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([2401:4900:c920:95f0:34f7:c1ca:5f91:2fb9]) by smtp.gmail.com with ESMTPSA id a92af1059eb24-169a6021e49sm14204812c88.20.2026.10.10.05.49.38 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Sat, 10 Oct 2026 05:49:41 -0700 (PDT) From: chitranshmandhaniya@gmail.com To: hansg@kernel.org, ilpo.jarvinen@linux.intel.com, rafael@kernel.org Cc: lenb@kernel.org, platform-driver-x86@vger.kernel.org, linux-acpi@vger.kernel.org, linux-kernel@vger.kernel.org, Chitransh_Mandhaniya@dell.com Subject: [PATCH v5] ACPI: video: force native backlight on Dell OptiPlex AIO 7410 35W Date: Sat, 10 Oct 2026 18:18:30 +0530 Message-ID: <20261010124830.116750-1-chitranshmandhaniya@gmail.com> X-Mailer: git-send-email 2.43.0 In-Reply-To: <20261009072401.52509-1-chitranshmandhaniya@gmail.com> References: <20261009072401.52509-1-chitranshmandhaniya@gmail.com> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit From: Chitransh Mandhaniya The Dell OptiPlex AIO 7410 35W (board 01KP8D) declares DELL0501 in its ACPI DSDT (status = 0x0F) even though no UART scalar board is physically present. This causes acpi_video_get_backlight_type() to return acpi_backlight_dell_uart, which makes i915 skip registering intel_backlight. The dell-uart-backlight driver then times out talking to the absent board and the probe fails, leaving the machine with zero backlight control. A BIOS update fixes this on some models (e.g. OptiPlex 7420, board 0914RT) by setting DELL0501 _STA to 0, but Dell has not shipped a corrected BIOS for the 7410 even in the latest release (1.37.0, 2026-05-28). Add a DMI quirk to force native backlight on this model so that i915 registers intel_backlight and brightness control works out of the box. Tested on: - OptiPlex AIO 7410 35W (01KP8D, BIOS 1.37.0) -- confirmed acpi_backlight=native produces working intel_backlight (raw, max=96000), DMI quirk has the same effect. - OptiPlex AIO 7420 35W (0914RT, BIOS 1.27.0) -- DELL0501 absent in updated BIOS, intel_backlight works natively (no regression). Signed-off-by: Chitransh Mandhaniya --- drivers/acpi/video_detect.c | 8 ++++++++ 1 file changed, 8 insertions(+) diff --git a/drivers/acpi/video_detect.c b/drivers/acpi/video_detect.c index e3b69f876d24..1af14e04e597 100644 --- a/drivers/acpi/video_detect.c +++ b/drivers/acpi/video_detect.c @@ -883,6 +883,14 @@ static const struct dmi_system_id video_detect_dmi_table[] = { DMI_MATCH(DMI_PRODUCT_NAME, "OptiPlex 7770 AIO"), }, }, + { + .callback = video_detect_force_native, + /* Dell OptiPlex AIO 7410 35W */ + .matches = { + DMI_MATCH(DMI_SYS_VENDOR, "Dell Inc."), + DMI_MATCH(DMI_PRODUCT_NAME, "OptiPlex AIO 7410 35W"), + }, + }, /* * Models which have nvidia-ec-wmi support, but should not use it. -- 2.43.0