On 17/12/2024 15:19, Geert Uytterhoeven wrote:
Hi Jocelyn,
On Wed, Dec 4, 2024 at 6:41 PM Jocelyn Falempe <jfale...@redhat.com> wrote:
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.
If you're curious on how it looks like, I've put a small demo here:
https://people.redhat.com/jfalempe/drm_log/drm_log_draft_boot_v2.mp4
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
I gave this a try on Koelsch (R-Car M2-W), using rcar-du.
Unfortunately I don't see any kernel messages, and my monitor complains
about no signal. Does this require special support from the driver?
It doesn't require a special support from the driver. But as it is the
first drm client other than fbdev emulation, I'm not surprised it's
broken on some driver.
I know it works on virtio-gpu, nouveau, amdgpu, and even on a OnePlus 6
(Qualcomm SDM845/freedreno), without requiring driver changes.
Do you have a serial console on this device, to check if there is
something in kmsg?
Best regards,
--
Jocelyn
CONFIG_DRM_CLIENT=y
CONFIG_DRM_CLIENT_LIB=y
CONFIG_DRM_CLIENT_SELECTION=y
CONFIG_DRM_CLIENT_SETUP=y
CONFIG_DRM_CLIENT_LOG=y
# CONFIG_DRM_CLIENT_DEFAULT_FBDEV is not set
CONFIG_DRM_CLIENT_DEFAULT_LOG=y
CONFIG_DRM_CLIENT_DEFAULT="log"
Switching to fbdev gives a working display, as before:
CONFIG_DRM_CLIENT_DEFAULT_FBDEV=y
# CONFIG_DRM_CLIENT_DEFAULT_LOG is not set
CONFIG_DRM_CLIENT_DEFAULT="fbdev"
Thanks!
Gr{oetje,eeting}s,
Geert
