Update VR HAL docs.
Bug: 28526281
Change-Id: If9673af47962f6fadd10f8a622e9587245f7ffb6
diff --git a/include/hardware/lights.h b/include/hardware/lights.h
index b426caf..b3d28b0 100644
--- a/include/hardware/lights.h
+++ b/include/hardware/lights.h
@@ -110,15 +110,20 @@
* 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
- * overriden by the HAL implementation.
+ * overridden by the HAL implementation.
*
- * For an optimal HMD viewing experience, the display should meet the following
+ * For an optimal HMD viewing experience, the display must meet the following
* criteria in this mode:
- * - Less than 2ms display persistence.
+ * - 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