From: Anthony Koo Date: Wed, 30 Jan 2019 16:05:38 +0000 (-0500) Subject: drm/amd/display: Increase precision for backlight curve X-Git-Tag: v5.15~6763^2~10^2~16 X-Git-Url: http://review.tizen.org/git/?a=commitdiff_plain;h=c19bd82f8b33f6cf505df0ff5027d4679fedaa3e;p=platform%2Fkernel%2Flinux-starfive.git drm/amd/display: Increase precision for backlight curve [Why] We are currently losing precision when we convert from 16 bit --> 8 bit --> 16 bit. [How] We shouldn't down convert unnecessarily and lose precision. Keep values at 16 bit and use directly. Signed-off-by: Anthony Koo Reviewed-by: Aric Cyr Acked-by: Leo Li Signed-off-by: Alex Deucher --- diff --git a/drivers/gpu/drm/amd/display/modules/power/power_helpers.c b/drivers/gpu/drm/amd/display/modules/power/power_helpers.c index 3ba87b0..038b882 100644 --- a/drivers/gpu/drm/amd/display/modules/power/power_helpers.c +++ b/drivers/gpu/drm/amd/display/modules/power/power_helpers.c @@ -165,18 +165,11 @@ struct iram_table_v_2_2 { }; #pragma pack(pop) -static uint16_t backlight_8_to_16(unsigned int backlight_8bit) -{ - return (uint16_t)(backlight_8bit * 0x101); -} - static void fill_backlight_transform_table(struct dmcu_iram_parameters params, struct iram_table_v_2 *table) { unsigned int i; unsigned int num_entries = NUM_BL_CURVE_SEGS; - unsigned int query_input_8bit; - unsigned int query_output_8bit; unsigned int lut_index; table->backlight_thresholds[0] = 0; @@ -194,16 +187,13 @@ static void fill_backlight_transform_table(struct dmcu_iram_parameters params, * format U4.10. */ for (i = 1; i+1 < num_entries; i++) { - query_input_8bit = DIV_ROUNDUP((i * 256), num_entries); - lut_index = (params.backlight_lut_array_size - 1) * i / (num_entries - 1); ASSERT(lut_index < params.backlight_lut_array_size); - query_output_8bit = params.backlight_lut_array[lut_index] >> 8; table->backlight_thresholds[i] = - backlight_8_to_16(query_input_8bit); + cpu_to_be16(DIV_ROUNDUP((i * 65536), num_entries)); table->backlight_offsets[i] = - backlight_8_to_16(query_output_8bit); + cpu_to_be16(params.backlight_lut_array[lut_index]); } } @@ -212,8 +202,6 @@ static void fill_backlight_transform_table_v_2_2(struct dmcu_iram_parameters par { unsigned int i; unsigned int num_entries = NUM_BL_CURVE_SEGS; - unsigned int query_input_8bit; - unsigned int query_output_8bit; unsigned int lut_index; table->backlight_thresholds[0] = 0; @@ -231,16 +219,13 @@ static void fill_backlight_transform_table_v_2_2(struct dmcu_iram_parameters par * format U4.10. */ for (i = 1; i+1 < num_entries; i++) { - query_input_8bit = DIV_ROUNDUP((i * 256), num_entries); - lut_index = (params.backlight_lut_array_size - 1) * i / (num_entries - 1); ASSERT(lut_index < params.backlight_lut_array_size); - query_output_8bit = params.backlight_lut_array[lut_index] >> 8; table->backlight_thresholds[i] = - backlight_8_to_16(query_input_8bit); + cpu_to_be16(DIV_ROUNDUP((i * 65536), num_entries)); table->backlight_offsets[i] = - backlight_8_to_16(query_output_8bit); + cpu_to_be16(params.backlight_lut_array[lut_index]); } }