refactor(gicv3): clarify redistributor base address usage with USE_GIC_DRIVER=3
The GICv3 driver has 2 methods of discovering the redistributors:
a) via setting gicr_base - done at boot and assumes all GICR frames are
contiguous. This is the original method.
b) via gicv3_rdistif_probe() - called from platform code and requires
gicr_base == 0. It relaxes the requirement for frames to be
contiguous, like in a multichip configuration, and defers the
discovery to core bringup. This was introduced later.
Configurations possible with option a) are also possible with option b)
with only slightly different behaviour. USE_GIC_DRIVER=3 inherited
option b) from plat_gicv3_base.c and as such option a) is unusable.
However, it is unclear from code how this should be used. Clarify this
by requiring platforms initialise with gic_set_gicr_frames() and
adding relevant comments.
Also rename plat_arm_override_gicr_frames() to gic_set_gicr_frames() as
this is not plat arm specific and a part of the generic GIC driver.
Change-Id: I61d77211f8e65dc54cf9904069b500d26a06b5a5
Signed-off-by: Boyan Karatotev <boyan.karatotev@arm.com>
diff --git a/docs/getting_started/build-options.rst b/docs/getting_started/build-options.rst
index 6d3fea1..23de63f 100644
--- a/docs/getting_started/build-options.rst
+++ b/docs/getting_started/build-options.rst
@@ -1336,7 +1336,9 @@
- ``2``: use the GICv2 driver
- ``3``: use the GICv3 driver. See the next section on how to further configure
- it. Use this option for GICv4 implementations.
+ it. Use this option for GICv4 implementations. Requires calling
+ ``gic_set_gicr_frames()``.
+
- ``5``: use the EXPERIMENTAL GICv5 driver. Requires ``ENABLE_FEAT_GCIE=1``.
For GIC driver versions other than ``1``, deciding when to save and restore GIC