[PATCH v12 2/9] drm/panic: Add a drm panic handler
Jocelyn Falempe
jfalempe at redhat.com
Wed Apr 10 15:14:41 UTC 2024
Hi,
On 10/04/2024 10:10, Daniel Vetter wrote:
> On Tue, Apr 09, 2024 at 06:30:41PM +0200, Jocelyn Falempe wrote:
>> This module displays a user friendly message when a kernel panic
>> occurs. It currently doesn't contain any debug information,
>> but that can be added later.
>>
>> v2
>> * Use get_scanout_buffer() instead of the drm client API.
>> (Thomas Zimmermann)
>> * Add the panic reason to the panic message (Nerdopolis)
>> * Add an exclamation mark (Nerdopolis)
>>
>> v3
>> * Rework the drawing functions, to write the pixels line by line and
>> to use the drm conversion helper to support other formats.
>> (Thomas Zimmermann)
>>
>> v4
>> * Use drm_fb_r1_to_32bit for fonts (Thomas Zimmermann)
>> * Remove the default y to DRM_PANIC config option (Thomas Zimmermann)
>> * Add foreground/background color config option
>> * Fix the bottom lines not painted if the framebuffer height
>> is not a multiple of the font height.
>> * Automatically register the device to drm_panic, if the function
>> get_scanout_buffer exists. (Thomas Zimmermann)
>>
>> v5
>> * Change the drawing API, use drm_fb_blit_from_r1() to draw the font.
>> * Also add drm_fb_fill() to fill area with background color.
>> * Add draw_pixel_xy() API for drivers that can't provide a linear buffer.
>> * Add a flush() callback for drivers that needs to synchronize the buffer.
>> * Add a void *private field, so drivers can pass private data to
>> draw_pixel_xy() and flush().
>>
>> v6
>> * Fix sparse warning for panic_msg and logo.
>>
>> v7
>> * Add select DRM_KMS_HELPER for the color conversion functions.
>>
>> v8
>> * Register directly each plane to the panic notifier (Sima)
>> * Add raw_spinlock to properly handle concurrency (Sima)
>> * Register plane instead of device, to avoid looping through plane
>> list, and simplify code.
>> * Replace get_scanout_buffer() logic with drm_panic_set_buffer()
>> (Thomas Zimmermann)
>> * Removed the draw_pixel_xy() API, will see later if it can be added back.
>>
>> v9
>> * Revert to using get_scanout_buffer() (Sima)
>> * Move get_scanout_buffer() and panic_flush() to the plane helper
>> functions (Thomas Zimmermann)
>> * Register all planes with get_scanout_buffer() to the panic notifier
>> * Use drm_panic_lock() to protect against race (Sima)
>>
>> v10
>> * Move blit and fill functions back in drm_panic (Thomas Zimmermann).
>> * Simplify the text drawing functions.
>> * Use kmsg_dumper instead of panic_notifier (Sima).
>>
>> v12
>> * Use array for map and pitch in struct drm_scanout_buffer
>> to support multi-planar format later. (Thomas Zimmermann)
>> * Better indent struct drm_scanout_buffer declaration. (Thomas Zimmermann)
>>
>> Signed-off-by: Jocelyn Falempe <jfalempe at redhat.com>
>
> Some detail suggestions for the kerneldoc but those aside Acked-by: Daniel
> Vetter <daniel.vetter at ffwll.ch>
Thanks for the review.
I fixed the documentation, and make sure the links are working.
>> ---
>> Documentation/gpu/drm-kms.rst | 12 +
>> drivers/gpu/drm/Kconfig | 23 ++
>> drivers/gpu/drm/Makefile | 1 +
>> drivers/gpu/drm/drm_drv.c | 4 +
>> drivers/gpu/drm/drm_panic.c | 289 +++++++++++++++++++++++
>> include/drm/drm_modeset_helper_vtables.h | 37 +++
>> include/drm/drm_panic.h | 57 +++++
>> include/drm/drm_plane.h | 6 +
>> 8 files changed, 429 insertions(+)
>> create mode 100644 drivers/gpu/drm/drm_panic.c
>>
>> diff --git a/Documentation/gpu/drm-kms.rst b/Documentation/gpu/drm-kms.rst
>> index 13d3627d8bc0..b64334661aeb 100644
>> --- a/Documentation/gpu/drm-kms.rst
>> +++ b/Documentation/gpu/drm-kms.rst
>> @@ -398,6 +398,18 @@ Plane Damage Tracking Functions Reference
>> .. kernel-doc:: include/drm/drm_damage_helper.h
>> :internal:
>>
>> +Plane Panic Feature
>> +-------------------
>> +
>> +.. kernel-doc:: drivers/gpu/drm/drm_panic.c
>> + :doc: overview
>> +
>> +Plane Panic Functions Reference
>> +-------------------------------
>> +
>> +.. kernel-doc:: drivers/gpu/drm/drm_panic.c
>> + :export:
>> +
>> Display Modes Function Reference
>> ================================
>>
>> diff --git a/drivers/gpu/drm/Kconfig b/drivers/gpu/drm/Kconfig
>> index 3914aaf443a8..f8a26423369e 100644
>> --- a/drivers/gpu/drm/Kconfig
>> +++ b/drivers/gpu/drm/Kconfig
>> @@ -104,6 +104,29 @@ config DRM_KMS_HELPER
>> help
>> CRTC helpers for KMS drivers.
>>
>> +config DRM_PANIC
>> + bool "Display a user-friendly message when a kernel panic occurs"
>> + depends on DRM && !FRAMEBUFFER_CONSOLE
>> + select DRM_KMS_HELPER
>> + select FONT_SUPPORT
>> + help
>> + Enable a drm panic handler, which will display a user-friendly message
>> + when a kernel panic occurs. It's useful when using a user-space
>> + console instead of fbcon.
>> + It will only work if your graphic driver supports this feature.
>> + To support Hi-DPI Display, you can enable bigger fonts like
>> + FONT_TER16x32
>> +
>> +config DRM_PANIC_FOREGROUND_COLOR
>> + hex "Drm panic screen foreground color, in RGB"
>> + depends on DRM_PANIC
>> + default 0xffffff
>> +
>> +config DRM_PANIC_BACKGROUND_COLOR
>> + hex "Drm panic screen background color, in RGB"
>> + depends on DRM_PANIC
>> + default 0x000000
>> +
>> config DRM_DEBUG_DP_MST_TOPOLOGY_REFS
>> bool "Enable refcount backtrace history in the DP MST helpers"
>> depends on STACKTRACE_SUPPORT
>> diff --git a/drivers/gpu/drm/Makefile b/drivers/gpu/drm/Makefile
>> index a73c04d2d7a3..f9ca4f8fa6c5 100644
>> --- a/drivers/gpu/drm/Makefile
>> +++ b/drivers/gpu/drm/Makefile
>> @@ -88,6 +88,7 @@ drm-$(CONFIG_DRM_PRIVACY_SCREEN) += \
>> drm_privacy_screen.o \
>> drm_privacy_screen_x86.o
>> drm-$(CONFIG_DRM_ACCEL) += ../../accel/drm_accel.o
>> +drm-$(CONFIG_DRM_PANIC) += drm_panic.o
>> obj-$(CONFIG_DRM) += drm.o
>>
>> obj-$(CONFIG_DRM_PANEL_ORIENTATION_QUIRKS) += drm_panel_orientation_quirks.o
>> diff --git a/drivers/gpu/drm/drm_drv.c b/drivers/gpu/drm/drm_drv.c
>> index c157500b3135..535b624d4c9d 100644
>> --- a/drivers/gpu/drm/drm_drv.c
>> +++ b/drivers/gpu/drm/drm_drv.c
>> @@ -43,6 +43,7 @@
>> #include <drm/drm_file.h>
>> #include <drm/drm_managed.h>
>> #include <drm/drm_mode_object.h>
>> +#include <drm/drm_panic.h>
>> #include <drm/drm_print.h>
>> #include <drm/drm_privacy_screen_machine.h>
>>
>> @@ -944,6 +945,7 @@ int drm_dev_register(struct drm_device *dev, unsigned long flags)
>> if (ret)
>> goto err_unload;
>> }
>> + drm_panic_register(dev);
>>
>> DRM_INFO("Initialized %s %d.%d.%d %s for %s on minor %d\n",
>> driver->name, driver->major, driver->minor,
>> @@ -988,6 +990,8 @@ void drm_dev_unregister(struct drm_device *dev)
>> {
>> dev->registered = false;
>>
>> + drm_panic_unregister(dev);
>> +
>> drm_client_dev_unregister(dev);
>>
>> if (drm_core_check_feature(dev, DRIVER_MODESET))
>> diff --git a/drivers/gpu/drm/drm_panic.c b/drivers/gpu/drm/drm_panic.c
>> new file mode 100644
>> index 000000000000..fa4b220534a4
>> --- /dev/null
>> +++ b/drivers/gpu/drm/drm_panic.c
>> @@ -0,0 +1,289 @@
>> +// SPDX-License-Identifier: GPL-2.0 or MIT
>> +/*
>> + * Copyright (c) 2023 Red Hat.
>> + * Author: Jocelyn Falempe <jfalempe at redhat.com>
>> + * inspired by the drm_log driver from David Herrmann <dh.herrmann at gmail.com>
>> + * Tux Ascii art taken from cowsay written by Tony Monroe
>> + */
>> +
>> +#include <linux/font.h>
>> +#include <linux/iosys-map.h>
>> +#include <linux/kdebug.h>
>> +#include <linux/kmsg_dump.h>
>> +#include <linux/list.h>
>> +#include <linux/module.h>
>> +#include <linux/types.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>
>> +
>> +
>> +MODULE_AUTHOR("Jocelyn Falempe");
>> +MODULE_DESCRIPTION("DRM panic handler");
>> +MODULE_LICENSE("GPL");
>> +
>> +/**
>> + * DOC: overview
>> + *
>> + * To enable DRM panic for a driver, the primary plane must implement a
>> + * get_scanout_buffer() helper function. It is then automatically registered to
>> + * the drm panic handler.
>> + * When a panic occurs, the get_scanout_buffer() will be called, and the driver
>> + * can provide a framebuffer so the panic handler can draw the panic screen on
>> + * it. The buffer provided must be linear, and use a supported color format.
>> + * Optionally the driver can also provide a panic_flush() callback, that will
>> + * be called after that, to send additional commands to the hardware to make the
>> + * scanout buffer visible.
>> + */
>> +
>> +/*
>> + * This module displays a user friendly message on screen when a kernel panic
>> + * occurs. This is conflicting with fbcon, so you can only enable it when fbcon
>> + * is disabled.
>> + * It's intended for end-user, so have minimal technical/debug information.
>> + *
>> + * Implementation details:
>> + *
>> + * It is a panic handler, so it can't take lock, allocate memory, run tasks/irq,
>> + * or attempt to sleep. It's a best effort, and it may not be able to display
>> + * the message in all situations (like if the panic occurs in the middle of a
>> + * modesetting).
>> + * It will display only one static frame, so performance optimizations are low
>> + * priority as the machine is already in an unusable state.
>> + */
>> +
>> +struct drm_panic_line {
>> + u32 len;
>> + const char *txt;
>> +};
>> +
>> +#define PANIC_LINE(s) {.len = sizeof(s) - 1, .txt = s}
>> +
>> +static struct drm_panic_line panic_msg[] = {
>> + PANIC_LINE("KERNEL PANIC !"),
>> + PANIC_LINE(""),
>> + PANIC_LINE("Please reboot your computer."),
>> +};
>> +
>> +static const struct drm_panic_line logo[] = {
>> + PANIC_LINE(" .--. _"),
>> + PANIC_LINE(" |o_o | | |"),
>> + PANIC_LINE(" |:_/ | | |"),
>> + PANIC_LINE(" // \\ \\ |_|"),
>> + PANIC_LINE(" (| | ) _"),
>> + PANIC_LINE(" /'\\_ _/`\\ (_)"),
>> + PANIC_LINE(" \\___)=(___/"),
>> +};
>> +
>> +static void drm_panic_fill32(struct iosys_map *map, unsigned int pitch,
>> + unsigned int height, unsigned int width,
>> + u32 color)
>> +{
>> + unsigned int y, x;
>> +
>> + for (y = 0; y < height; y++)
>> + for (x = 0; x < width; x++)
>> + iosys_map_wr(map, y * pitch + x * sizeof(u32), u32, color);
>> +}
>> +
>> +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 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);
>> + }
>> + }
>> +}
>> +
>> +static const u8 *get_char_bitmap(const struct font_desc *font, char c, size_t font_pitch)
>> +{
>> + return font->data + (c * font->height) * font_pitch;
>> +}
>> +
>> +static unsigned int get_max_line_len(const struct drm_panic_line *lines, int len)
>> +{
>> + int i;
>> + unsigned int max = 0;
>> +
>> + for (i = 0; i < len; i++)
>> + max = max(lines[i].len, max);
>> + return max;
>> +}
>> +/*
>> + * Draw a text in a rectangle on a framebuffer. The text is truncated if it overflows the rectangle
>> + */
>> +static void draw_txt_rectangle(struct drm_scanout_buffer *sb,
>> + const struct font_desc *font,
>> + const struct drm_panic_line *msg,
>> + unsigned int msg_lines,
>> + bool centered,
>> + struct drm_rect *clip,
>> + u32 fg_color,
>> + u32 bg_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;
>> +
>> + 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);
>> +
>> + if (centered)
>> + left = (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_blit32(&dst, sb->pitch[0], src, font_pitch,
>> + font->height, font->width,
>> + fg_color, bg_color);
>> + iosys_map_incr(&dst, font->width * px_width);
>> + }
>> + }
>> +}
>> +
>> +/*
>> + * Draw the panic message at the center of the screen
>> + */
>> +static void draw_panic_static(struct drm_scanout_buffer *sb)
>> +{
>> + 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;
>> + const struct font_desc *font = get_default_font(sb->width, sb->height, NULL, NULL);
>> + struct drm_rect r_logo, r_msg;
>> +
>> + if (!font)
>> + return;
>> +
>> + 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));
>> +
>> + /* 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_fill32(&sb->map[0], sb->pitch[0], sb->height, sb->width, bg_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_txt_rectangle(sb, font, panic_msg, msg_lines, true, &r_msg, fg_color, bg_color);
>> +}
>> +
>> +/*
>> + * drm_panic_is_format_supported()
>> + * @format: a fourcc color code
>> + * Returns: true if supported, false otherwise.
>> + *
>> + * Check if drm_panic will be able to use this color format.
>> + */
>> +static bool drm_panic_is_format_supported(const struct drm_format_info *format)
>> +{
>> + if (format->num_planes != 1)
>> + return false;
>> + return format->format == DRM_FORMAT_XRGB8888;
>> +}
>> +
>> +static void draw_panic_plane(struct drm_plane *plane)
>> +{
>> + struct drm_scanout_buffer sb;
>> + int ret;
>> + unsigned long flags;
>> +
>> + if (!drm_panic_trylock(plane->dev, flags))
>> + return;
>> +
>> + ret = plane->helper_private->get_scanout_buffer(plane, &sb);
>> +
>> + if (!ret && drm_panic_is_format_supported(sb.format)) {
>> + draw_panic_static(&sb);
>> + if (plane->helper_private->panic_flush)
>> + plane->helper_private->panic_flush(plane);
>> + }
>> + drm_panic_unlock(plane->dev, flags);
>> +}
>> +
>> +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)
>> +{
>> + struct drm_plane *plane = to_drm_plane(dumper);
>> +
>> + if (reason == KMSG_DUMP_PANIC)
>> + draw_panic_plane(plane);
>> +}
>> +
>> +/**
>> + * drm_panic_register() - Initialize DRM panic for a device
>> + * @dev: the drm device on which the panic screen will be displayed.
>> + */
>> +void drm_panic_register(struct drm_device *dev)
>> +{
>> + struct drm_plane *plane;
>> + int registered_plane = 0;
>> +
>> + if (!dev->mode_config.num_total_plane)
>> + return;
>> +
>> + drm_for_each_plane(plane, dev) {
>> + if (!plane->helper_private || !plane->helper_private->get_scanout_buffer)
>> + continue;
>> + plane->kmsg_panic.dump = drm_panic;
>> + plane->kmsg_panic.max_reason = KMSG_DUMP_PANIC;
>> + if (kmsg_dump_register(&plane->kmsg_panic))
>> + drm_warn(dev, "Failed to register panic handler\n");
>> + else
>> + registered_plane++;
>> + }
>> + if (registered_plane)
>> + drm_info(dev, "Registered %d planes with drm panic\n", registered_plane);
>> +}
>> +EXPORT_SYMBOL(drm_panic_register);
>> +
>> +/**
>> + * drm_panic_unregister()
>> + * @dev: the drm device previously registered.
>> + */
>> +void drm_panic_unregister(struct drm_device *dev)
>> +{
>> + struct drm_plane *plane;
>> +
>> + if (!dev->mode_config.num_total_plane)
>> + return;
>> +
>> + drm_for_each_plane(plane, dev) {
>> + if (!plane->helper_private || !plane->helper_private->get_scanout_buffer)
>> + continue;
>> + kmsg_dump_unregister(&plane->kmsg_panic);
>> + }
>> +}
>> +EXPORT_SYMBOL(drm_panic_unregister);
>> diff --git a/include/drm/drm_modeset_helper_vtables.h b/include/drm/drm_modeset_helper_vtables.h
>> index 9ed42469540e..5470ba1ced00 100644
>> --- a/include/drm/drm_modeset_helper_vtables.h
>> +++ b/include/drm/drm_modeset_helper_vtables.h
>> @@ -48,6 +48,7 @@
>> * To make this clear all the helper vtables are pulled together in this location here.
>> */
>>
>> +struct drm_scanout_buffer;
>> struct drm_writeback_connector;
>> struct drm_writeback_job;
>>
>> @@ -1443,6 +1444,42 @@ struct drm_plane_helper_funcs {
>> */
>> void (*atomic_async_update)(struct drm_plane *plane,
>> struct drm_atomic_state *state);
>> +
>> + /**
>> + * @get_scanout_buffer:
>> + *
>> + * Get the current scanout buffer, to display a message with drm_panic.
>> + * The driver should do the minimum changes to provide a linear buffer,
>> + * that can be used to display the panic screen.
>
> I'd change this to note that currently only linear buffers are supported,
> and supporting tiled formats or other more special formats is a todo item
> when we get around to adding support for that.
Yes, I agree, we want to support non-linear format in the future.
>
>> + * The device dev->mode_config.panic_lock is taken before calling this
>> + * function, so you can safely access the plane->state
> &drm_mode_config.panic_lock and &drm_plane.state for nice
> links.
>
>> + * It is called from a panic callback, and must follow its restrictions.
>> + * (no locks, no memory allocation, no sleep, no thread/workqueue, ...)
>
> Maybe instead of just "it's restrictions" add "Please look the
> documentation at drm_panic_trylock() for an in-depth discussions of what's
> safe and what is not allowed."Done
>
>> + * It's a best effort mode, so it's expected that in some complex cases
>> + * the panic screen won't be displayed.
>> + * The returned scanout_buffer->map must be valid if no error code is
>
> &drm_scanout_buffer.map so it's a nice link
> please.
>
Sure, I fixed a bunch of links in this documentation.
>> + * returned.
>> + *
>> + * Returns:
>> + *
>> + * Zero on success, negative errno on failure.
>> + */
>> + int (*get_scanout_buffer)(struct drm_plane *plane,
>> + struct drm_scanout_buffer *sb);
>> +
>> + /**
>> + * @panic_flush:
>> + *
>> + * It is used by drm_panic, and is called after the panic screen is
>> + * drawn to the scanout buffer. In this function, the driver
>> + * can send additional commands to the hardware, to make the scanout
>> + * buffer visible.
>> + * The device dev->mode_config.panic_lock is taken before calling this
>> + * function, so you can safely access the plane->state
>> + * It is called from a panic callback, and must follow its restrictions.
>> + * (no locks, no memory allocation, no sleep, no thread/workqueue, ...)
>
> I'd add here that this is only called when @get_scanout_buffer has
> returned successfully, and it's all done while holding
> &drm_mode_config.panic_lock for the entire sequence.
Done too.
>> + */
>> + void (*panic_flush)(struct drm_plane *plane);
>> };
>>
>> /**
>> diff --git a/include/drm/drm_panic.h b/include/drm/drm_panic.h
>> index 68f57710d2d1..2a2346cd0040 100644
>> --- a/include/drm/drm_panic.h
>> +++ b/include/drm/drm_panic.h
>> @@ -2,11 +2,56 @@
>> #ifndef __DRM_PANIC_H__
>> #define __DRM_PANIC_H__
>>
>> +#include <linux/module.h>
>> +#include <linux/types.h>
>> +#include <linux/iosys-map.h>
>> +
>> #include <drm/drm_device.h>
>> +#include <drm/drm_fourcc.h>
>> /*
>> * Copyright (c) 2024 Intel
>> */
>>
>> +/**
>> + * struct drm_scanout_buffer - DRM scanout buffer
>> + *
>> + * This structure holds the information necessary for drm_panic to draw the
>> + * panic screen, and display it.
>> + */
>> +struct drm_scanout_buffer {
>> + /**
>> + * @format:
>> + *
>> + * drm format of the scanout buffer.
>> + */
>> + const struct drm_format_info *format;
>> +
>> + /**
>> + * @map:
>> + *
>> + * Virtual address of the scanout buffer, either in memory or iomem.
>> + * The scanout buffer should be in linear format, and can be directly
>> + * sent to the display hardware. Tearing is not an issue for the panic
>> + * screen.
>> + */
>> + struct iosys_map map[DRM_FORMAT_MAX_PLANES];
>> +
>> + /**
>> + * @width: Width of the scanout buffer, in pixels.
>> + */
>> + unsigned int width;
>> +
>> + /**
>> + * @height: Height of the scanout buffer, in pixels.
>> + */
>> + unsigned int height;
>> +
>> + /**
>> + * @pitch: Length in bytes between the start of two consecutive lines.
>> + */
>> + unsigned int pitch[DRM_FORMAT_MAX_PLANES];
>> +};
>> +
>> /**
>> * drm_panic_trylock - try to enter the panic printing critical section
>> * @dev: struct drm_device
>> @@ -97,4 +142,16 @@
>> #define drm_panic_unlock(dev, flags) \
>> raw_spin_unlock_irqrestore(&dev->mode_config.panic_lock, flags)
>>
>> +#ifdef CONFIG_DRM_PANIC
>> +
>> +void drm_panic_register(struct drm_device *dev);
>> +void drm_panic_unregister(struct drm_device *dev);
>> +
>> +#else
>> +
>> +static inline void drm_panic_register(struct drm_device *dev) {}
>> +static inline void drm_panic_unregister(struct drm_device *dev) {}
>> +
>> +#endif
>> +
>> #endif /* __DRM_PANIC_H__ */
>> diff --git a/include/drm/drm_plane.h b/include/drm/drm_plane.h
>> index 641fe298052d..b9a2fc0a820d 100644
>> --- a/include/drm/drm_plane.h
>> +++ b/include/drm/drm_plane.h
>> @@ -25,6 +25,7 @@
>>
>> #include <linux/list.h>
>> #include <linux/ctype.h>
>> +#include <linux/kmsg_dump.h>
>> #include <drm/drm_mode_object.h>
>> #include <drm/drm_color_mgmt.h>
>> #include <drm/drm_rect.h>
>> @@ -779,6 +780,11 @@ struct drm_plane {
>> * @hotspot_y_property: property to set mouse hotspot y offset.
>> */
>> struct drm_property *hotspot_y_property;
>> +
>> + /**
>> + * @kmsg_panic: Used to register a panic notifier for this plane
>> + */
>> + struct kmsg_dumper kmsg_panic;
>> };
>>
>> #define obj_to_plane(x) container_of(x, struct drm_plane, base)
>> --
>> 2.44.0
>>
>
Best regards,
--
Jocelyn
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