Commit a194597c authored by Jiri Slaby (SUSE)'s avatar Jiri Slaby (SUSE) Committed by Greg Kroah-Hartman
Browse files

serial: 8250: extract serial8250_THRE_test() 



serial8250_do_startup() contains a stand-alone code for probing THRE.
Furthermore, the code block is conditional (port->irq and test for
UPF_NO_THRE_TEST).

Move this code to a separate function. The conditional can be evaluated
easier there -- by a simple return in the beginning. So the indentation
level lowers and the code is overall more readable now.

Signed-off-by: default avatar"Jiri Slaby (SUSE)" <jirislaby@kernel.org>
Link: https://lore.kernel.org/r/20250611100319.186924-16-jirislaby@kernel.org


Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
parent cc852682

drivers/tty/serial/8250/8250_port.c

+49 −43
Original line number Diff line number Diff line
@@ -2199,6 +2199,54 @@ static void serial8250_set_TRG_levels(struct uart_port *port) 
	}

}



static void serial8250_THRE_test(struct uart_port *port)

{

	struct uart_8250_port *up = up_to_u8250p(port);

	unsigned long flags;

	bool iir_noint1, iir_noint2;



	if (!port->irq)

		return;



	if (up->port.flags & UPF_NO_THRE_TEST)

		return;



	if (port->irqflags & IRQF_SHARED)

		disable_irq_nosync(port->irq);



	/*

	 * Test for UARTs that do not reassert THRE when the transmitter is idle and the interrupt

	 * has already been cleared.  Real 16550s should always reassert this interrupt whenever the

	 * transmitter is idle and the interrupt is enabled.  Delays are necessary to allow register

	 * changes to become visible.

	 *

	 * Synchronize UART_IER access against the console.

	 */

	uart_port_lock_irqsave(port, &flags);



	wait_for_xmitr(up, UART_LSR_THRE);

	serial_port_out_sync(port, UART_IER, UART_IER_THRI);

	udelay(1); /* allow THRE to set */

	iir_noint1 = serial_port_in(port, UART_IIR) & UART_IIR_NO_INT;

	serial_port_out(port, UART_IER, 0);

	serial_port_out_sync(port, UART_IER, UART_IER_THRI);

	udelay(1); /* allow a working UART time to re-assert THRE */

	iir_noint2 = serial_port_in(port, UART_IIR) & UART_IIR_NO_INT;

	serial_port_out(port, UART_IER, 0);



	uart_port_unlock_irqrestore(port, flags);



	if (port->irqflags & IRQF_SHARED)

		enable_irq(port->irq);



	/*

	 * If the interrupt is not reasserted, or we otherwise don't trust the iir, setup a timer to

	 * kick the UART on a regular basis.

	 */

	if ((!iir_noint1 && iir_noint2) || up->port.flags & UPF_BUG_THRE)

		up->bugs |= UART_BUG_THRE;

}



int serial8250_do_startup(struct uart_port *port)

{

	struct uart_8250_port *up = up_to_u8250p(port);
@@ -2258,49 +2306,7 @@ int serial8250_do_startup(struct uart_port *port) 
	if (retval)

		goto out;



	if (port->irq && !(up->port.flags & UPF_NO_THRE_TEST)) {

		unsigned char iir1;



		if (port->irqflags & IRQF_SHARED)

			disable_irq_nosync(port->irq);



		/*

		 * Test for UARTs that do not reassert THRE when the

		 * transmitter is idle and the interrupt has already

		 * been cleared.  Real 16550s should always reassert

		 * this interrupt whenever the transmitter is idle and

		 * the interrupt is enabled.  Delays are necessary to

		 * allow register changes to become visible.

		 *

		 * Synchronize UART_IER access against the console.

		 */

		uart_port_lock_irqsave(port, &flags);



		wait_for_xmitr(up, UART_LSR_THRE);

		serial_port_out_sync(port, UART_IER, UART_IER_THRI);

		udelay(1); /* allow THRE to set */

		iir1 = serial_port_in(port, UART_IIR);

		serial_port_out(port, UART_IER, 0);

		serial_port_out_sync(port, UART_IER, UART_IER_THRI);

		udelay(1); /* allow a working UART time to re-assert THRE */

		iir = serial_port_in(port, UART_IIR);

		serial_port_out(port, UART_IER, 0);



		uart_port_unlock_irqrestore(port, flags);



		if (port->irqflags & IRQF_SHARED)

			enable_irq(port->irq);



		/*

		 * If the interrupt is not reasserted, or we otherwise

		 * don't trust the iir, setup a timer to kick the UART

		 * on a regular basis.

		 */

		if ((!(iir1 & UART_IIR_NO_INT) && (iir & UART_IIR_NO_INT)) ||

		    up->port.flags & UPF_BUG_THRE) {

			up->bugs |= UART_BUG_THRE;

		}

	}

	serial8250_THRE_test(port);



	up->ops->setup_timer(up);