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From 84a7f9c2e82fa06614068be2fa13c389d75477b5 Mon Sep 17 00:00:00 2001
From: Anthony Koo <Anthony.Koo@amd.com>
Date: Wed, 30 Jan 2019 11:05:38 -0500
Subject: [PATCH 1261/2940] 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 <Anthony.Koo@amd.com>
Reviewed-by: Aric Cyr <Aric.Cyr@amd.com>
Acked-by: Leo Li <sunpeng.li@amd.com>
---
.../amd/display/modules/power/power_helpers.c | 23 ++++---------------
1 file changed, 4 insertions(+), 19 deletions(-)
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 3ba87b076287..038b88221c5f 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]);
}
}
--
2.17.1
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