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NS16550A: Restore HS settings in EXCR2 on resume

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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: David Woodhouse <dwmw2@infradead.org>
Acked-by: Alan Cox <alan@redhat.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This commit is contained in:
David Woodhouse 2007-05-17 14:27:39 +08:00 • committed by Linus Torvalds
commit b5b82df6f4
1 changed files with 18 additions and 3 deletions
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21
drivers/serial/8250.c
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@ -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;