lkml.org 
[lkml]   [2023]   [Sep]   [5]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
/
From
Subject[PATCH 0/2] irqchip/gic-v3: Enable non-coherent GIC designs probing
Date
The GICv3 architecture specifications provide a means for the
system programmer to set the shareability and cacheability
attributes the GIC components (redistributors and ITSes) use
to drive memory transactions.

Albeit the architecture give control over shareability/cacheability
memory transactions attributes (and barriers), it is allowed to
connect the GIC interconnect ports to non-coherent memory ports
on the interconnect, basically tying off shareability/cacheability
"wires" and de-facto making the redistributors and ITSes non-coherent
memory observers.

This series aims at starting a discussion over a possible solution
to this problem, by adding to the GIC device tree bindings the
standard dma-noncoherent property. The GIC driver uses the property
to force the redistributors and ITSes shareability attributes to
non-shareable, which consequently forces the driver to use CMOs
on GIC memory tables.

On ARM DT DMA is default non-coherent, so the GIC driver can't rely
on the generic DT dma-coherent/non-coherent property management layer
(of_dma_is_coherent()) which would default all GIC designs in the field
as non-coherent; it has to rely on ad-hoc dma-noncoherent property handling.

When a consistent approach is agreed upon for DT an equivalent binding will
be put forward for ACPI based systems.

Lorenzo Pieralisi (2):
dt-bindings: interrupt-controller: arm,gic-v3: Add dma-noncoherent
property
irqchip/gic-v3: Enable non-coherent redistributors/ITSes probing

.../interrupt-controller/arm,gic-v3.yaml | 8 ++++++++
drivers/irqchip/irq-gic-v3-its.c | 19 +++++++++++++++----
2 files changed, 23 insertions(+), 4 deletions(-)

--
2.34.1

\
 
 \ /
  Last update: 2023-09-05 18:38    [W:0.292 / U:0.388 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site