Re: [Buildroot] [PATCH 2/3] package/freescale-imx/imx-gpu-viv: add IMX8 framebuffer support

[Thomas Petazzoni via buildroot <buildroot@buildroot.org>]

On Tue, 10 Jan 2023 09:33:14 +0000
Lang Daniel via buildroot <buildroot@buildroot.org> wrote:

> According to meta-freescale [0] the framebuffer output can be enabled on
> IMX8 by using the wayland libraries together with egl.pc.
> 
> Tested on an imx8mn by running kmscube. EGL and GLES support detected.

Indeed. I've seen something similar on the Vivante binaries used on
STM32MP1 platforms, where the "framebuffer" libs are linked against
libwayland even though they don't use it.

> -# Libraries are linked against libdrm, except framebuffer output on ARM
> +# Libraries are linked against libdrm and wayland, except framebuffer output on ARM
>  ifneq ($(IMX_GPU_VIV_LIB_TARGET)$(BR2_arm),fby)
> -IMX_GPU_VIV_DEPENDENCIES += libdrm
> -endif
> -
> -ifeq ($(IMX_GPU_VIV_LIB_TARGET),wayland)
> -IMX_GPU_VIV_DEPENDENCIES += wayland
> +IMX_GPU_VIV_DEPENDENCIES += libdrm wayland
>  endif
>  
>  define IMX_GPU_VIV_EXTRACT_CMDS
>       $(call NXP_EXTRACT_HELPER,$(IMX_GPU_VIV_DL_DIR)/$(IMX_GPU_VIV_SOURCE))
>  endef
>  
> -ifeq ($(IMX_GPU_VIV_LIB_TARGET),fb)
> +ifeq ($(IMX_GPU_VIV_LIB_TARGET)$(BR2_arm),fby)
> +IMX_GPU_VIV_BACKEND_DIR = fb
>  define IMX_GPU_VIV_FIXUP_PKGCONFIG
>       ln -sf egl_linuxfb.pc $(@D)/gpu-core/usr/lib/pkgconfig/egl.pc
>  endef
> -else ifeq ($(IMX_GPU_VIV_LIB_TARGET),wayland)
> +else
> +# Framebuffer output on IMX8 (ARM64) uses egl.pc
> +# and the same libraries as the wayland backend.
> +IMX_GPU_VIV_BACKEND_DIR = wayland
> +ifeq ($(IMX_GPU_VIV_LIB_TARGET),wayland)
>  define IMX_GPU_VIV_FIXUP_PKGCONFIG
>       ln -sf egl_wayland.pc $(@D)/gpu-core/usr/lib/pkgconfig/egl.pc
>  endef
>  endif
> +endif

On this second part I'm a bit confused because in the "fb" case on
ARM64 you're don't have any egl.pc pkgconfig fixup. Are you sure this
is normal?

Indeed the code you have does this:

if framebuffer output and ARM:
	install egl.pc as a symlink to egl_linuxfb.pc
else:
	if wayland output:
		install egl.pc as a symlink to egl_wayland.pc

which means that in the framebuffer case on ARM64, you're not
installing any egl.pc symlink. Is this really OK?

Thanks!

Thomas
-- 
Thomas Petazzoni, co-owner and CEO, Bootlin
Embedded Linux and Kernel engineering and training
https://bootlin.com
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