6.12-stable review patch. If anyone has any objections, please let me know.
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From: Samuel Holland samuel.holland@sifive.com
commit bc7acc0bd0f94c26bc0defc902311794a3d0fae9 upstream.
commit 7f00be96f125 ("of: property: Add device link support for interrupt-parent, dmas and -gpio(s)") started adding device links for the interrupt-parent property. commit 4104ca776ba3 ("of: property: Add fw_devlink support for interrupts") and commit f265f06af194 ("of: property: Fix fw_devlink handling of interrupts/interrupts-extended") later added full support for parsing the interrupts and interrupts-extended properties, which includes looking up the node of the parent domain. This made the handler for the interrupt-parent property redundant.
In fact, creating device links based solely on interrupt-parent is problematic, because it can create spurious cycles. A node may have this property without itself being an interrupt controller or consumer. For example, this property is often present in the root node or a /soc bus node to set the default interrupt parent for child nodes. However, it is incorrect for the bus to depend on the interrupt controller, as some of the bus's children may not be interrupt consumers at all or may have a different interrupt parent.
Resolving these spurious dependency cycles can cause an incorrect probe order for interrupt controller drivers. This was observed on a RISC-V system with both an APLIC and IMSIC under /soc, where interrupt-parent in /soc points to the APLIC, and the APLIC msi-parent points to the IMSIC. fw_devlink found three dependency cycles and attempted to probe the APLIC before the IMSIC. After applying this patch, there were no dependency cycles and the probe order was correct.
Acked-by: Marc Zyngier maz@kernel.org Cc: stable@vger.kernel.org Fixes: 4104ca776ba3 ("of: property: Add fw_devlink support for interrupts") Signed-off-by: Samuel Holland samuel.holland@sifive.com Link: https://lore.kernel.org/r/20241120233124.3649382-1-samuel.holland@sifive.com Signed-off-by: Rob Herring (Arm) robh@kernel.org Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org --- drivers/of/property.c | 2 -- 1 file changed, 2 deletions(-)
--- a/drivers/of/property.c +++ b/drivers/of/property.c @@ -1213,7 +1213,6 @@ DEFINE_SIMPLE_PROP(iommus, "iommus", "#i DEFINE_SIMPLE_PROP(mboxes, "mboxes", "#mbox-cells") DEFINE_SIMPLE_PROP(io_channels, "io-channels", "#io-channel-cells") DEFINE_SIMPLE_PROP(io_backends, "io-backends", "#io-backend-cells") -DEFINE_SIMPLE_PROP(interrupt_parent, "interrupt-parent", NULL) DEFINE_SIMPLE_PROP(dmas, "dmas", "#dma-cells") DEFINE_SIMPLE_PROP(power_domains, "power-domains", "#power-domain-cells") DEFINE_SIMPLE_PROP(hwlocks, "hwlocks", "#hwlock-cells") @@ -1359,7 +1358,6 @@ static const struct supplier_bindings of { .parse_prop = parse_mboxes, }, { .parse_prop = parse_io_channels, }, { .parse_prop = parse_io_backends, }, - { .parse_prop = parse_interrupt_parent, }, { .parse_prop = parse_dmas, .optional = true, }, { .parse_prop = parse_power_domains, }, { .parse_prop = parse_hwlocks, },