On 24/02/17 08:43, Jani Nikula wrote: >> - "Some PWM based backlight allow adjusting the PWM modulation >> frequency." you don't need a motivation for *why* I would want to >> change the mod freq on the fly, actually in my experience you >> shouldn't since this can lead to flickery backlights. > > The modulation frequency is usually an OEM design choice. The higher > the > frequency, less flicker, but also fewer user distinguishable levels of > backlight (signal rise/fall times come into play). Occasionally there > have been requests to be able to adjust the frequency. We can of course > decide that's an implementation detail and not let userspace change it.
In principle the backlight max level could also change during monitor hotplug; recent versions DDC/CI include a backlight properties. We have no driver for this right now but conversation is starting (and proper backlight support in DRM connectors will probably help it happen faster).
I'm afraid I have no idea if this is "real" or now. Right now I have no clue how many monitors implement it. For regular desktop monitors which mirror old school brightness/contrast in their UI then 0 wouldn't surprise me much ;-)
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