[PATCH] mesa: Fix a case when gbm is enabled but DRIDRIVERS is not defined

[Khem Raj <raj.khem@gmail.com>]

This is a typical scenario with arm platforms, with meson if DRIDRIVERS
is empty then dri is disabled automatically, but gbm needs dri2 enabled
for it to have proper backend, in autotools we could use --enable-gbm
--enable-dri and get correct behaviour but with meson enabling dri2 only
works if DRIDRIVERS is not empty

This fixes mesa-gl build for rpi machines when using userland graphics

Signed-off-by: Khem Raj <raj.khem@gmail.com>
---
 .../mesa/files/dri-drivers-auto.patch         | 31 +++++++++++++++++++
 meta/recipes-graphics/mesa/mesa_19.0.3.bb     |  1 +
 2 files changed, 32 insertions(+)
 create mode 100644 meta/recipes-graphics/mesa/files/dri-drivers-auto.patch

diff --git a/meta/recipes-graphics/mesa/files/dri-drivers-auto.patch b/meta/recipes-graphics/mesa/files/dri-drivers-auto.patch
new file mode 100644
index 0000000000..532b2370b3
--- /dev/null
+++ b/meta/recipes-graphics/mesa/files/dri-drivers-auto.patch
@@ -0,0 +1,31 @@
+Fix meson regression for --enable-dri --enable-gbm combo equivalent
+
+For arm if DRIDRIVERS is set to 'auto' then respect that
+to enable dri support, this is required for devices where
+we use mesa to provide gl/libgbm implementation and rest
+comes from some proprietary driver, typical case is userland
+graphics driver for raspberrypi devices.
+
+This would mean that when we set 
+
+DRIDRIVERS_rpi = ",auto"
+
+Then the meson system will build the dri with gbm backend
+as was the case with autotools where --enable-dri did the
+same thing
+
+Upstream-Status: Inappropriate [Might be specific to arm systems]
+
+Signed-off-by: Khem Raj <raj.khem@gmail.com>
+
+--- a/meson.build
++++ b/meson.build
+@@ -98,7 +98,7 @@ if _drivers.contains('auto')
+     if ['x86', 'x86_64'].contains(host_machine.cpu_family())
+       _drivers = ['i915', 'i965', 'r100', 'r200', 'nouveau']
+     elif ['arm', 'aarch64'].contains(host_machine.cpu_family())
+-      _drivers = []
++      _drivers = ['auto']
+     else
+       error('Unknown architecture @0@. Please pass -Ddri-drivers to set driver options. Patches gladly accepted to fix this.'.format(
+             host_machine.cpu_family()))
diff --git a/meta/recipes-graphics/mesa/mesa_19.0.3.bb b/meta/recipes-graphics/mesa/mesa_19.0.3.bb
index 36faa4a99d..c1703e04d2 100644
--- a/meta/recipes-graphics/mesa/mesa_19.0.3.bb
+++ b/meta/recipes-graphics/mesa/mesa_19.0.3.bb
@@ -3,6 +3,7 @@ require ${BPN}.inc
 SRC_URI = "https://mesa.freedesktop.org/archive/mesa-${PV}.tar.xz \
            file://0001-meson.build-check-for-all-linux-host_os-combinations.patch \
            file://0001-meson.build-make-TLS-GLX-optional-again.patch \
+           file://dri-drivers-auto.patch \
            "
 
 SRC_URI[md5sum] = "d03bf14e42c0e54ebae5730712ccc408"
-- 
2.21.0