| From | Kamal Mostafa <> | Subject | [PATCH 4.2.y-ckt 027/218] 8250: use callbacks to access UART_DLL/UART_DLM | Date | Thu, 31 Mar 2016 13:14:00 -0700 |
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4.2.8-ckt7 -stable review patch. If anyone has any objections, please let me know.
---8<------------------------------------------------------------
From: Sebastian Frias <sf84@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 <sf84@laposte.net> Reviewed-by: Peter Hurley <peter@hurleysoftware.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> [ kamal: backport to 4.2-stable: applies to 8250_core.c ] Signed-off-by: Kamal Mostafa <kamal@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 c35d96e..aaa9fac 100644 --- a/drivers/tty/serial/8250/8250_core.c +++ b/drivers/tty/serial/8250/8250_core.c @@ -778,22 +778,16 @@ 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
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