3.19.8-ckt18 -stable review patch. If anyone has any objections, please let me
know.
---8<------------------------------------------------------------
From: Sebastian Frias <s...@laposte.net>
commit 0b41ce991052022c030fd868e03877700220b090 upstream.
Some UART HW has a single register combining UART_DLL/UART_DLM
(this was probably forgotten in the change that introduced the
callbacks, commit b32b19b8ffc05cbd3bf91c65e205f6a912ca15d9)
Fixes: b32b19b8ffc0 ("[SERIAL] 8250: set divisor register correctly ...")
Signed-off-by: Sebastian Frias <s...@laposte.net>
Reviewed-by: Peter Hurley <pe...@hurleysoftware.com>
Signed-off-by: Greg Kroah-Hartman <gre...@linuxfoundation.org>
[ kamal: backport to 4.2-stable: applies to 8250_core.c ]
Signed-off-by: Kamal Mostafa <ka...@canonical.com>
---
drivers/tty/serial/8250/8250_core.c | 18 ++++++------------
1 file changed, 6 insertions(+), 12 deletions(-)
diff --git a/drivers/tty/serial/8250/8250_core.c
b/drivers/tty/serial/8250/8250_core.c
index bacc588..2f2a9bb 100644
--- a/drivers/tty/serial/8250/8250_core.c
+++ b/drivers/tty/serial/8250/8250_core.c
@@ -751,22 +751,16 @@ static int size_fifo(struct uart_8250_port *up)
*/
static unsigned int autoconfig_read_divisor_id(struct uart_8250_port *p)
{
- unsigned char old_dll, old_dlm, old_lcr;
- unsigned int id;
+ unsigned char old_lcr;
+ unsigned int id, old_dl;
old_lcr = serial_in(p, UART_LCR);
serial_out(p, UART_LCR, UART_LCR_CONF_MODE_A);
+ old_dl = serial_dl_read(p);
+ serial_dl_write(p, 0);
+ id = serial_dl_read(p);
+ serial_dl_write(p, old_dl);
- old_dll = serial_in(p, UART_DLL);
- old_dlm = serial_in(p, UART_DLM);
-
- serial_out(p, UART_DLL, 0);
- serial_out(p, UART_DLM, 0);
-
- id = serial_in(p, UART_DLL) | serial_in(p, UART_DLM) << 8;
-
- serial_out(p, UART_DLL, old_dll);
- serial_out(p, UART_DLM, old_dlm);
serial_out(p, UART_LCR, old_lcr);
return id;
--
2.7.4
