linux-kernel - [PATCH v3] use callbacks to access UART_DLL/UART

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Date:	Fri, 18 Dec 2015 17:40:05 +0100
From:	Sebastian Frias <sf84@...oste.net>
To:	Peter Hurley <peter@...leysoftware.com>
CC:	Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
	Måns Rullgård 
	<mans@...sr.com>, linux-serial@...r.kernel.org,
	LKML <linux-kernel@...r.kernel.org>, Mason <slash.tmp@...e.fr>,
	Jon Anders Haugum <jonah@...gav.ntnu.no>
Subject: [PATCH v3] use callbacks to access UART_DLL/UART_DLM

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@...oste.net>
---
  drivers/tty/serial/8250/8250_port.c |   18 ++++++------------
  1 file changed, 6 insertions(+), 12 deletions(-)

diff --git a/drivers/tty/serial/8250/8250_port.c 
b/drivers/tty/serial/8250/8250_port.c
index 52d82d2..56ccbce 100644
--- a/drivers/tty/serial/8250/8250_port.c
+++ b/drivers/tty/serial/8250/8250_port.c
@@ -713,22 +713,16 @@ 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;
-- 
1.7.10.4
--
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