[PATCH v11 0/9] drm/panic: Add a drm panic handler

[Thomas Zimmermann]

Hi,

for patches 6, 7, and 9

Reviewed-by: Thomas Zimmermann <tzimmermann at suse.de>

Best regards
Thomas

Am 28.03.24 um 13:03 schrieb Jocelyn Falempe:
> This introduces a new drm panic handler, which displays a message when a panic occurs.
> So when fbcon is disabled, you can still see a kernel panic.
>
> This is one of the missing feature, when disabling VT/fbcon in the kernel:
> https://www.reddit.com/r/linux/comments/10eccv9/config_vtn_in_2023/
> Fbcon can be replaced by a userspace kms console, but the panic screen must be done in the kernel.
>
> It works with simpledrm, mgag200, ast, and imx.
>
> To test it, make sure you're using one of the supported driver, and trigger a panic:
> echo c > /proc/sysrq-trigger
>
> or you can enable CONFIG_DRM_PANIC_DEBUG and echo 1 > /sys/kernel/debug/dri/0/drm_panic_plane_0
>
> There were not many comments on v10, so I think we're close to something that can be merged.
> Even if this is not yet useful, it will allows to work on more driver support, and
> better debug information.
>
> 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:
>   * Fully support all simpledrm formats using drm conversion helpers
>   * Rename dpanic_* to drm_panic_*, and have more coherent function name.
>     (Thomas Zimmermann)
>   * 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 driver to drm_panic, if the function
>     get_scanout_buffer() exists. (Thomas Zimmermann)
>   * Add mgag200 support.
>   
> v5:
>   * Change the drawing API, use drm_fb_blit_from_r1() to draw the font.
>     (Thomas Zimmermann)
>   * 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().
>   * Add ast support.
>   * Add experimental imx/ipuv3 support, to test on an ARM hw. (Maxime Ripard)
>
> v6:
>   * Fix sparse and __le32 warnings
>   * Drop the IMX/IPUV3 experiment, it was just to show that it works also on
>     ARM devices.
>
> v7:
>   * Add a check to see if the 4cc format is supported by drm_panic.
>   * Add a drm/plane helper to loop over all visible primary buffer,
>     simplifying the get_scanout_buffer implementations
>   * Add a generic implementation for drivers that uses drm_fb_dma. (Maxime Ripard)
>   * Add back the IMX/IPUV3 support, and use the generic implementation. (Maxime Ripard)
>
> v8:
>   * Directly register each plane to the panic notifier (Sima)
>   * Replace get_scanout_buffer() with set_scanout_buffer() to simplify
>     the locking. (Thomas Zimmermann)
>   * Add a debugfs entry, to trigger the drm_panic without a real panic (Sima)
>   * Fix the drm_panic Documentation, and include it in drm-kms.rst
>
> 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)
>   * Create a debugfs file for each plane in the device's debugfs
>     directory. This allows to test for each plane of each GPU
>     independently.
> 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).
>   * Use spinlock_irqsave/restore (John Ogness)
>
> v11:
>   * Use macro instead of inline functions for drm_panic_lock/unlock (John Ogness)
>
>
> Best regards,
>
> Daniel Vetter (1):
>    drm/panic: Add drm panic locking
>
> Jocelyn Falempe (8):
>    drm/panic: Add a drm panic handler
>    drm/panic: Add support for color format conversion
>    drm/panic: Add debugfs entry to test without triggering panic.
>    drm/fb_dma: Add generic get_scanout_buffer() for drm_panic
>    drm/simpledrm: Add drm_panic support
>    drm/mgag200: Add drm_panic support
>    drm/imx: Add drm_panic support
>    drm/ast: Add drm_panic support
>
>   Documentation/gpu/drm-kms.rst            |  12 +
>   drivers/gpu/drm/Kconfig                  |  32 ++
>   drivers/gpu/drm/Makefile                 |   1 +
>   drivers/gpu/drm/ast/ast_mode.c           |  18 +
>   drivers/gpu/drm/drm_atomic_helper.c      |   4 +
>   drivers/gpu/drm/drm_drv.c                |   5 +
>   drivers/gpu/drm/drm_fb_dma_helper.c      |  47 ++
>   drivers/gpu/drm/drm_panic.c              | 581 +++++++++++++++++++++++
>   drivers/gpu/drm/imx/ipuv3/ipuv3-plane.c  |  11 +-
>   drivers/gpu/drm/mgag200/mgag200_drv.h    |   7 +-
>   drivers/gpu/drm/mgag200/mgag200_mode.c   |  18 +
>   drivers/gpu/drm/tiny/simpledrm.c         |  16 +
>   include/drm/drm_fb_dma_helper.h          |   4 +
>   include/drm/drm_mode_config.h            |  10 +
>   include/drm/drm_modeset_helper_vtables.h |  37 ++
>   include/drm/drm_panic.h                  | 152 ++++++
>   include/drm/drm_plane.h                  |   6 +
>   17 files changed, 959 insertions(+), 2 deletions(-)
>   create mode 100644 drivers/gpu/drm/drm_panic.c
>   create mode 100644 include/drm/drm_panic.h
>
>
> base-commit: 6376eb8b911534735fec104c1a0d780e4cf3116a

-- 
--
Thomas Zimmermann
Graphics Driver Developer
SUSE Software Solutions Germany GmbH
Frankenstrasse 146, 90461 Nuernberg, Germany
GF: Ivo Totev, Andrew Myers, Andrew McDonald, Boudien Moerman
HRB 36809 (AG Nuernberg)