[PATCH v3 00/11] backlight, lcd, led: Remove fbdev dependencies

[Lee Jones]

On Thu, 06 Mar 2025, Thomas Zimmermann wrote:

> This series removes the remaining 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 and 8 remove fbdev event handling from lcd code and patches 9 and 10
> 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 test this
> series.
> 
> v3:
> - export several symbols
> - static-inline declare empty placeholders
> v2:
> - avoid IS_REACHABLE() in source file (Lee)
> - simplify several interfaces and helpers
> - use lock guards
> - initialize global lists and mutices
> 
> Thomas Zimmermann (11):
>   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: Move event handling into helpers
>   backlight: lcd: Replace fb events with a dedicated function call
>   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 |  48 +++++-----
>  drivers/video/backlight/backlight.c      |  93 +++++--------------
>  drivers/video/backlight/lcd.c            | 108 +++++++++--------------
>  drivers/video/fbdev/core/fb_backlight.c  |  12 +++
>  drivers/video/fbdev/core/fb_info.c       |   1 +
>  drivers/video/fbdev/core/fbmem.c         |  82 ++++++++++++++---
>  drivers/video/fbdev/core/fbsysfs.c       |   8 +-
>  include/linux/backlight.h                |  22 ++---
>  include/linux/fb.h                       |  12 +--
>  include/linux/lcd.h                      |  21 ++++-
>  include/linux/leds.h                     |   6 ++
>  11 files changed, 205 insertions(+), 208 deletions(-)

No immediately obvious issues from the LEDs side.

Still needs reviews from Backlight and fbdev.

-- 
Lee Jones [李琼斯]