Hi! > Export the type of the brightness curve via the new sysfs attribute > 'scale'. The value of the attribute may be a simple string like > 'linear' or 'non-linear', or a composite string similar to > 'compatible' strings of the device tree. A composite string consists > of different elements separated by commas, starting with the > most-detailed description and ending with the least-detailed one. An > example for a composite string is "cie-1931,perceptual,non-linear" > This brightness curve was generated with the CIE 1931 algorithm, it > is perceptually linear, but not actually linear in terms of the > emitted light. If userspace doesn't know about 'cie-1931' or > 'perceptual' it should at least be able to interpret the 'non-linear' > part. I'm not sure the comma-separated thing is a good idea. If it is, it should go to the Documentation, not to changelog. > +What: /sys/class/backlight/<backlight>/scale > +Date: June 2019 > +KernelVersion: 5.4 > +Contact: Daniel Thompson <daniel.thompson@xxxxxxxxxx> > +Description: > + Description of the scale of the brightness curve. The > + description consists of one or more elements separated by > + commas, from the most detailed to the least detailed > + description. > + > + Possible values are: > + > + unknown > + The scale of the brightness curve is unknown. > + > + linear > + The brightness changes linearly in terms of the emitted > + light, changes are perceived as non-linear by the human eye. > + > + non-linear > + The brightness changes non-linearly in terms of the emitted > + light, changes might be perceived as linear by the human eye. non-linear is not too useful as described. > + perceptual,non-linear > + The brightness changes non-linearly in terms of the emitted > + light, changes should be perceived as linear by the human eye. > + > + cie-1931,perceptual,non-linear > + The brightness curve was calculated with the CIE 1931 > + algorithm. Brightness changes non-linearly in terms of the > + emitted light, changes should be perceived as linear by the > + human eye. Is it useful to know difference between perceptual, and cie-1931? Would it be useful to export absolute values in some well-known units? If I'm in dark room, I may want 100mW/m^2 of backlight... And it would be nice if I could set same backlight intensity on all my devices easily. Pavel _______________________________________________ dri-devel mailing list dri-devel@xxxxxxxxxxxxxxxxxxxxx https://lists.freedesktop.org/mailman/listinfo/dri-devel
