Thread (35 messages) 35 messages, 6 authors, 2024-02-02

Re: [RFC PATCH v2 06/21] RISC-V: Kconfig: Select deferred GSI probe for ACPI systems

From: Bjorn Helgaas <helgaas@kernel.org>
Date: 2023-10-26 17:04:24
Also in: linux-acpi, linux-pci, linux-riscv, linux-serial, lkml

On Thu, Oct 26, 2023 at 01:53:29AM +0530, Sunil V L wrote:
On RISC-V platforms, apart from root interrupt controllers (which
provide local interrupts and IPI), other interrupt controllers in the
hierarchy are probed late. Enable this select this CONFIG option for
RISC-V platforms so that device drivers which connect to deferred
interrupt controllers can take appropriate action.
Quite a bit of this series seems related to the question of interrupt
controllers being probed "late".

I don't see anything specific about *how* late this might be, but from
the use of -EPROBE_DEFER in individual drivers (8250_pnp explicitly,
and acpi_register_gsi() and pnp_irq() and acpi_pci_irq_enable(), which
are called from driver .probe() paths) it seems like interrupt
controllers might be detected even after devices that use them.

That seems like a fairly invasive change to the driver probe flow.
If we really need to do that, I think it might merit a little more
background as justification since we haven't had to do it for any
other arch yet.

Bjorn
quoted hunk ↗ jump to hunk
Signed-off-by: Sunil V L <sunilvl@ventanamicro.com>
---
 arch/riscv/Kconfig | 1 +
 1 file changed, 1 insertion(+)
diff --git a/arch/riscv/Kconfig b/arch/riscv/Kconfig
index 8c105a151e12..b62441aefa6a 100644
--- a/arch/riscv/Kconfig
+++ b/arch/riscv/Kconfig
@@ -12,6 +12,7 @@ config 32BIT
 
 config RISCV
 	def_bool y
+	select ARCH_ACPI_DEFERRED_GSI if ACPI
 	select ACPI_GENERIC_GSI if ACPI
 	select ACPI_MCFG if (ACPI && PCI)
 	select ACPI_REDUCED_HARDWARE_ONLY if ACPI
-- 
2.39.2


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