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Tue, 26 May 2026 14:01:03 -0700 (PDT) Received: from localhost.localdomain ([187.17.229.0]) by smtp.gmail.com with ESMTPSA id 5a478bee46e88-30451ef3273sm15404389eec.2.2026.05.26.14.00.56 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Tue, 26 May 2026 14:01:02 -0700 (PDT) From: Edson Juliano Drosdeck To: harry.wentland@amd.com Cc: sunpeng.li@amd.com, siqueira@igalia.com, alexander.deucher@amd.com, christian.koenig@amd.com, airlied@gmail.com, simona@ffwll.ch, mario.limonciello@amd.com, alex.hung@amd.com, Wayne.Lin@amd.com, timur.kristof@gmail.com, superm1@kernel.org, aurabindo.pillai@amd.com, ivan.lipski@amd.com, chen-yu.chen@amd.com, amd-gfx@lists.freedesktop.org, dri-devel@lists.freedesktop.org, linux-kernel@vger.kernel.org, edson.drosdeck@gmail.com Subject: [PATCH] drm/amd/display: Avoid using zero AC/DC brightness levels Date: Tue, 26 May 2026 18:00:48 -0300 Message-ID: <20260526210048.1162477-1-edson.drosdeck@gmail.com> X-Mailer: git-send-email 2.47.3 Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable Content-Type: text/plain; charset="utf-8" Some systems report zero AC/DC brightness levels during backlight initialization, causing the panel brightness to start at the minimum level on boot. Only use the firmware brightness levels when both AC and DC values are non-zero Signed-off-by: Edson Juliano Drosdeck --- drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c | 4 +++- 1 file changed, 3 insertions(+), 1 deletion(-) diff --git a/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c b/drivers/gp= u/drm/amd/display/amdgpu_dm/amdgpu_dm.c index 5fc5d5608506..f947ce2a8625 100644 --- a/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c +++ b/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c @@ -5380,7 +5380,9 @@ amdgpu_dm_register_backlight_device(struct amdgpu_dm_= connector *aconnector) } =20 caps =3D &dm->backlight_caps[aconnector->bl_idx]; - if (get_brightness_range(caps, &min, &max)) { + if (get_brightness_range(caps, &min, &max) && + caps->ac_level > 0 && + caps->dc_level > 0) { if (power_supply_is_system_supplied() > 0) props.brightness =3D DIV_ROUND_CLOSEST((max - min) * caps->ac_level, 10= 0); else --=20 2.47.3