FAILED: patch "[PATCH] drm/amd/display: Fix AMDGPU_MAX_BL_LEVEL value" failed to apply to 6.15-stable tree

[<gregkh@linuxfoundation.org>]

The patch below does not apply to the 6.15-stable tree.
If someone wants it applied there, or to any other stable or longterm
tree, then please email the backport, including the original git commit
id to <stable@vger.kernel.org>.

To reproduce the conflict and resubmit, you may use the following commands:

git fetch https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/ linux-6.15.y
git checkout FETCH_HEAD
git cherry-pick -x 66abb996999de0d440a02583a6e70c2c24deab45
# <resolve conflicts, build, test, etc.>
git commit -s
git send-email --to '<stable@vger.kernel.org>' --in-reply-to '2025063040-sanctity-jolly-859c@gregkh' --subject-prefix 'PATCH 6.15.y' HEAD^..

Possible dependencies:



thanks,

greg k-h

------------------ original commit in Linus's tree ------------------

From 66abb996999de0d440a02583a6e70c2c24deab45 Mon Sep 17 00:00:00 2001
From: Mario Limonciello <mario.limonciello@amd.com>
Date: Mon, 23 Jun 2025 12:11:13 -0500
Subject: [PATCH] drm/amd/display: Fix AMDGPU_MAX_BL_LEVEL value

[Why]
commit 16dc8bc27c2a ("drm/amd/display: Export full brightness range to
userspace") adjusted the brightness range to scale to larger values, but
missed updating AMDGPU_MAX_BL_LEVEL which is needed to make sure that
scaling works properly with custom brightness curves.

[How]
As the change for max brightness of 0xFFFF only applies to devices
supporting DC, use existing DC define MAX_BACKLIGHT_LEVEL.

Fixes: 16dc8bc27c2a ("drm/amd/display: Export full brightness range to userspace")
Acked-by: Alex Deucher <alexander.deucher@amd.com>
Link: https://lore.kernel.org/r/20250623171114.1156451-1-mario.limonciello@amd.com
Signed-off-by: Mario Limonciello <mario.limonciello@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>
(cherry picked from commit 5b852044eb0d3e1f1c946d32e05fcb068e0a20a0)
Cc: stable@vger.kernel.org

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 bc4cd11bfc79..0b8ac9edc070 100644
--- a/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c
+++ b/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c
@@ -4718,16 +4718,16 @@ static int get_brightness_range(const struct amdgpu_dm_backlight_caps *caps,
 	return 1;
 }
 
-/* Rescale from [min..max] to [0..AMDGPU_MAX_BL_LEVEL] */
+/* Rescale from [min..max] to [0..MAX_BACKLIGHT_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);
+	return DIV_ROUND_CLOSEST_ULL(input * MAX_BACKLIGHT_LEVEL, max - min);
 }
 
-/* Rescale from [0..AMDGPU_MAX_BL_LEVEL] to [min..max] */
+/* Rescale from [0..MAX_BACKLIGHT_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);
+	return min + DIV_ROUND_CLOSEST_ULL(input * (max - min), MAX_BACKLIGHT_LEVEL);
 }
 
 static void convert_custom_brightness(const struct amdgpu_dm_backlight_caps *caps,
@@ -4947,7 +4947,7 @@ 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 = props.max_brightness = AMDGPU_MAX_BL_LEVEL;
+		props.brightness = props.max_brightness = MAX_BACKLIGHT_LEVEL;
 
 	if (caps->data_points && !(amdgpu_dc_debug_mask & DC_DISABLE_CUSTOM_BRIGHTNESS_CURVE))
 		drm_info(drm, "Using custom brightness curve\n");