Fixes: 6bf4e42f1d19de10800f4483b4bb7945aab283cb
Have pericom_do_set_divisor() use the uartclk instead of a hardcoded
value to work with different speed crystals. Tested with 14.7456 and 24
MHz crystals
Have pericom_do_set_divisor always calculate the divisor rather than
call serial8250_do_set_divisor() for rates below baud_base.
Do not write registers or call serial8250_do_set_divisor() if valid
divisors could not be found.
Signed-off-by: Jay Dolan <jay.dolan@xxxxxxxxxxx>
---
drivers/tty/serial/8250/8250_pci.c | 28 ++++++++++++++++------------
1 file changed, 16 insertions(+), 12 deletions(-)
diff --git a/drivers/tty/serial/8250/8250_pci.c b/drivers/tty/serial/8250/8250_pci.c
index 5d43de143f33..aea43683b76d 100644
--- a/drivers/tty/serial/8250/8250_pci.c
+++ b/drivers/tty/serial/8250/8250_pci.c
@@ -1325,28 +1325,32 @@ pericom_do_set_divisor(struct uart_port *port, unsigned int baud,
int scr;
int lcr;
int actual_baud;
- int tolerance;
+ int divisor;
- for (scr = 5 ; scr <= 15 ; scr++) {
- actual_baud = 921600 * 16 / scr;
- tolerance = actual_baud / 50;
+ for (scr = 16 ; scr > 4 ; scr--) {
+ if (baud > (port->uartclk / scr) + (baud/50))
+ continue;
- if ((baud < actual_baud + tolerance) &&
- (baud > actual_baud - tolerance)) {
+ divisor = port->uartclk / scr / baud;
+ if (divisor == 0 ||
+ port->uartclk / scr / divisor - baud > baud/50) {
+ divisor++;
+ }
+
+ if (divisor > 0xffff)
+ continue;
+ actual_baud = port->uartclk / scr / divisor;
+ if (abs(actual_baud - baud) < baud/50) {
lcr = serial_port_in(port, UART_LCR);
serial_port_out(port, UART_LCR, lcr | 0x80);
-
- serial_port_out(port, UART_DLL, 1);
- serial_port_out(port, UART_DLM, 0);
+ serial_port_out(port, UART_DLL, divisor & 0xff);
+ serial_port_out(port, UART_DLM, divisor >> 8 & 0xff);
serial_port_out(port, 2, 16 - scr);
serial_port_out(port, UART_LCR, lcr);
return;
- } else if (baud > actual_baud) {
- break;
}
}
- serial8250_do_set_divisor(port, baud, quot, quot_frac);
}
static int pci_pericom_setup(struct serial_private *priv,
const struct pciserial_board *board,
--
2.25.1
