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 <[email protected]>
diff --git a/drivers/serial/8250.c b/drivers/serial/8250.c
index 48e259a..c84dab0 100644
--- a/drivers/serial/8250.c
+++ b/drivers/serial/8250.c
@@ -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;
--
dwmw2
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