From: Mario Limonciello mario.limonciello@amd.com

[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 Cc: stable@vger.kernel.org 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 --- .../gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c | 41 ++++++++++++------- 1 file changed, 27 insertions(+), 14 deletions(-)

diff --git a/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c b/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c index 31df545f8c0f..19d38357f508 100644 --- a/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c +++ b/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c @@ -4721,9 +4721,23 @@ static int get_brightness_range(const struct amdgpu_dm_backlight_caps *caps, return 1; }

+/* 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, - uint32_t *brightness) + 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;

@@ -4734,7 +4748,7 @@ 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; @@ -4745,17 +4759,18 @@ 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); } @@ -4768,11 +4783,10 @@ 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, @@ -4785,8 +4799,8 @@ 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); }

@@ -4936,11 +4950,10 @@ 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",