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Commit b5b82df6 authored by David Woodhouse's avatar David Woodhouse Committed by Linus Torvalds
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NS16550A: Restore HS settings in EXCR2 on resume 



After a suspend/resume cycle, the UART may have been reset into
low-speed mode -- either because it's actually been reset, or because
the firmware pokes at the old-style divisor registers. If we detected it
as a NS16550A SuperIO chip in the first place and set baud_base to
921600, then we should do so again in the resume path.

This patch adds that code to serial8250_resume_port(), and also makes
serial8250_resume() actually call serial8250_resume_port() for each port
instead of just calling uart_resume_port() directly. And thus fixes
serial port operation after suspend/resume.

It also fixes a bogus comment where we write the EXCR2 register with a
comment saying /* EXCR1 */

Signed-off-by: default avatarDavid Woodhouse <dwmw2@infradead.org>
Acked-by: default avatarAlan Cox <alan@redhat.com>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
parent c97a9e10

drivers/serial/8250.c

+18 −3
Original line number Diff line number Diff line
@@ -894,7 +894,7 @@ static void autoconfig_16550a(struct uart_8250_port *up) 
			quot = serial_dl_read(up);

			quot <<= 3;



			status1 = serial_in(up, 0x04); /* EXCR1 */

			status1 = serial_in(up, 0x04); /* EXCR2 */

			status1 &= ~0xB0; /* Disable LOCK, mask out PRESL[01] */

			status1 |= 0x10;  /* 1.625 divisor for baud_base --> 921600 */

			serial_outp(up, 0x04, status1);
@@ -2617,7 +2617,22 @@ void serial8250_suspend_port(int line) 
 */

void serial8250_resume_port(int line)

{

	uart_resume_port(&serial8250_reg, &serial8250_ports[line].port);

	struct uart_8250_port *up = &serial8250_ports[line];



	if (up->capabilities & UART_NATSEMI) {

		unsigned char tmp;



		/* Ensure it's still in high speed mode */

		serial_outp(up, UART_LCR, 0xE0);



		tmp = serial_in(up, 0x04); /* EXCR2 */

		tmp &= ~0xB0; /* Disable LOCK, mask out PRESL[01] */

		tmp |= 0x10;  /* 1.625 divisor for baud_base --> 921600 */

		serial_outp(up, 0x04, tmp);



		serial_outp(up, UART_LCR, 0);

	}

	uart_resume_port(&serial8250_reg, &up->port);

}



/*
@@ -2694,7 +2709,7 @@ static int serial8250_resume(struct platform_device *dev) 
		struct uart_8250_port *up = &serial8250_ports[i];



		if (up->port.type != PORT_UNKNOWN && up->port.dev == &dev->dev)

			uart_resume_port(&serial8250_reg, &up->port);

			serial8250_resume_port(i);

	}



	return 0;