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Revert "drivers: serial: ns16550: Fix TX IRQ not triggered...

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...when FIFO is empty"

This reverts commit 47e43d552e.

This is breaking sample.sensor.shell.pytest where characters
are either missing or repeated when printing to the console.

Originally this is just for RISC-V with PLIC interrupt
controller. That was made more general to avoid having arch
specific code in a generic driver. And now it is breaking
on non-RISC-V platforms. Note that the QEMU RISC-V boards
all have PLIC as interrupt controller and are passing sensor
shell pytest without this workaround. So this does not seem
to be an issue with PLIC and NS16550.  So revert the commit
for now.

Fixes #92187

Signed-off-by: Daniel Leung <daniel.leung@intel.com>
This commit is contained in:
Daniel Leung 2025-06-25 09:56:19 -07:00 committed by Benjamin Cabé
parent d41716f63c
commit 12ed0528b3
2 changed files with 0 additions and 60 deletions
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11
drivers/serial/Kconfig.ns16550
View File

@ -103,17 +103,6 @@ config UART_NS16550_WA_ISR_REENABLE_INTERRUPT
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.
config UART_NS16550_WA_TX_FIFO_EMPTY_INTERRUPT
bool "Callback directly when the TX FIFO is already empty"
default y if SHELL_BACKEND_SERIAL
depends on UART_INTERRUPT_DRIVEN
help
When calling uart_ns16550_irq_tx_enable() to wait for the TX FIFO
ready interrupt, but this interrupt will only be triggered if the
current state is not empty. Therefore, if the current state is
empty, you need to solve this problem by calling the callback
function directly.
endmenu
endif # UART_NS16550

49
drivers/serial/uart_ns16550.c
View File

@ -369,10 +369,6 @@ struct uart_ns16550_dev_data {
void *cb_data; /**< Callback function arg */
#endif
#ifdef CONFIG_UART_NS16550_WA_TX_FIFO_EMPTY_INTERRUPT
uint8_t sw_tx_irq; /**< software tx ready flag */
#endif
#if UART_NS16550_DLF_ENABLED
uint8_t dlf; /**< DLF value */
#endif
@ -937,10 +933,6 @@ static void uart_ns16550_poll_out(const struct device *dev,
ns16550_outbyte(dev_cfg, THR(dev), c);
#ifdef CONFIG_UART_NS16550_WA_TX_FIFO_EMPTY_INTERRUPT
data->sw_tx_irq = 0; /**< clean up */
#endif
k_spin_unlock(&data->lock, key);
}
@ -988,12 +980,6 @@ static int uart_ns16550_fifo_fill(const struct device *dev,
ns16550_outbyte(dev_cfg, THR(dev), tx_data[i]);
}
#ifdef CONFIG_UART_NS16550_WA_TX_FIFO_EMPTY_INTERRUPT
if (i != 0) {
data->sw_tx_irq = 0; /**< clean up */
}
#endif
k_spin_unlock(&data->lock, key);
return i;
@ -1056,26 +1042,6 @@ static void uart_ns16550_irq_tx_enable(const struct device *dev)
#endif
ns16550_outbyte(dev_cfg, IER(dev), ns16550_inbyte(dev_cfg, IER(dev)) | IER_TBE);
#ifdef CONFIG_UART_NS16550_WA_TX_FIFO_EMPTY_INTERRUPT
if (ns16550_inbyte(dev_cfg, LSR(dev)) & LSR_THRE) {
k_spin_unlock(&data->lock, key);
/*
* The TX FIFO ready interrupt will be triggered if only if
* when the pre-state is not empty. Thus, if the pre-state is
* already empty, try to call the callback routine directly
* to resolve it.
*/
int irq_lock_key = arch_irq_lock();
if (data->cb && (ns16550_inbyte(dev_cfg, LSR(dev)) & LSR_THRE)) {
data->sw_tx_irq = 1; /**< set tx ready */
data->cb(dev, data->cb_data);
}
arch_irq_unlock(irq_lock_key);
return;
}
#endif
k_spin_unlock(&data->lock, key);
}
@ -1090,10 +1056,6 @@ static void uart_ns16550_irq_tx_disable(const struct device *dev)
const struct uart_ns16550_dev_config * const dev_cfg = dev->config;
k_spinlock_key_t key = k_spin_lock(&data->lock);
#ifdef CONFIG_UART_NS16550_WA_TX_FIFO_EMPTY_INTERRUPT
data->sw_tx_irq = 0; /**< clean up */
#endif
ns16550_outbyte(dev_cfg, IER(dev),
ns16550_inbyte(dev_cfg, IER(dev)) & (~IER_TBE));
@ -1134,17 +1096,6 @@ static int uart_ns16550_irq_tx_ready(const struct device *dev)
int ret = ((IIRC(dev) & IIR_ID) == IIR_THRE) ? 1 : 0;
#ifdef CONFIG_UART_NS16550_WA_TX_FIFO_EMPTY_INTERRUPT
if (ret == 0 && data->sw_tx_irq) {
/**< replace resoult when there is a software solution */
const struct uart_ns16550_dev_config * const dev_cfg = dev->config;
if (ns16550_inbyte(dev_cfg, IER(dev)) & IER_TBE) {
ret = 1;
}
}
#endif
k_spin_unlock(&data->lock, key);
return ret;