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

[Simona Vetter <simona.vetter@ffwll.ch>]

On Thu, Mar 13, 2025 at 04:51:51PM +0000, Lee Jones wrote:
> 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 looked throught the series and it's a small step, but I think it's the
right direction for where we want backlight/fbdev/drm-kms to head towards
long-term. So on the series:

Acked-by: Simona Vetter <simona.vetter@ffwll.ch>

Cheers, Sima

> 
> -- 
> Lee Jones [李琼斯]

-- 
Simona Vetter
Software Engineer, Intel Corporation
http://blog.ffwll.ch