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Tue, 01 Sep 2026 07:02:21 -0700 (PDT) Received: from loontop ([163.61.5.136]) by smtp.gmail.com with ESMTPSA id d9443c01a7336-2d7594fc0b3sm53833895ad.16.2026.09.01.07.02.11 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Tue, 01 Sep 2026 07:02:15 -0700 (PDT) From: Aarav Kumar To: amd-gfx@lists.freedesktop.org Cc: dri-devel@lists.freedesktop.org, linux-kernel@vger.kernel.org, harry.wentland@amd.com, sunpeng.li@amd.com, siqueira@igalia.com, alexander.deucher@amd.com, christian.koenig@amd.com, ray.wu@amd.com, Aarav Kumar Subject: [PATCH] drm/amd/display: use linear backlight curve on Linux Date: Tue, 1 Sep 2026 19:31:55 +0530 Message-ID: <20260901140155.19129-1-aarav.240604@gmail.com> X-Mailer: git-send-email 2.55.0 Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit The power module currently uses a non-linear backlight curve for the Linux backlight path. This results in incorrect brightness levels on affected systems. Use the linear backlight curve instead to preserve the existing brightness-to-PWM mapping. Tested on an AMD laptop with an eDP panel. The regression was reproduced with commit 3c108046e1d6 ("drm/amd/display: Add power module on Linux"), and the brightness behavior was restored with this change. Fixes: 3c108046e1d6 ("drm/amd/display: Add power module on Linux") Link: https://gitlab.freedesktop.org/drm/amd/-/work_items/5723 Signed-off-by: Aarav Kumar --- drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) 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 8d690468d..cd10a5d45 100644 --- a/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c +++ b/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c @@ -1913,7 +1913,7 @@ static int amdgpu_dm_init_power_module(struct amdgpu_display_manager *dm) !(amdgpu_dc_feature_mask & DC_DISABLE_FRACTIONAL_PWM_MASK); init_data[i].use_custom_backlight_caps = false; init_data[i].custom_backlight_caps_config_no = 0; - init_data[i].use_linear_backlight_curve = false; + init_data[i].use_linear_backlight_curve = true; init_data[i].def_varibright_enable = 0; init_data[i].varibright_level = 0; /* -- 2.55.0