On Mon, Jul 20, 2020 at 9:27 PM Alexandru Stan <amstan@xxxxxxxxxxxx> wrote: > > I was trying to adjust the brightness for a new chromebook: > https://chromium-review.googlesource.com/c/chromiumos/third_party/kernel/+/2291209 > Like a lot of panels, the low end needs to be cropped, > and now that we have the interpolation stuff I wanted to make use of it > and bake in even the curve. > > I found the behavior a little unintuitive and non-linear. See patch 1 > for a suggested fix for this. > > Unfortunatelly a few veyron dts files were relying on this > (perhaps weird) behavior. Those devices also want a minimum brightness. > The issue is that they also want the 0% point for turning off the > display. > https://github.com/torvalds/linux/commit/6233269bce47bd450196a671ab28eb1ec5eb88d9#diff-e401ae20091bbfb311a062c464f4f47fL23 > > So the idea here is to change those dts files to only say <3 255> (patch > 3), and add in a virtual 0% point at the bottom of the scale (patch 2). > > We have to do this conditionally because it seems some devices like to > have the scale inverted: > % git grep "brightness-levels\s*=\s*<\s*[1-9]"|cat > arch/arm/boot/dts/tegra124-apalis-eval.dts: brightness-levels = <255 231 223 207 191 159 127 0>; > > > Alexandru Stan (3): > backlight: pwm_bl: Fix interpolation > backlight: pwm_bl: Artificially add 0% during interpolation > ARM: dts: rockchip: Remove 0 point in backlight > > arch/arm/boot/dts/rk3288-veyron-jaq.dts | 2 +- > arch/arm/boot/dts/rk3288-veyron-minnie.dts | 2 +- > arch/arm/boot/dts/rk3288-veyron-tiger.dts | 2 +- > drivers/video/backlight/pwm_bl.c | 78 +++++++++++----------- > 4 files changed, 42 insertions(+), 42 deletions(-) > > -- > 2.27.0 > Hello, Friendly ping. Let me know if you would like me to make any changes to my patches. Thanks, Alexandru M Stan
