Commit ff446fb8 authored by Jiri Slaby (SUSE)'s avatar Jiri Slaby (SUSE) Committed by Greg Kroah-Hartman
Browse files

serial: 8250: extract serial8250_iir_txen_test() 



After commit 79515869 ("serial: 8250: extract
serial8250_initialize()"), split serial8250_initialize() even more --
the TX enable test part of this code can be separated into
serial8250_iir_txen_test().

Signed-off-by: default avatar"Jiri Slaby (SUSE)" <jirislaby@kernel.org>
Suggested-by: default avatarIlpo Järvinen <ilpo.jarvinen@linux.intel.com>
Reviewed-by: default avatarIlpo Järvinen <ilpo.jarvinen@linux.intel.com>
Reviewed-by: default avatarAndy Shevchenko <andriy.shevchenko@linux.intel.com>
Link: https://lore.kernel.org/r/20250624080641.509959-3-jirislaby@kernel.org


Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
parent 7bdf59c7

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

+28 −21
Original line number Diff line number Diff line
@@ -2230,16 +2230,19 @@ static void serial8250_init_mctrl(struct uart_port *port) 
	serial8250_set_mctrl(port, port->mctrl);

}



static void serial8250_initialize(struct uart_port *port)

static void serial8250_iir_txen_test(struct uart_port *port)

{

	struct uart_8250_port *up = up_to_u8250p(port);

	unsigned long flags;

	bool lsr_TEMT, iir_NOINT;



	serial_port_out(port, UART_LCR, UART_LCR_WLEN8);

	if (port->quirks & UPQ_NO_TXEN_TEST)

		return;



	uart_port_lock_irqsave(port, &flags);

	serial8250_init_mctrl(port);

	/* Do a quick test to see if we receive an interrupt when we enable the TX irq. */

	serial_port_out(port, UART_IER, UART_IER_THRI);

	lsr_TEMT = serial_port_in(port, UART_LSR) & UART_LSR_TEMT;

	iir_NOINT = serial_port_in(port, UART_IIR) & UART_IIR_NO_INT;

	serial_port_out(port, UART_IER, 0);



	/*

	 * Serial over Lan (SoL) hack:
@@ -2247,26 +2250,30 @@ static void serial8250_initialize(struct uart_port *port) 
	 * Lan.  Those chips take a longer time than a normal serial device to signalize that a

	 * transmission data was queued. Due to that, the above test generally fails. One solution

	 * would be to delay the reading of iir. However, this is not reliable, since the timeout is

	 * variable. So, let's just don't test if we receive TX irq.  This way, we'll never enable

	 * UART_BUG_TXEN.

	 * variable. So, in case of UPQ_NO_TXEN_TEST, let's just don't test if we receive TX irq.

	 * This way, we'll never enable UART_BUG_TXEN.

	 */

	if (!(port->quirks & UPQ_NO_TXEN_TEST)) {

		/* Do a quick test to see if we receive an interrupt when we enable the TX irq. */

		serial_port_out(port, UART_IER, UART_IER_THRI);

		lsr_TEMT = serial_port_in(port, UART_LSR) & UART_LSR_TEMT;

		iir_NOINT = serial_port_in(port, UART_IIR) & UART_IIR_NO_INT;

		serial_port_out(port, UART_IER, 0);



	if (lsr_TEMT && iir_NOINT) {

		if (!(up->bugs & UART_BUG_TXEN)) {

			up->bugs |= UART_BUG_TXEN;

			dev_dbg(port->dev, "enabling bad tx status workarounds\n");

		}

		} else {

			up->bugs &= ~UART_BUG_TXEN;

		return;

	}



	/* FIXME: why is this needed? */

	up->bugs &= ~UART_BUG_TXEN;

}



static void serial8250_initialize(struct uart_port *port)

{

	unsigned long flags;



	serial_port_out(port, UART_LCR, UART_LCR_WLEN8);



	uart_port_lock_irqsave(port, &flags);

	serial8250_init_mctrl(port);

	serial8250_iir_txen_test(port);

	uart_port_unlock_irqrestore(port, flags);

}