bf9fb17c66
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@redhat.com> Link: https://patchwork.freedesktop.org/patch/msgid/20240409163432.352518-3-jfalempe@redhat.com Acked-by: Daniel Vetter <daniel.vetter@ffwll.ch>
153 lines
5.0 KiB
C
153 lines
5.0 KiB
C
/* SPDX-License-Identifier: GPL-2.0 or MIT */
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#ifndef __DRM_PANIC_H__
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#define __DRM_PANIC_H__
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#include <linux/module.h>
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#include <linux/types.h>
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#include <linux/iosys-map.h>
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#include <drm/drm_device.h>
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#include <drm/drm_fourcc.h>
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/*
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* Copyright (c) 2024 Intel
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*/
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/**
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* struct drm_scanout_buffer - DRM scanout buffer
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*
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* This structure holds the information necessary for drm_panic to draw the
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* panic screen, and display it.
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*/
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struct drm_scanout_buffer {
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/**
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* @format:
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*
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* drm format of the scanout buffer.
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*/
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const struct drm_format_info *format;
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/**
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* @map:
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*
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* Virtual address of the scanout buffer, either in memory or iomem.
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* The scanout buffer should be in linear format, and can be directly
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* sent to the display hardware. Tearing is not an issue for the panic
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* screen.
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*/
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struct iosys_map map[DRM_FORMAT_MAX_PLANES];
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/**
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* @width: Width of the scanout buffer, in pixels.
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*/
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unsigned int width;
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/**
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* @height: Height of the scanout buffer, in pixels.
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*/
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unsigned int height;
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/**
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* @pitch: Length in bytes between the start of two consecutive lines.
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*/
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unsigned int pitch[DRM_FORMAT_MAX_PLANES];
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};
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/**
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* drm_panic_trylock - try to enter the panic printing critical section
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* @dev: struct drm_device
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* @flags: unsigned long irq flags you need to pass to the unlock() counterpart
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*
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* This function must be called by any panic printing code. The panic printing
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* attempt must be aborted if the trylock fails.
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*
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* Panic printing code can make the following assumptions while holding the
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* panic lock:
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*
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* - Anything protected by drm_panic_lock() and drm_panic_unlock() pairs is safe
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* to access.
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*
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* - Furthermore the panic printing code only registers in drm_dev_unregister()
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* and gets removed in drm_dev_unregister(). This allows the panic code to
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* safely access any state which is invariant in between these two function
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* calls, like the list of planes &drm_mode_config.plane_list or most of the
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* struct drm_plane structure.
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*
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* Specifically thanks to the protection around plane updates in
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* drm_atomic_helper_swap_state() the following additional guarantees hold:
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*
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* - It is safe to deference the drm_plane.state pointer.
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*
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* - Anything in struct drm_plane_state or the driver's subclass thereof which
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* stays invariant after the atomic check code has finished is safe to access.
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* Specifically this includes the reference counted pointers to framebuffer
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* and buffer objects.
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*
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* - Anything set up by &drm_plane_helper_funcs.fb_prepare and cleaned up
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* &drm_plane_helper_funcs.fb_cleanup is safe to access, as long as it stays
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* invariant between these two calls. This also means that for drivers using
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* dynamic buffer management the framebuffer is pinned, and therefer all
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* relevant datastructures can be accessed without taking any further locks
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* (which would be impossible in panic context anyway).
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*
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* - Importantly, software and hardware state set up by
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* &drm_plane_helper_funcs.begin_fb_access and
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* &drm_plane_helper_funcs.end_fb_access is not safe to access.
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*
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* Drivers must not make any assumptions about the actual state of the hardware,
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* unless they explicitly protected these hardware access with drm_panic_lock()
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* and drm_panic_unlock().
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*
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* Return:
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* %0 when failing to acquire the raw spinlock, nonzero on success.
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*/
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#define drm_panic_trylock(dev, flags) \
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raw_spin_trylock_irqsave(&(dev)->mode_config.panic_lock, flags)
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/**
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* drm_panic_lock - protect panic printing relevant state
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* @dev: struct drm_device
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* @flags: unsigned long irq flags you need to pass to the unlock() counterpart
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*
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* This function must be called to protect software and hardware state that the
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* panic printing code must be able to rely on. The protected sections must be
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* as small as possible. It uses the irqsave/irqrestore variant, and can be
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* called from irq handler. Examples include:
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*
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* - Access to peek/poke or other similar registers, if that is the way the
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* driver prints the pixels into the scanout buffer at panic time.
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*
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* - Updates to pointers like &drm_plane.state, allowing the panic handler to
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* safely deference these. This is done in drm_atomic_helper_swap_state().
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*
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* - An state that isn't invariant and that the driver must be able to access
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* during panic printing.
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*/
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#define drm_panic_lock(dev, flags) \
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raw_spin_lock_irqsave(&(dev)->mode_config.panic_lock, flags)
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/**
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* drm_panic_unlock - end of the panic printing critical section
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* @dev: struct drm_device
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* @flags: irq flags that were returned when acquiring the lock
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*
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* Unlocks the raw spinlock acquired by either drm_panic_lock() or
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* drm_panic_trylock().
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*/
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#define drm_panic_unlock(dev, flags) \
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raw_spin_unlock_irqrestore(&(dev)->mode_config.panic_lock, flags)
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#ifdef CONFIG_DRM_PANIC
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void drm_panic_register(struct drm_device *dev);
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void drm_panic_unregister(struct drm_device *dev);
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#else
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static inline void drm_panic_register(struct drm_device *dev) {}
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static inline void drm_panic_unregister(struct drm_device *dev) {}
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#endif
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#endif /* __DRM_PANIC_H__ */
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