[yocto] [meta-raspberrypi][PATCH v2 4/4] README: Add a section about graphic stacks

[Javier Martinez Canillas]

This patch adds to the README a section that explains the RPi can different
graphics stacks and that the user can choose by manually changing providers.

Signed-off-by: Javier Martinez Canillas <javier at osg.samsung.com>

---

Changes in v2: None

 README | 9 +++++++++
 1 file changed, 9 insertions(+)

diff --git a/README b/README
index 678c0eb4a4e3..0569b353870c 100644
--- a/README
+++ b/README
@@ -25,6 +25,7 @@ Contents:
     2.K. Boot to U-Boot
     2.L. Image with Initramfs
     2.M. Device tree support
+    2.O. Graphic stacks
 3. Extra apps
     3.A. omxplayer
 4. Source code and mirrors
@@ -195,6 +196,14 @@ kernels.
 NOTE: KERNEL_DEVICETREE is default enabled for kernel >= 3.18 and always disabled for
       older kernel versions.
 
+2.O. Graphic stacks
+===================
+The Raspberry Pi boards can use one of two graphics stacks: The userland
+user-space driver or the vc4 DRM/KMS kernel driver. By default userland
+is used since the vc4 is still experimental. But this can be changed by
+modifying the defaults for the kernel, egl, gles2, libgl and mesa providers.
+This is explained in the conf/machine/include/rpi-default-providers.inc file.
+
 3. Extra apps
 =============
 
-- 
2.4.3