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drm/amd/display: Export full brightness range to userspace

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[WHY]
Userspace currently is offered a range from 0-0xFF but the PWM is
programmed from 0-0xFFFF.  This can be limiting to some software
that wants to apply greater granularity.

[HOW]
Convert internally to firmware values only when mapping custom
brightness curves because these are in 0-0xFF range. Advertise full
PWM range to userspace.

Cc: Mario Limonciello <mario.limonciello@amd.com>
Cc: Alex Deucher <alexander.deucher@amd.com>
Reviewed-by: Roman Li <roman.li@amd.com>
Signed-off-by: Mario Limonciello <mario.limonciello@amd.com>
Signed-off-by: Alex Hung <alex.hung@amd.com>
Tested-by: Daniel Wheeler <daniel.wheeler@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>
(cherry picked from commit 8dbd72cb79)
Cc: stable@vger.kernel.org
This commit is contained in:
Mario Limonciello 2025-05-29 09:46:32 -05:00 • committed by Alex Deucher
parent ffcaed1d7e
commit 16dc8bc27c
1 changed files with 28 additions and 15 deletions
Download patch file Download diff file Expand all files Collapse all files

43
drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c
View file

@ -4718,9 +4718,23 @@ static int get_brightness_range(const struct amdgpu_dm_backlight_caps *caps,
return 1;
}
static void convert_custom_brightness(const struct amdgpu_dm_backlight_caps *caps,
uint32_t *brightness)
/* Rescale from [min..max] to [0..AMDGPU_MAX_BL_LEVEL] */
static inline u32 scale_input_to_fw(int min, int max, u64 input)
{
return DIV_ROUND_CLOSEST_ULL(input * AMDGPU_MAX_BL_LEVEL, max - min);
}
/* Rescale from [0..AMDGPU_MAX_BL_LEVEL] to [min..max] */
static inline u32 scale_fw_to_input(int min, int max, u64 input)
{
return min + DIV_ROUND_CLOSEST_ULL(input * (max - min), AMDGPU_MAX_BL_LEVEL);
}
static void convert_custom_brightness(const struct amdgpu_dm_backlight_caps *caps,
unsigned int min, unsigned int max,
uint32_t *user_brightness)
{
u32 brightness = scale_input_to_fw(min, max, *user_brightness);
u8 prev_signal = 0, prev_lum = 0;
int i = 0;
@ -4731,7 +4745,7 @@ static void convert_custom_brightness(const struct amdgpu_dm_backlight_caps *cap
return;
/* choose start to run less interpolation steps */
if (caps->luminance_data[caps->data_points/2].input_signal > *brightness)
if (caps->luminance_data[caps->data_points/2].input_signal > brightness)
i = caps->data_points/2;
do {
u8 signal = caps->luminance_data[i].input_signal;
@ -4742,17 +4756,18 @@ static void convert_custom_brightness(const struct amdgpu_dm_backlight_caps *cap
* brightness < signal: interpolate between previous and current luminance numerator
* brightness > signal: find next data point
*/
if (*brightness > signal) {
if (brightness > signal) {
prev_signal = signal;
prev_lum = lum;
i++;
continue;
}
if (*brightness < signal)
if (brightness < signal)
lum = prev_lum + DIV_ROUND_CLOSEST((lum - prev_lum) *
(*brightness - prev_signal),
(brightness - prev_signal),
signal - prev_signal);
*brightness = DIV_ROUND_CLOSEST(lum * *brightness, 101);
*user_brightness = scale_fw_to_input(min, max,
DIV_ROUND_CLOSEST(lum * brightness, 101));
return;
} while (i < caps->data_points);
}
@ -4765,11 +4780,10 @@ static u32 convert_brightness_from_user(const struct amdgpu_dm_backlight_caps *c
if (!get_brightness_range(caps, &min, &max))
return brightness;
convert_custom_brightness(caps, &brightness);
convert_custom_brightness(caps, min, max, &brightness);
// Rescale 0..255 to min..max
return min + DIV_ROUND_CLOSEST((max - min) * brightness,
AMDGPU_MAX_BL_LEVEL);
// Rescale 0..max to min..max
return min + DIV_ROUND_CLOSEST_ULL((u64)(max - min) * brightness, max);
}
static u32 convert_brightness_to_user(const struct amdgpu_dm_backlight_caps *caps,
@ -4782,8 +4796,8 @@ static u32 convert_brightness_to_user(const struct amdgpu_dm_backlight_caps *cap
if (brightness < min)
return 0;
// Rescale min..max to 0..255
return DIV_ROUND_CLOSEST(AMDGPU_MAX_BL_LEVEL * (brightness - min),
// Rescale min..max to 0..max
return DIV_ROUND_CLOSEST_ULL((u64)max * (brightness - min),
max - min);
}
@ -4933,11 +4947,10 @@ amdgpu_dm_register_backlight_device(struct amdgpu_dm_connector *aconnector)
drm_dbg(drm, "Backlight caps: min: %d, max: %d, ac %d, dc %d\n", min, max,
caps->ac_level, caps->dc_level);
} else
props.brightness = AMDGPU_MAX_BL_LEVEL;
props.brightness = props.max_brightness = AMDGPU_MAX_BL_LEVEL;
if (caps->data_points && !(amdgpu_dc_debug_mask & DC_DISABLE_CUSTOM_BRIGHTNESS_CURVE))
drm_info(drm, "Using custom brightness curve\n");
props.max_brightness = AMDGPU_MAX_BL_LEVEL;
props.type = BACKLIGHT_RAW;
snprintf(bl_name, sizeof(bl_name), "amdgpu_bl%d",