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([171.61.163.171]) by smtp.gmail.com with ESMTPSA id d9443c01a7336-2a88b5d93cdsm166208305ad.70.2026.02.03.01.00.14 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Tue, 03 Feb 2026 01:00:16 -0800 (PST) From: Atharva Tiwari To: Cc: Atharva Tiwari , Hans de Goede , =?UTF-8?q?Ilpo=20J=C3=A4rvinen?= , platform-driver-x86@vger.kernel.org, linux-kernel@vger.kernel.org Subject: [PATCH] apple-gmux: preserve brightness using EFI Date: Tue, 3 Feb 2026 09:00:04 +0000 Message-ID: <20260203090007.13501-1-atharvatiwarilinuxdev@gmail.com> X-Mailer: git-send-email 2.43.0 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" Make apple-gmux save the current backlight brightness to EFI on shutdown, so the brightness level is preserved across reboots. EFI Code inspired from drivers/input/keyboard/applespi.c:1589 (tested on iMac20,1) Signed-off-by: Atharva Tiwari --- drivers/platform/x86/apple-gmux.c | 26 ++++++++++++++++++++++++++ 1 file changed, 26 insertions(+) diff --git a/drivers/platform/x86/apple-gmux.c b/drivers/platform/x86/apple= -gmux.c index 1417e230edbd..4e687b61c92f 100644 --- a/drivers/platform/x86/apple-gmux.c +++ b/drivers/platform/x86/apple-gmux.c @@ -22,6 +22,7 @@ #include #include #include +#include #include #include =20 @@ -107,6 +108,9 @@ struct apple_gmux_config { =20 # define MMIO_GMUX_MAX_BRIGHTNESS 0xffff =20 +#define EFI_BRIGHTNESS_NAME L"backlight-level" +#define EFI_BRIGHTNESS_GUID EFI_GUID(0x7c436110, 0xab2a, 0x4bbb, 0xa8, 0x= 80, 0xfe, 0x41, 0x99, 0x5c, 0x9f, 0x82) + static u8 gmux_pio_read8(struct apple_gmux_data *gmux_data, int port) { return inb(gmux_data->iostart + port); @@ -1012,6 +1016,27 @@ static void gmux_remove(struct pnp_dev *pnp) kfree(gmux_data); } =20 +static void gmux_shutdown(struct pnp_dev *pnp) +{ + struct apple_gmux_data *gmux_data =3D pnp_get_drvdata(pnp); + efi_status_t status =3D EFI_UNSUPPORTED; + u32 efi_attr; + u32 efi_data; + + gmux_remove(pnp); + + efi_data =3D (u16)gmux_get_brightness(gmux_data->bdev); + efi_attr =3D EFI_VARIABLE_NON_VOLATILE | EFI_VARIABLE_BOOTSERVICE_ACCESS| + EFI_VARIABLE_RUNTIME_ACCESS; + + if (efi_rt_services_supported(EFI_RT_SUPPORTED_SET_VARIABLE)) + status =3D efi.set_variable(EFI_BRIGHTNESS_NAME, &EFI_BRIGHTNESS_GUID, + efi_attr, sizeof(efi_data), &efi_data); + + if (status !=3D EFI_SUCCESS) + pr_warn("Unable to save brightness to EFI: 0x%lx\n", status); + +} static const struct pnp_device_id gmux_device_ids[] =3D { {GMUX_ACPI_HID, 0}, {"", 0} @@ -1026,6 +1051,7 @@ static struct pnp_driver gmux_pnp_driver =3D { .name =3D "apple-gmux", .probe =3D gmux_probe, .remove =3D gmux_remove, + .shutdown =3D gmux_shutdown, .id_table =3D gmux_device_ids, .driver =3D { .pm =3D &gmux_dev_pm_ops, --=20 2.43.0