Hello Tobias, On Mon, Dec 18, 2017 at 10:52:52AM +0100, Tobias Klauser wrote: > On 2017-12-18 at 10:41:48 +0100, Uwe Kleine-König <u.kleine-koenig@xxxxxxxxxxxxxx> wrote: > > The UART can be operated without an irq. In this case a timer is setup > > that regularily calls altera_uart_interrupt(). The receiving part > > depends on pp->imr having the bit ALTERA_UART_STATUS_RRDY_MSK set, > > otherwise altera_uart_rx_chars() is never called. So ensure that the bit > > gets set (disguised as ALTERA_UART_CONTROL_RRDY_MSK) by not returning > > early from altera_uart_startup() if port->irq is 0. > > While the above is true, I don't think your patch is entriely correct. > Now we would write ALTERA_UART_STATUS_RRDY_MSK to the control register > which would enable read-ready interrupts even in IRQ-less mode (see > Table 69 in [1]). > > [1] https://www.altera.com/content/dam/altera-www/global/en_US/pdfs/literature/ug/ug_embedded_ip.pdf Where does it hurt that an irq is enabled in irq-less mode? Best regards Uwe -- Pengutronix e.K. | Uwe Kleine-König | Industrial Linux Solutions | http://www.pengutronix.de/ | -- To unsubscribe from this list: send the line "unsubscribe linux-serial" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
