Messages in this thread | | | Subject | Re: Re: [PATCH v3 2/4] backlight: Expose brightness curve type through sysfs | From | Daniel Thompson <> | Date | Fri, 16 Aug 2019 16:54:18 +0100 |
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On 07/08/2019 21:15, Matthias Kaehlcke wrote: > On Tue, Jul 09, 2019 at 12:00:05PM -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 currently is opaque >> to userspace, so userspace often uses 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 the new sysfs attribute >> 'scale'. The value of the attribute can be 'linear', 'non-linear' or >> 'unknown'. For devices that don't provide information about the scale >> of their brightness curve the value of the 'scale' attribute is 'unknown'. >> >> Signed-off-by: Matthias Kaehlcke <mka@chromium.org> > > Daniel (et al): do you have any more comments on this patch/series or > is it ready to land?
I decided to leave it for a long while for others to review since I'm still a tiny bit uneasy about the linear/non-linear terminology.
However that's my only concern, its fairly minor and I've dragged by feet for more then long enough, so: Reviewed-by: Daniel Thompson <daniel.thompson@linaro.org>
Daniel.
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