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SubjectRe: [PATCH v3 0/4] backlight: Expose brightness curve type through sysfs
On Tue, Jul 09, 2019 at 12:00:03PM -0700, Matthias Kaehlcke wrote:
> Backlight brightness curves can have different shapes. The two main
> types are linear and non-linear curves. The human eye doesn't
> perceive linearly increasing/decreasing brightness as linear (see
> also 88ba95bedb79 "backlight: pwm_bl: Compute brightness of LED
> linearly to human eye"), hence many backlights use non-linear (often
> logarithmic) brightness curves. The type of curve is currently opaque
> to userspace, so userspace often relies on more or less reliable
> heuristics (like the number of brightness levels) to decide whether
> to treat a backlight device as linear or non-linear.
>
> Export the type of the brightness curve via a new sysfs attribute.
>
> Matthias Kaehlcke (4):
> MAINTAINERS: Add entry for stable backlight sysfs ABI documentation
> backlight: Expose brightness curve type through sysfs
> backlight: pwm_bl: Set scale type for CIE 1931 curves
> backlight: pwm_bl: Set scale type for brightness curves specified in
> the DT
>
> .../ABI/testing/sysfs-class-backlight | 26 ++++++++++++++
> MAINTAINERS | 2 ++
> drivers/video/backlight/backlight.c | 19 ++++++++++
> drivers/video/backlight/pwm_bl.c | 35 ++++++++++++++++++-
> include/linux/backlight.h | 8 +++++
> 5 files changed, 89 insertions(+), 1 deletion(-)
> create mode 100644 Documentation/ABI/testing/sysfs-class-backlight

ping, any comments on v3?

Thanks

Matthias

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