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

[Daniel Thompson]

On Mon, Mar 17, 2025 at 09:42:11AM +0100, Thomas Zimmermann wrote:
> Hi
>
> Am 13.03.25 um 17:51 schrieb 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.
>
> I'm confused. Are you not the backlight maintainer?

Lee is, yes, but this kind of comment is usually a hint that I've
been delinquent in my backlight reviews and records that he hasn't
looked at the backlight code yet ;-).

I'll get on it tomorrow!


Daniel.