Re: [PATCH v3 4/4] backlight: pwm_bl: Set scale type for brightness curves specified in the DT

On Tue, 09 Jul 2019, Matthias Kaehlcke wrote:

Check if a brightness curve specified in the device tree is linear or not and set the corresponding property accordingly. This makes the scale type available to userspace via the 'scale' sysfs attribute.

To determine if a curve is linear it is compared to a interpolated linear curve between min and max brightness. The curve is considered linear if no value deviates more than +/-5% of ${brightness_range} from their interpolated value.

Signed-off-by: Matthias Kaehlcke mka@chromium.org Acked-by: Daniel Thompson daniel.thompson@linaro.org

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Changes in v3:

• none

Changes in v2:

• use 128 (power of two) instead of 100 as factor for the slope
• add comment about max quantization error
• added Daniel's 'Acked-by' tag

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drivers/video/backlight/pwm_bl.c | 30 ++++++++++++++++++++++++++++++ 1 file changed, 30 insertions(+)

Applied, thanks.