get_buffer(&iter, false, qrbuf1, max_kmsg_size, &kmsg_len);
+
+	if (!kmsg_len)
+		return -ENODATA;
+	kmsg = qrbuf1;
+
+try_again:
+	if (zlib_deflateInit2(&stream, COMPR_LEVEL, Z_DEFLATED, WINDOW_BITS,
+			      MEM_LEVEL, Z_DEFAULT_STRATEGY) != Z_OK)
+		return -EINVAL;
+
+	stream.next_in = kmsg;
+	stream.avail_in = kmsg_len;
+	stream.total_in = 0;
+	stream.next_out = qrbuf2;
+	stream.avail_out = QR_BUFFER2_SIZE;
+	stream.total_out = 0;
+
+	if (zlib_deflate(&stream, Z_FINISH) != Z_STREAM_END)
+		return -EINVAL;
+
+	if (zlib_deflateEnd(&stream) != Z_OK)
+		return -EINVAL;
+
+	if (stream.total_out > max_qr_data_size) {
+		/* too much data for the QR code, so skip the first line and try again */
+		kmsg = strchr(kmsg, '\n');
+		if (!kmsg)
+			return -EINVAL;
+		/* skip the first \n */
+		kmsg += 1;
+		kmsg_len = strlen(kmsg);
+		goto try_again;
+	}
+	*qr_image = qrbuf2;
+
+	/* generate qr code image in buffer2 */
+	return drm_panic_qr_generate(url, qrbuf2, stream.total_out, QR_BUFFER2_SIZE,
+				     qrbuf1, QR_BUFFER1_SIZE);
+}
+
+static int drm_panic_get_qr_code_raw(u8 **qr_image)
+{
+	struct kmsg_dump_iter iter;
+	size_t kmsg_len;
+	size_t max_kmsg_size = min(drm_panic_qr_max_data_size(panic_qr_version, 0),
+				   QR_BUFFER1_SIZE);
+
+	kmsg_dump_rewind(&iter);
+	kmsg_dump_get_buffer(&iter, false, qrbuf1, max_kmsg_size, &kmsg_len);
+	if (!kmsg_len)
+		return -ENODATA;
+
+	*qr_image = qrbuf1;
+	return drm_panic_qr_generate(NULL, qrbuf1, kmsg_len, QR_BUFFER1_SIZE,
+				     qrbuf2, QR_BUFFER2_SIZE);
+}
+
+static int drm_panic_get_qr_code(u8 **qr_image)
+{
+	if (strlen(CONFIG_DRM_PANIC_SCREEN_QR_CODE_URL) > 0)
+		return drm_panic_get_qr_code_url(qr_image);
+	else
+		return drm_panic_get_qr_code_raw(qr_image);
+}
+
+/*
+ * Draw the panic message at the center of the screen, with a QR Code
+ */
+static int _draw_panic_static_qr_code(struct drm_scanout_buffer *sb)
+{
+	u32 fg_color = convert_from_xrgb8888(CONFIG_DRM_PANIC_FOREGROUND_COLOR, sb->format->format);
+	u32 bg_color = convert_from_xrgb8888(CONFIG_DRM_PANIC_BACKGROUND_COLOR, sb->format->format);
+	const struct font_desc *font = get_default_font(sb->width, sb->height, NULL, NULL);
+	struct drm_rect r_screen, r_logo, r_msg, r_qr, r_qr_canvas;
+	unsigned int max_qr_size, scale;
+	unsigned int msg_width, msg_height;
+	int qr_width, qr_canvas_width, qr_pitch, v_margin;
+	u8 *qr_image;
+
+	if (!font || !qrbuf1 || !qrbuf2 || !stream.workspace)
+		return -ENOMEM;
+
+	r_screen = DRM_RECT_INIT(0, 0, sb->width, sb->height);
+
+	drm_panic_logo_rect(&r_logo, font);
+
+	msg_width = min(get_max_line_len(panic_msg, panic_msg_lines) * font->width, sb->width);
+	msg_height = min(panic_msg_lines * font->height, sb->height);
+	r_msg = DRM_RECT_INIT(0, 0, msg_width, msg_height);
+
+	max_qr_size = min(3 * sb->width / 4, 3 * sb->height / 4);
+
+	qr_width = drm_panic_get_qr_code(&qr_image);
+	if (qr_width <= 0)
+		return -ENOSPC;
+
+	qr_canvas_width = qr_width + QR_MARGIN * 2;
+	scale = max_qr_size / qr_canvas_width;
+	/* QR code is not readable if not scaled at least by 2 */
+	if (scale < 2)
+		return -ENOSPC;
+
+	pr_debug("QR width %d and scale %d\n", qr_width, scale);
+	r_qr_canvas = DRM_RECT_INIT(0, 0, qr_canvas_width * scale, qr_canvas_width * scale);
+
+	v_margin = (sb->height - drm_rect_height(&r_qr_canvas) - drm_rect_height(&r_msg)) / 5;
+
+	drm_rect_translate(&r_qr_canvas, (sb->width - r_qr_canvas.x2) / 2, 2 * v_margin);
+	r_qr = DRM_RECT_INIT(r_qr_canvas.x1 + QR_MARGIN * scale, r_qr_canvas.y1 + QR_MARGIN * scale,
+			     qr_width * scale, qr_width * scale);
+
+	/* Center the panic message */
+	drm_rect_translate(&r_msg, (sb->width - r_msg.x2) / 2,
+			   3 * v_margin + drm_rect_height(&r_qr_canvas));
+
+	/* Fill with the background color, and draw text on top */
+	drm_panic_fill(sb, &r_screen, bg_color);
+
+	if (!drm_rect_overlap(&r_logo, &r_msg) && !drm_rect_overlap(&r_logo, &r_qr))
+		drm_panic_logo_draw(sb, &r_logo, font, fg_color);
+
+	draw_txt_rectangle(sb, font, panic_msg, panic_msg_lines, true, &r_msg, fg_color);
+
+	/* Draw the qr code */
+	qr_pitch = DIV_ROUND_UP(qr_width, 8);
+	drm_panic_fill(sb, &r_qr_canvas, fg_color);
+	drm_panic_fill(sb, &r_qr, bg_color);
+	drm_panic_blit(sb, &r_qr, qr_image, qr_pitch, scale, fg_color);
+	return 0;
+}
+
+static void draw_panic_static_qr_code(struct drm_scanout_buffer *sb)
+{
+	if (_draw_panic_static_qr_code(sb))
+		draw_panic_static_user(sb);
+}
+#else
+static void draw_panic_static_qr_code(struct drm_scanout_buffer *sb)
+{
+	draw_panic_static_user(sb);
+}
+
+static void drm_panic_qr_init(void) {};
+static void drm_panic_qr_exit(void) {};
+#endif
+
+/*
  * drm_panic_is_format_supported()
  * @format: a fourcc color code
  * Returns: true if supported, false otherwise.
@@ -464,22 +881,60 @@ static bool drm_panic_is_format_supported(const struct drm_format_info *format)
 	return convert_from_xrgb8888(0xffffff, format->format) != 0;
 }
 
-static void draw_panic_plane(struct drm_plane *plane)
+static void draw_panic_dispatch(struct drm_scanout_buffer *sb)
+{
+	if (!strcmp(drm_panic_screen, "kmsg")) {
+		draw_panic_static_kmsg(sb);
+	} else if (!strcmp(drm_panic_screen, "qr_code")) {
+		draw_panic_static_qr_code(sb);
+	} else {
+		draw_panic_static_user(sb);
+	}
+}
+
+static void drm_panic_set_description(const char *description)
+{
+	u32 len;
+
+	if (description) {
+		struct drm_panic_line *desc_line = &panic_msg[panic_msg_lines - 1];
+
+		desc_line->txt = description;
+		len = strlen(description);
+		/* ignore the last newline character */
+		if (len && description[len - 1] == '\n')
+			len -= 1;
+		desc_line->len = len;
+	}
+}
+
+static void drm_panic_clear_description(void)
+{
+	struct drm_panic_line *desc_line = &panic_msg[panic_msg_lines - 1];
+
+	desc_line->len = 0;
+	desc_line->txt = NULL;
+}
+
+static void draw_panic_plane(struct drm_plane *plane, const char *description)
 {
-	struct drm_scanout_buffer sb;
+	struct drm_scanout_buffer sb = { };
 	int ret;
 	unsigned long flags;
 
 	if (!drm_panic_trylock(plane->dev, flags))
 		return;
 
+	drm_panic_set_description(description);
+
 	ret = plane->helper_private->get_scanout_buffer(plane, &sb);
 
 	if (!ret && drm_panic_is_format_supported(sb.format)) {
-		draw_panic_static(&sb);
+		draw_panic_dispatch(&sb);
 		if (plane->helper_private->panic_flush)
 			plane->helper_private->panic_flush(plane);
 	}
+	drm_panic_clear_description();
 	drm_panic_unlock(plane->dev, flags);
 }
 
@@ -488,12 +943,12 @@ static struct drm_plane *to_drm_plane(struct kmsg_dumper *kd)
 	return container_of(kd, struct drm_plane, kmsg_panic);
 }
 
-static void drm_panic(struct kmsg_dumper *dumper, enum kmsg_dump_reason reason)
+static void drm_panic(struct kmsg_dumper *dumper, struct kmsg_dump_detail *detail)
 {
 	struct drm_plane *plane = to_drm_plane(dumper);
 
-	if (reason == KMSG_DUMP_PANIC)
-		draw_panic_plane(plane);
+	if (detail->reason == KMSG_DUMP_PANIC)
+		draw_panic_plane(plane, detail->description);
 }
 
 
@@ -513,7 +968,7 @@ static ssize_t debugfs_trigger_write(struct file *file, const char __user *user_
 	if (kstrtobool_from_user(user_buf, count, &run) == 0 && run) {
 		struct drm_plane *plane = file->private_data;
 
-		draw_panic_plane(plane);
+		draw_panic_plane(plane, "Test from debugfs");
 	}
 	return count;
 }
@@ -537,6 +992,26 @@ static void debugfs_register_plane(struct drm_plane *plane, int index) {}
 #endif /* CONFIG_DRM_PANIC_DEBUG */
 
 /**
+ * drm_panic_is_enabled
+ * @dev: the drm device that may supports drm_panic
+ *
+ * returns true if the drm device supports drm_panic
+ */
+bool drm_panic_is_enabled(struct drm_device *dev)
+{
+	struct drm_plane *plane;
+
+	if (!dev->mode_config.num_total_plane)
+		return false;
+
+	drm_for_each_plane(plane, dev)
+		if (plane->helper_private && plane->helper_private->get_scanout_buffer)
+			return true;
+	return false;
+}
+EXPORT_SYMBOL(drm_panic_is_enabled);
+
+/**
  * drm_panic_register() - Initialize DRM panic for a device
  * @dev: the drm device on which the panic screen will be displayed.
  */
@@ -563,7 +1038,6 @@ void drm_panic_register(struct drm_device *dev)
 	if (registered_plane)
 		drm_info(dev, "Registered %d planes with drm panic\n", registered_plane);
 }
-EXPORT_SYMBOL(drm_panic_register);
 
 /**
  * drm_panic_unregister()
@@ -582,4 +1056,19 @@ void drm_panic_unregister(struct drm_device *dev)
 		kmsg_dump_unregister(&plane->kmsg_panic);
 	}
 }
-EXPORT_SYMBOL(drm_panic_unregister);
+
+/**
+ * drm_panic_init() - initialize DRM panic.
+ */
+void __init drm_panic_init(void)
+{
+	drm_panic_qr_init();
+}
+
+/**
+ * drm_panic_exit() - Free the resources taken by drm_panic_exit()
+ */
+void drm_panic_exit(void)
+{
+	drm_panic_qr_exit();
+}