* "DEGAMMA_LUT”:
* Blob property to set the degamma lookup table (LUT) mapping pixel data
* from the framebuffer before it is given to the transformation matrix.
- * The data is interpreted as an array of struct &drm_color_lut elements.
+ * The data is interpreted as an array of &struct drm_color_lut elements.
* Hardware might choose not to use the full precision of the LUT elements
* nor use all the elements of the LUT (for example the hardware might
* choose to interpolate between LUT[0] and LUT[4]).
* “GAMMA_LUT”:
* Blob property to set the gamma lookup table (LUT) mapping pixel data
* after the transformation matrix to data sent to the connector. The
- * data is interpreted as an array of struct &drm_color_lut elements.
+ * data is interpreted as an array of &struct drm_color_lut elements.
* Hardware might choose not to use the full precision of the LUT elements
* nor use all the elements of the LUT (for example the hardware might
* choose to interpolate between LUT[0] and LUT[4]).
* "GAMMA_LUT" property above.
*/
+/**
+ * drm_color_lut_extract - clamp and round LUT entries
+ * @user_input: input value
+ * @bit_precision: number of bits the hw LUT supports
+ *
+ * Extract a degamma/gamma LUT value provided by user (in the form of
+ * &drm_color_lut entries) and round it to the precision supported by the
+ * hardware.
+ */
+uint32_t drm_color_lut_extract(uint32_t user_input, uint32_t bit_precision)
+{
+ uint32_t val = user_input;
+ uint32_t max = 0xffff >> (16 - bit_precision);
+
+ /* Round only if we're not using full precision. */
+ if (bit_precision < 16) {
+ val += 1UL << (16 - bit_precision - 1);
+ val >>= 16 - bit_precision;
+ }
+
+ return clamp_val(val, 0, max);
+}
+EXPORT_SYMBOL(drm_color_lut_extract);
+
/**
* drm_crtc_enable_color_mgmt - enable color management properties
* @crtc: DRM CRTC