Use a low-persistence mode for display backlights.
When set, the device driver must switch to a mode optimized for low display persistence that is intended to be used when the device is being treated as a head mounted display (HMD). The actual display brightness in this mode is implementation dependent, and any value set for color in light_state may be overridden by the HAL implementation.
For an optimal HMD viewing experience, the display must meet the following criteria in this mode:
- Gray-to-Gray, White-to-Black, and Black-to-White switching time must be ≤ 3 ms.
- The display must support low-persistence with ≤ 3.5 ms persistence. Persistence is defined as the amount of time for which a pixel is emitting light for a single frame.
- Any "smart panel" or other frame buffering options that increase display latency are disabled.
- Display brightness is set so that the display is still visible to the user under normal indoor lighting.
- The display must update at 60 Hz at least, but higher refresh rates are recommended for low latency.
This mode will only be used with light devices of type LIGHT_ID_BACKLIGHT, and will only be called by the Android framework for light_device_t implementations that report a version >= 2.0 in their hw_device_t common fields. If the device version is >= 2.0 and this mode is unsupported, calling set_light with this mode must return the negative error code -ENOSYS (-38) without altering any settings.
Available only for version >= LIGHTS_DEVICE_API_VERSION_2_0
Definition at line 137 of file lights.h.