On certain Loongson platforms, drivers attempting to request a legacy
ISA IRQ directly via request_irq() (e.g., IRQ 4) may fail. The
virtual IRQ descriptor is not fully initialized and lacks a valid irqchip.
This issue does not affect ACPI-enumerated devices described in DSDT,
as their interrupts are properly mapped via the GSI translation path.
This indicates the LPC irqdomain itself is functional but is not correctly
handling direct VIRQ-to-HWIRQ mappings.
The root cause is the use of irq_domain_create_linear(). This API sets
up a domain for dynamic, on-demand mapping, typically triggered by a GSI
request. It does not pre-populate the mappings for the legacy VIRQ range
(0-15). Consequently, if no ACPI device claims a specific GSI
(e.g., GSI 4), the corresponding VIRQ (e.g., VIRQ 4) is never mapped to
the LPC domain. A direct call to request_irq(4, ...) then fails because
the kernel cannot resolve this VIRQ to a hardware interrupt managed by
the LPC controller.
The PCH-LPC interrupt controller is an i8259-compatible legacy device
that requires a deterministic, static 1-to-1 mapping for IRQs 0-15 to
support legacy drivers.
Fix this by replacing irq_domain_create_linear() with
irq_domain_create_legacy(). This API is specifically designed for such
controllers. It establishes the required static 1-to-1 VIRQ-to-HWIRQ
mapping for the entire legacy range (0-15) immediately upon domain
creation. This ensures that any VIRQ in this range is always resolvable,
making direct calls to request_irq() for legacy IRQs function correctly.
Signed-off-by: Ming Wang <wangming01@loongson.cn>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: maoxiaochuan <maoxiaochuan@loongson.cn>
avecintc_init() enables the Advanced Interrupt Controller (AVEC) of
the boot CPU node, but nothing enables the AVEC on secondary nodes.
Move the enablement to the CPU hotplug callback so that secondary nodes get
the AVEC enabled too. In theory enabling it once per node would be
sufficient, but redundant enabling does no hurt, so keep the code simple
and do it unconditionally.
Signed-off-by: Tianyang Zhang <zhangtianyang@loongson.cn>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Acked-by: Huacai Chen <chenhuacai@loongson.cn>
Link: https://lore.kernel.org/all/20250111023704.17285-1-zhangtianyang@loongson.cn
Signed-off-by: maoxiaochuan <maoxiaochuan@loongson.cn>
Ming Wang