CONFIG_UART_NS16550_WA_ISR_REENABLE_INTERRUPT

Re-enable interrupts by toggling IER at end of ISR

Type: bool

Help

In some configurations (e.g. edge interrupt triggers),
an interruptible event occurs during ISR and the host interrupt
controller does not see the new event due to IIR is constantly
asserting interrupts. For example, the callback handles RX and
then TX. If another character comes in before end of TX processing
(TX interrupt still asserts while raising RX interrupt), the host
interrupt controller may not see this new event. So if needed,
the IER is being toggled to re-assert interrupts at the end of ISR
to nudge the host interrupt controller to fire the ISR again.

Direct dependencies

(UART_NS16550 && SOC_SERIES_RISCV32_IT8XXX2) || (UART_NS16550 && SOC_SERIES_RISCV32_IT8XXX2) || (UART_INTERRUPT_DRIVEN && UART_NS16550 && SERIAL)

(Includes any dependencies from ifs and menus.)

Defaults

• y

• y

Kconfig definitions

At <Zephyr>/soc/riscv/riscv-ite/it8xxx2/Kconfig.defconfig.series:32

Included via <Zephyr>/Kconfig:8 → <Zephyr>/Kconfig.zephyr:25 → <nRF>/doc/_build/kconfig/Kconfig.soc.defconfig:1 → <Zephyr>/soc/riscv/riscv-ite/Kconfig.defconfig:4

Menu path: (Top)

config UART_NS16550_WA_ISR_REENABLE_INTERRUPT
    bool
    default y
    depends on UART_NS16550 && SOC_SERIES_RISCV32_IT8XXX2

---

At <Zephyr>/soc/riscv/riscv-ite/it8xxx2/Kconfig.defconfig.series:32

Included via <Zephyr>/Kconfig:8 → <Zephyr>/Kconfig.zephyr:27 → <Zephyr>/soc/riscv/riscv-ite/Kconfig.defconfig:4

Menu path: (Top)

config UART_NS16550_WA_ISR_REENABLE_INTERRUPT
    bool
    default y
    depends on UART_NS16550 && SOC_SERIES_RISCV32_IT8XXX2

---

At <Zephyr>/drivers/serial/Kconfig.ns16550:46

Included via <Zephyr>/Kconfig:8 → <Zephyr>/Kconfig.zephyr:42 → <Zephyr>/drivers/Kconfig:26 → <Zephyr>/drivers/serial/Kconfig:104

Menu path: (Top) → Device Drivers → Serial Drivers → NS16550 serial driver → NS16550 Workarounds

config UART_NS16550_WA_ISR_REENABLE_INTERRUPT
    bool "Re-enable interrupts by toggling IER at end of ISR"
    depends on UART_INTERRUPT_DRIVEN && UART_NS16550 && SERIAL
    help
      In some configurations (e.g. edge interrupt triggers),
      an interruptible event occurs during ISR and the host interrupt
      controller does not see the new event due to IIR is constantly
      asserting interrupts. For example, the callback handles RX and
      then TX. If another character comes in before end of TX processing
      (TX interrupt still asserts while raising RX interrupt), the host
      interrupt controller may not see this new event. So if needed,
      the IER is being toggled to re-assert interrupts at the end of ISR
      to nudge the host interrupt controller to fire the ISR again.

(The ‘depends on’ condition includes propagated dependencies from ifs and menus.)