From: Peter Maydell <peter.mayd...@linaro.org> 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.mayd...@linaro.org> Reviewed-by: Philippe Mathieu-Daudé <f4...@amsat.org> Reviewed-by: Laurent Vivier <laur...@vivier.eu> Message-Id: <20201106235109.7066-2-peter.mayd...@linaro.org> Signed-off-by: Laurent Vivier <laur...@vivier.eu> --- hw/m68k/q800.c | 12 ++++++++++-- hw/m68k/Kconfig | 1 + 2 files changed, 11 insertions(+), 2 deletions(-) diff --git a/hw/m68k/q800.c b/hw/m68k/q800.c index 4db2b9bbc7b4..f9a2be776eb0 100644 --- a/hw/m68k/q800.c +++ b/hw/m68k/q800.c @@ -29,6 +29,7 @@ #include "hw/hw.h" #include "hw/boards.h" #include "hw/irq.h" +#include "hw/or-irq.h" #include "elf.h" #include "hw/loader.h" #include "ui/console.h" @@ -173,6 +174,7 @@ static void q800_init(MachineState *machine) CPUState *cs; DeviceState *dev; DeviceState *via_dev; + DeviceState *escc_orgate; SysBusESPState *sysbus_esp; ESPState *esp; SysBusDevice *sysbus; @@ -285,8 +287,14 @@ static void q800_init(MachineState *machine) qdev_prop_set_uint32(dev, "chnAtype", 0); sysbus = SYS_BUS_DEVICE(dev); sysbus_realize_and_unref(sysbus, &error_fatal); - sysbus_connect_irq(sysbus, 0, pic[3]); - sysbus_connect_irq(sysbus, 1, pic[3]); + + /* Logically OR both its IRQs together */ + escc_orgate = DEVICE(object_new(TYPE_OR_IRQ)); + object_property_set_int(OBJECT(escc_orgate), "num-lines", 2, &error_fatal); + qdev_realize_and_unref(escc_orgate, NULL, &error_fatal); + sysbus_connect_irq(sysbus, 0, qdev_get_gpio_in(escc_orgate, 0)); + sysbus_connect_irq(sysbus, 1, qdev_get_gpio_in(escc_orgate, 1)); + qdev_connect_gpio_out(DEVICE(escc_orgate), 0, pic[3]); sysbus_mmio_map(sysbus, 0, SCC_BASE); /* SCSI */ diff --git a/hw/m68k/Kconfig b/hw/m68k/Kconfig index c757e7dfa48b..60d7bcfb8f2b 100644 --- a/hw/m68k/Kconfig +++ b/hw/m68k/Kconfig @@ -22,3 +22,4 @@ config Q800 select ESCC select ESP select DP8393X + select OR_IRQ -- 2.29.2