[PATCH] ARM: dts: bcm2835: Enable 3D rendering through V3D

[Stefan Wahren]

Hi Maíra,

[add Phil & Dave]

Am 12.04.24 um 15:25 schrieb Maíra Canal:
> RPi 0-3 is packed with a GPU that provides 3D rendering capabilities to
> the RPi. Currently, the downstream kernel uses an overlay to enable the
> GPU and use GPU hardware acceleration. When deploying a mainline kernel
> to the RPi 0-3, we end up without any GPU hardware acceleration
> (essentially, we can't use the OpenGL driver).
>
> Therefore, enable the V3D core for the RPi 0-3 in the mainline kernel.
thanks for trying to improve the combination Raspberry Pi OS + Mainline
Kernel. I think i'm able to reproduce the issue with Raspberry Pi 3 B +
on Buster. From the kernel side everything looks good:

[   11.054833] vc4-drm soc:gpu: bound 3f902000.hdmi (ops vc4_hdmi_ops [vc4])
[   11.055118] vc4-drm soc:gpu: bound 3f806000.vec (ops vc4_vec_ops [vc4])
[   11.055340] vc4-drm soc:gpu: bound 3f004000.txp (ops vc4_txp_ops [vc4])
[   11.055521] vc4-drm soc:gpu: bound 3f206000.pixelvalve (ops
vc4_crtc_ops [vc4])
[   11.055695] vc4-drm soc:gpu: bound 3f207000.pixelvalve (ops
vc4_crtc_ops [vc4])
[   11.055874] vc4-drm soc:gpu: bound 3f807000.pixelvalve (ops
vc4_crtc_ops [vc4])
[   11.056020] vc4-drm soc:gpu: bound 3fc00000.v3d (ops vc4_v3d_ops [vc4])
[   11.063277] Bluetooth: hci0: BCM4345C0
'brcm/BCM4345C0.raspberrypi,3-model-b-plus.hcd' Patch
[   11.070466] [drm] Initialized vc4 0.0.0 20140616 for soc:gpu on minor 0
[   11.174803] Console: switching to colour frame buffer device 240x75
[   11.205125] vc4-drm soc:gpu: [drm] fb0: vc4drmfb frame buffer device

But in Raspberry Pi OS there is a systemd script which is trying to
check for the V3D driver /usr/lib/systemd/scripts/gldriver_test.sh
Within the first check "raspi-config nonint is_kms" is called, which
always seems to fail. If i run strace on this command it seems to check
for /proc/device-tree/soc/v3d at 7ec00000/status which doesn't exists in
the Mainline device tree.

Maybe there is a chance to improve the userspace tool?

>
> Signed-off-by: Maíra Canal <mcanal at igalia.com>
> ---
>
> I decided to add the status property to the `bcm2835-common.dtsi`, but
> there are two other options:
>
> 1. To add the status property to the `bcm2835-rpi-common.dtsi` file
> 2. To add the status property to each individual RPi model, e.g.
> `bcm2837-rpi-3-b.dts`.
>
> Let me know which option is more suitable, and if `bcm2835-common.dtsi`
> is not the best option, I can send a v2.
>
> Best Regards,
> - Maíra
>
>   arch/arm/boot/dts/broadcom/bcm2835-common.dtsi | 1 +
>   1 file changed, 1 insertion(+)
>
> diff --git a/arch/arm/boot/dts/broadcom/bcm2835-common.dtsi b/arch/arm/boot/dts/broadcom/bcm2835-common.dtsi
> index 9261b67dbee1..851a6bce1939 100644
> --- a/arch/arm/boot/dts/broadcom/bcm2835-common.dtsi
> +++ b/arch/arm/boot/dts/broadcom/bcm2835-common.dtsi
> @@ -139,6 +139,7 @@ v3d: v3d at 7ec00000 {
>   			compatible = "brcm,bcm2835-v3d";
>   			reg = <0x7ec00000 0x1000>;
>   			interrupts = <1 10>;
> +			status = "okay";
>   		};
>
>   		vc4: gpu {