From 9526486164818f1c59a142dec8a1f09fbf77669c Mon Sep 17 00:00:00 2001
From: Peter Maydell <peter.maydell@linaro.org>
Date: Fri, 6 Nov 2020 23:51:08 +0000
Subject: hw/m68k/q800: Don't connect two qemu_irqs directly to the same input
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The q800 board code connects both of the IRQ outputs of the ESCC
to the same pic[3] qemu_irq. Connecting two qemu_irqs outputs directly
to the same input is not valid as it produces subtly wrong behaviour
(for instance if both the IRQ lines are high, and then one goes
low, the PIC input will see this as a high-to-low transition
even though the second IRQ line should still be holding it high).

This kind of wiring needs an explicitly created OR gate; add one.

Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
Reviewed-by: Philippe Mathieu-Daudé <f4bug@amsat.org>
Reviewed-by: Laurent Vivier <laurent@vivier.eu>
Message-Id: <20201106235109.7066-2-peter.maydell@linaro.org>
Signed-off-by: Laurent Vivier <laurent@vivier.eu>
---
 hw/m68k/Kconfig | 1 +
 1 file changed, 1 insertion(+)

(limited to 'hw/m68k/Kconfig')

diff --git a/hw/m68k/Kconfig b/hw/m68k/Kconfig
index c757e7dfa4..60d7bcfb8f 100644
--- a/hw/m68k/Kconfig
+++ b/hw/m68k/Kconfig
@@ -22,3 +22,4 @@ config Q800
     select ESCC
     select ESP
     select DP8393X
+    select OR_IRQ
-- 
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