package/freescale-imx/imx-gpu-viv: enable aarch64 framebuffer support

Back when the imx-gpu-viv package was enabled on AArch64 in commit
84afda9ca6dad5fd828ba94fa60df52c81cc7814, the fb output option was not
enabled.

However, according to meta-freescale [0] the framebuffer output can be
enabled on IMX8 by using the wayland libraries together with egl.pc.

[0] https://git.yoctoproject.org/meta-freescale/tree/recipes-graphics/imx-gpu-viv/imx-gpu-viv-6.inc

This commit does enable fb output on AArch64, which requires a few
precautions as the imx-gpu-viv logic is a bit convoluted:

- FB on ARM is supported using "pure" framebuffer libraries. However,
  a specific egl.pc is needed: egl_linuxfb.pc. The supporting
  libraries are found in the fb/ subdirectory in imx-gpu-viv "code".

- FB on AArch64 is supported using libraries that are linked with
  wayland and libdrm, even though wayland/libdrm is obviously not used
  for framebuffer output. pkg-config wise, this configuration can use
  the default egl.pc. The supporting libraries are found in the
  wayland/ subdirectory in imx-gpu-viv "code", as oddly as it seems.

- Wayland on ARM on AArch64 is supported using libraries that are
  obviously linked against wayland and libdrm. pkg-config wise, egl.pc
  needs to be symlinked to egl_wayland.pc.

This patch solves this situation by introducing a hidden boolean
option BR2_PACKAGE_IMX_GPU_VIV_USES_WAYLAND that indicates whether
wayland/libdrm is used by the currently selected output. This is of
course true when BR2_PACKAGE_IMX_GPU_VIV_OUTPUT_WL, but also when
BR2_PACKAGE_IMX_GPU_VIV_OUTPUT_FB on AArch64.

Signed-off-by: Daniel Lang <d.lang@abatec.at>
[Thomas: quite significant rework compared to the submission from
Daniel Lang, so we didn't keep the Reviewed-by from Gary Bisson]
Signed-off-by: Thomas Petazzoni <thomas.petazzoni@bootlin.com>

package/freescale-imx/imx-gpu-viv/Config.in

@@ -12,9 +12,6 @@ config BR2_PACKAGE_IMX_GPU_VIV
 	depends on (BR2_arm && BR2_ARM_EABIHF) || BR2_aarch64
 	# Library binaries are linked against libc.so.6
 	depends on BR2_TOOLCHAIN_USES_GLIBC
-	# Library binaries are linked against libdrm.so.2, except framebuffer
-	# output on ARM
-	select BR2_PACKAGE_LIBDRM if !(BR2_arm && BR2_PACKAGE_IMX_GPU_VIV_OUTPUT_FB)
 	select BR2_PACKAGE_HAS_LIBEGL
 	select BR2_PACKAGE_HAS_LIBGLES
 	# gbm is only available in the aarch64 blobs
@@ -34,6 +31,13 @@ config BR2_PACKAGE_IMX_GPU_VIV
 	  This library is provided by Freescale as-is and doesn't have
 	  an upstream.
 
+# Library binaries are linked against libdrm.so.2 and libwayland,
+# except framebuffer output on ARM
+config BR2_PACKAGE_IMX_GPU_VIV_USES_WAYLAND
+	bool
+	select BR2_PACKAGE_LIBDRM
+	select BR2_PACKAGE_WAYLAND
+
 if BR2_PACKAGE_IMX_GPU_VIV
 
 choice
@@ -45,12 +49,13 @@ choice
 
 config BR2_PACKAGE_IMX_GPU_VIV_OUTPUT_FB
 	bool "Framebuffer"
-	# The i.MX8 aarch64 blob doesn't support FB output
-	depends on BR2_arm
+	# Yes, the ARM64 framebuffer libraries link against
+	# libdrm/libwayland.
+	select BR2_PACKAGE_IMX_GPU_VIV_USES_WAYLAND if BR2_aarch64
 
 config BR2_PACKAGE_IMX_GPU_VIV_OUTPUT_WL
 	bool "Wayland"
-	select BR2_PACKAGE_WAYLAND
+	select BR2_PACKAGE_IMX_GPU_VIV_USES_WAYLAND
 
 endchoice
 

package/freescale-imx/imx-gpu-viv/imx-gpu-viv.mk

@@ -27,20 +27,24 @@ endif
 
 IMX_GPU_VIV_OUTPUT = $(call qstrip,$(BR2_PACKAGE_IMX_GPU_VIV_OUTPUT))
 
-# Libraries are linked against libdrm, except framebuffer output on ARM
-ifneq ($(IMX_GPU_VIV_OUTPUT)$(BR2_arm),fby)
-IMX_GPU_VIV_DEPENDENCIES += libdrm
-endif
-
-ifeq ($(IMX_GPU_VIV_OUTPUT),wayland)
-IMX_GPU_VIV_DEPENDENCIES += wayland
+ifeq ($(BR2_PACKAGE_IMX_GPU_VIV_USES_WAYLAND),y)
+IMX_GPU_VIV_DEPENDENCIES += libdrm wayland
+IMX_GPU_VIV_LIBDIR = wayland
+else
+IMX_GPU_VIV_LIBDIR = fb
 endif
 
 define IMX_GPU_VIV_EXTRACT_CMDS
 	$(call NXP_EXTRACT_HELPER,$(IMX_GPU_VIV_DL_DIR)/$(IMX_GPU_VIV_SOURCE))
 endef
 
-ifeq ($(IMX_GPU_VIV_OUTPUT),fb)
+# The package comes with multiple versions of egl.pc,
+# depending on the output the original egl.pc is replaced
+# with a symlink:
+# - arm/frambuffer: symlink to egl_linuxfb.pc
+# - aarch64/framebuffer: original egl.pc without a symlink
+# - wayland: symblink to egl_wayland.pc
+ifeq ($(IMX_GPU_VIV_OUTPUT):$(BR2_arm),fb:y)
 define IMX_GPU_VIV_FIXUP_PKGCONFIG
 	ln -sf egl_linuxfb.pc $(@D)/gpu-core/usr/lib/pkgconfig/egl.pc
 endef
@@ -61,7 +65,7 @@ endif
 # in the upstream archive here. We also remove unused backend files.
 # Make sure these commands are idempotent.
 define IMX_GPU_VIV_BUILD_CMDS
-	cp -dpfr $(@D)/gpu-core/usr/lib/$(IMX_GPU_VIV_OUTPUT)/* $(@D)/gpu-core/usr/lib/
+	cp -dpfr $(@D)/gpu-core/usr/lib/$(IMX_GPU_VIV_LIBDIR)/* $(@D)/gpu-core/usr/lib/
 	$(foreach backend,fb wayland, \
 		$(RM) -r $(@D)/gpu-core/usr/lib/$(backend)
 	)