[v2,0/4] backlight: pwm_bl: optimizations and small fix for cie1913

Message

Rasmus Villemoes Oct. 8, 2019, 12:03 p.m. UTC

These patches optimize the cie1913() implementation by using fewer 64
bit divisions and multiplications. It also contains a minor fix for
the linear constant used.

v2:
- Drop patch 5.
- Fix thinko in patch 4, otherwise no code change.
- Better changelog in patch 3.
- Add Daniel's Reviewed-By to the four patches.

Daniel, I took the liberty of adding your R-B to patch 4 despite
changing it a little to fix a thinko - I should add 1<<31 and not
1<<15. Please tell me if that was inappropriate.

Rasmus Villemoes (4):
  backlight: pwm_bl: fix cie1913 comments and constant
  backlight: pwm_bl: eliminate a 64/32 division
  backlight: pwm_bl: drop use of int_pow()
  backlight: pwm_bl: switch to power-of-2 base for fixed-point math

 drivers/video/backlight/pwm_bl.c | 29 +++++++++++++++++++----------
 1 file changed, 19 insertions(+), 10 deletions(-)