Fall back to polling mode if no interrupt is configured because there is no possibility to connect the interrupt pin. If no interrupt pin is available the driver uses a delayed worker to poll the state of interrupt status registers (IIR). Signed-off-by: Andre Werner <andre.werner@xxxxxxxxxxxxxxxxxxxxx> Link: https://lore.kernel.org/r/20250110073104.1029633-2-andre.werner@xxxxxxxxxxxxxxxxxxxxx Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx> --- V2: - Change warning for polling mode to debug log entry - Correct typo: Resuse -> Reuse - Format define with missing tabs for SC16IS7XX_POLL_PERIOD - Format struct declaration sc16is7xx_one_config with missing tabs for polling and shutdown - Adapt dtbinding with new polling feature V3: - Use suffix with units and drop a comment SC16IS7XX_POLL_PERIOD_MS. Sorry for that miss. - Make Kernel lowercase. V4: - Reword commit messages for better understanding. - Remove 'shutdown' property for canceling delayed worker. - Rename worker function: sc16is7xx_transmission_poll -> sc16is7xx_poll_proc - Unify argument for worker functions: kthread_work *work -> kthread_work *ws V5: - Replace of_property check with IRQ number check to set polling property. This will add support for usage without device tree definitions. Thanks for that advice. - Add blank line es requested. V6: - Use polling mode for IRQ numbers <= 0 which encounter no valid IRQ were found/defined. V7: - Try to improve and unify comments as requested. - Fix typo in commit message: pull -> poll --- drivers/tty/serial/sc16is7xx.c | 10 ++++++---- 1 file changed, 6 insertions(+), 4 deletions(-) diff --git a/drivers/tty/serial/sc16is7xx.c b/drivers/tty/serial/sc16is7xx.c index 7b51cdc274fd..348ddc3103cd 100644 --- a/drivers/tty/serial/sc16is7xx.c +++ b/drivers/tty/serial/sc16is7xx.c @@ -868,10 +868,12 @@ static void sc16is7xx_poll_proc(struct kthread_work *ws) { struct sc16is7xx_port *s = container_of(ws, struct sc16is7xx_port, poll_work.work); - /* Reuse standard IRQ handler. Interrupt ID is unused in this context. */ + /* + * Reuse standard IRQ handler. Interrupt ID is unused in this + * context and set to zero. + */ sc16is7xx_irq(0, s); - /* Setup delay based on SC16IS7XX_POLL_PERIOD_MS */ kthread_queue_delayed_work(&s->kworker, &s->poll_work, msecs_to_jiffies(SC16IS7XX_POLL_PERIOD_MS)); } @@ -1561,7 +1563,7 @@ int sc16is7xx_probe(struct device *dev, const struct sc16is7xx_devtype *devtype, /* Always ask for fixed clock rate from a property. */ device_property_read_u32(dev, "clock-frequency", &uartclk); - s->polling = !!irq; + s->polling = (irq <= 0); if (s->polling) dev_dbg(dev, "No interrupt pin definition, falling back to polling mode\n"); @@ -1694,7 +1696,7 @@ int sc16is7xx_probe(struct device *dev, const struct sc16is7xx_devtype *devtype, #endif if (s->polling) { - /* Initialize kernel thread for polling */ + /* Initialize a kthread work struct that is dedicated to polling */ kthread_init_delayed_work(&s->poll_work, sc16is7xx_poll_proc); return 0; } -- 2.48.0
