Restore the log client's output when the DRM core invokes the restore
callback. Follow the existing behavior of fbdev emulation wrt. the
value of the force parameter.
If force is false, acquire the DRM master lock and reprogram the
display. This is the case when the user-space compositor exits and
the DRM core transfers the display back to the in-kernel client. This
also enables drm_log output during reboot and shutdown.
If force is true, reprogram without considering the master lock. This
overrides the current compositor and prints the log to the screen. In
case of system malfunction, users can enter SysRq+v to invoke the
emergency error reporting. See Documentation/admin-guide/sysrq.rst for
more information.
v2:
- s/exists/exits/ in second paragraph of commit description
- fix grammar in commit description
Signed-off-by: Thomas Zimmermann <tzimmermann@suse.de>
Reviewed-by: Jocelyn Falempe <jfalempe@redhat.com>
Link: https://patch.msgid.link/20251110154616.539328-4-tzimmermann@suse.de
Rename drm_client_framebuffer_create() to drm_client_buffer_create_dump()
and adapt callers. The new name reflects the function's purpose. Using
dumb buffers is the easiest way for creating a GEM buffer in a drivers-
independent way.
There's also drm_client_buffer_create(), which creates the client buffer
from a preexisting buffer object. This helper can be exported for drivers
that create their own GEM buffer object.
Signed-off-by: Thomas Zimmermann <tzimmermann@suse.de>
Reviewed-by: Jocelyn Falempe <jfalempe@redhat.com>
Tested-by: Francesco Valla <francesco@valla.it>
Link: https://patch.msgid.link/20251027121042.143588-7-tzimmermann@suse.de
Release client buffers with drm_client_buffer_delete() instead of
drm_client_framebuffer_delete(). The latter is just a tiny wrapper
around the former.
Move the test for !buffer into drm_client_buffer_delete(), although
all callers appear to always have a valid pointer.
v2:
- test for !buffer before deref-ing pointer (Jocelyn, Dan)
Signed-off-by: Thomas Zimmermann <tzimmermann@suse.de>
Reviewed-by: Jocelyn Falempe <jfalempe@redhat.com>
Tested-by: Francesco Valla <francesco@valla.it>
Link: https://patch.msgid.link/20251027121042.143588-6-tzimmermann@suse.de
When calling drm_client_release(), the client is already quiescent.
Internal locks should therefore be dropped before the caller releases
the client.
In the case of the DRM log, concurrency originates from the console or
from client events. The console has been unregistered in the previous
line. The caller of the unregister callback, drm_log_client_unregister(),
holds clientlist_mutex from struct drm_device to protect against concurrent
client events. It is therefore safe to release the client without holding
locks.
Signed-off-by: Thomas Zimmermann <tzimmermann@suse.de>
Reviewed-by: Jocelyn Falempe <jfalempe@redhat.com>>
Link: https://lore.kernel.org/r/20251009132006.45834-3-tzimmermann@suse.de
drm_log is a simple logger that uses the drm_client API to print the
kmsg boot log on the screen. This is not a full replacement to fbcon,
as it will only print the kmsg. It will never handle user input, or a
terminal because this is better done in userspace.
Design decisions:
* It uses the drm_client API, so it should work on all drm drivers
from the start.
* It doesn't scroll the message, that way it doesn't need to redraw
the whole screen for each new message.
It also means it doesn't have to keep drawn messages in memory, to
redraw them when scrolling.
* It uses the new non-blocking console API, so it should work well
with PREEMPT_RT.
This patch also adds a Kconfig menu to select the drm client to use.
It can be overwritten on the kernel command line with:
drm_client_lib.active=log or drm_client_lib.active=fbdev
Signed-off-by: Jocelyn Falempe <jfalempe@redhat.com>
Reviewed-by: John Ogness <john.ogness@linutronix.de> # console API
Reviewed-by: Thomas Zimmermann <tzimmermann@suse.de>
Link: https://patchwork.freedesktop.org/patch/msgid/20241204160014.1171469-3-jfalempe@redhat.com
