[PATCH] x86/platform, acpi: Statically assign IRQ numbers in ACPI, hardware reduced mode

[Li, Aubrey]

We have to be conservative to dynamically assign IRQ number on the platform
in ACPI Hardware-reduced mode. On the Bay Trail-T(ASUS-T100) platform, there
is a RTC device still using the legacy hardcoded IRQ8, which could cause the
following error if RTC is configured:

7486341a98f: genirq: Flags mismatch irq 8. 00000080 (mmc0) vs. 00000000 (rtc0)

So we want to statically assign IRQ numbers in ACPI hardware reduced mode to
fix this error, this also matches with the original IRQ assignment policy.

Signed-off-by: Li Aubrey <aubrey.li@xxxxxxxxxxxxxxx>
Cc: Alan Cox <alan@xxxxxxxxxxxxxxx>
Cc: Len Brown <len.brown@xxxxxxxxx>
Cc: Rafael J. Wysocki <rafael.j.wysocki@xxxxxxxxx>
Cc: Arjan van de Ven <arjan@xxxxxxxxxxxxxxx>
---
 arch/x86/kernel/acpi/boot.c | 8 ++++++--
 1 file changed, 6 insertions(+), 2 deletions(-)

diff --git a/arch/x86/kernel/acpi/boot.c b/arch/x86/kernel/acpi/boot.c
index 803b684..4cd0761 100644
--- a/arch/x86/kernel/acpi/boot.c
+++ b/arch/x86/kernel/acpi/boot.c
@@ -460,8 +460,12 @@ acpi_parse_ioapic(struct acpi_subtable_header * header, const unsigned long end)
 
 	acpi_table_print_madt_entry(header);
 
-	/* Statically assign IRQ numbers for IOAPICs hosting legacy IRQs */
-	if (ioapic->global_irq_base < nr_legacy_irqs())
+	/*
+	 * Statically assign IRQ numbers for IOAPICs hosting legacy IRQs,
+	 * Or for the platform in Hardware-reduced ACPI model
+	 */
+	if (ioapic->global_irq_base < nr_legacy_irqs() ||
+		acpi_gbl_reduced_hardware)
 		cfg.type = IOAPIC_DOMAIN_LEGACY;
 
 	mp_register_ioapic(ioapic->id, ioapic->address, ioapic->global_irq_base,
-- 
1.9.1
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