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References: <20240515192009.14362-1-kendallsm2@icloud.com>
In-Reply-To: <20240515192009.14362-1-kendallsm2@icloud.com>
From: Alex Deucher <alexdeucher@gmail.com>
Date: Thu, 16 May 2024 10:18:24 -0400
Message-ID: <CADnq5_Mb1fDJ=Z8Knnyj5B1YRN+ni1_mmje+==-C9ytmX0Z1uQ@mail.gmail.com>
Subject: Re: [PATCH] drm/radeon: initialize atom DIG backlight for iMac12, 1
 and iMac12, 2 with Radeon 6750M
To: Kendall Smith <kendallsm2@icloud.com>
Cc: amd-gfx@lists.freedesktop.org, linux-kernel@vger.kernel.org
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Applied.  Thanks!

Alex

On Wed, May 15, 2024 at 5:47=E2=80=AFPM Kendall Smith <kendallsm2@icloud.co=
m> wrote:
>
> If a Radeon 6750M GPU from an iMac12,1 is installed into an iMac 12,2, th=
ere is no backlight device initialized during boot. Everything else is func=
tional, but the display brightness cannot be controlled. There are no direc=
tories present in /sys/class/backlight after booting. A simple one line mod=
ification to an if statement fixes this issue by initializing the radeon ba=
cklight device for an iMac12,2 as well if it has a 6750M. After the patch, =
brightness can be controlled and radeon_bl0 is present in /sys/class/backli=
ght. This was tested by compiling the latest kernel with and without the pa=
tch.
>
> Signed-off-by: Kendall Smith <kendallsm2@icloud.com>
> ---
>  drivers/gpu/drm/radeon/atombios_encoders.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/drivers/gpu/drm/radeon/atombios_encoders.c b/drivers/gpu/drm=
/radeon/atombios_encoders.c
> index 2bff0d9e20f5..7b11674f5d45 100644
> --- a/drivers/gpu/drm/radeon/atombios_encoders.c
> +++ b/drivers/gpu/drm/radeon/atombios_encoders.c
> @@ -201,7 +201,7 @@ void radeon_atom_backlight_init(struct radeon_encoder=
 *radeon_encoder,
>          */
>         if ((rdev->pdev->subsystem_vendor =3D=3D PCI_VENDOR_ID_APPLE) &&
>             (rdev->pdev->device =3D=3D 0x6741) &&
> -           !dmi_match(DMI_PRODUCT_NAME, "iMac12,1"))
> +           !(dmi_match(DMI_PRODUCT_NAME, "iMac12,1") || dmi_match(DMI_PR=
ODUCT_NAME, "iMac12,2")))
>                 return;
>
>         if (!radeon_encoder->enc_priv)
> --
> 2.34.1
>