diff options
Diffstat (limited to 'drivers/gpu/drm/drm_color_mgmt.c')
| -rw-r--r-- | drivers/gpu/drm/drm_color_mgmt.c | 28 |
1 files changed, 26 insertions, 2 deletions
diff --git a/drivers/gpu/drm/drm_color_mgmt.c b/drivers/gpu/drm/drm_color_mgmt.c index 6543ebde501a..cc23b9a505c0 100644 --- a/drivers/gpu/drm/drm_color_mgmt.c +++ b/drivers/gpu/drm/drm_color_mgmt.c @@ -36,7 +36,7 @@ * "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]). @@ -65,7 +65,7 @@ * “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]). @@ -88,6 +88,30 @@ */ /** + * 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 * @degamma_lut_size: the size of the degamma lut (before CSC) |