[RFC,00/13] backlight, lcd, led: Remove fbdev dependencies

Message

Thomas Zimmermann Feb. 6, 2025, 3:30 p.m. UTC

This series removes the last dependencies on fbdev from the backlight,
lcd and led subsystems. Each depends on fbdev events to track display
state. Make fbdev inform each subsystem via a dedicated interface
instead.

Patches 1 to 3 make fbdev track blank state for each display, so
that backlight code doesn't have to.

Patches 4 to 6 remove fbdev event handling from backlight code. Patches
7 to 9 remove fbdev event handling from lcd code and patches 10 to 12
do the same for led's backlight trigger.

The final patch removes the event constants from fbdev.

With the series applied, the three subsystems do no longer depend
on fbdev. It's also a clean up for fbdev. Fbdev used to send out a
large number of events. That mechanism has been deprecated for some
time and converted call to dedicated functions instead.

Testing is very welcome, as I don't have the hardware to really test
this series.

Thomas Zimmermann (13):
  fbdev: Rework fb_blank()
  fbdev: Track display blanking state
  fbdev: Send old blank state in FB_EVENT_BLANK
  backlight: Implement fbdev tracking with blank state from event
  backlight: Move blank-state handling into helper
  backlight: Replace fb events with a dedicated function call
  backlight: lcd: Maintain global list of lcd devices
  backlight: lcd: Move event handling into helpers
  backlight: lcd: Replace fb events with a dedicated function call
  leds: backlight trigger: Maintain global list of led backlight
    triggers
  leds: backlight trigger: Move blank-state handling into helper
  leds: backlight trigger: Replace fb events with a dedicated function
    call
  fbdev: Remove constants of unused events

 drivers/leds/trigger/ledtrig-backlight.c |  49 +++++-----
 drivers/video/backlight/backlight.c      |  93 +++++--------------
 drivers/video/backlight/lcd.c            | 109 +++++++++--------------
 drivers/video/fbdev/core/fb_backlight.c  |  12 +++
 drivers/video/fbdev/core/fb_info.c       |   1 +
 drivers/video/fbdev/core/fbmem.c         |  88 +++++++++++++++---
 drivers/video/fbdev/core/fbsysfs.c       |   8 +-
 include/linux/backlight.h                |  22 ++---
 include/linux/fb.h                       |  12 +--
 include/linux/lcd.h                      |  12 ++-
 include/linux/leds.h                     |   6 ++
 11 files changed, 204 insertions(+), 208 deletions(-)