[PATCH v3 5/6] serial: Call flush() before changing baudrate

Pali Rohár pali at kernel.org
Mon Sep 5 11:31:20 CEST 2022


Changing baudrate is a sensitive operation. To ensure that U-Boot messages
printed before changing baudrate are not lost, call new U-Boot console
flush() function.

Signed-off-by: Pali Rohár <pali at kernel.org>
---
Changes in v3:
* Remove support from serial.c
* Fix commit message
---
 cmd/load.c                     | 5 +++++
 drivers/serial/serial-uclass.c | 1 +
 2 files changed, 6 insertions(+)

diff --git a/cmd/load.c b/cmd/load.c
index e44ae0d56b75..5c4f34781d45 100644
--- a/cmd/load.c
+++ b/cmd/load.c
@@ -83,6 +83,7 @@ static int do_load_serial(struct cmd_tbl *cmdtp, int flag, int argc,
 		printf("## Switch baudrate to %d bps and press ENTER ...\n",
 			load_baudrate);
 		udelay(50000);
+		flush();
 		gd->baudrate = load_baudrate;
 		serial_setbrg();
 		udelay(50000);
@@ -126,6 +127,7 @@ static int do_load_serial(struct cmd_tbl *cmdtp, int flag, int argc,
 		printf("## Switch baudrate to %d bps and press ESC ...\n",
 			current_baudrate);
 		udelay(50000);
+		flush();
 		gd->baudrate = current_baudrate;
 		serial_setbrg();
 		udelay(50000);
@@ -317,6 +319,7 @@ int do_save_serial(struct cmd_tbl *cmdtp, int flag, int argc,
 		printf("## Switch baudrate to %d bps and press ESC ...\n",
 			(int)current_baudrate);
 		udelay(50000);
+		flush();
 		gd->baudrate = current_baudrate;
 		serial_setbrg();
 		udelay(50000);
@@ -471,6 +474,7 @@ static int do_load_serial_bin(struct cmd_tbl *cmdtp, int flag, int argc,
 		printf("## Switch baudrate to %d bps and press ENTER ...\n",
 			load_baudrate);
 		udelay(50000);
+		flush();
 		gd->baudrate = load_baudrate;
 		serial_setbrg();
 		udelay(50000);
@@ -533,6 +537,7 @@ static int do_load_serial_bin(struct cmd_tbl *cmdtp, int flag, int argc,
 		printf("## Switch baudrate to %d bps and press ESC ...\n",
 			current_baudrate);
 		udelay(50000);
+		flush();
 		gd->baudrate = current_baudrate;
 		serial_setbrg();
 		udelay(50000);
diff --git a/drivers/serial/serial-uclass.c b/drivers/serial/serial-uclass.c
index f028da0900cd..04b753c229ab 100644
--- a/drivers/serial/serial-uclass.c
+++ b/drivers/serial/serial-uclass.c
@@ -476,6 +476,7 @@ static int on_baudrate(const char *name, const char *value, enum env_op op,
 			printf("## Switch baudrate to %d bps and press ENTER ...\n",
 			       baudrate);
 			udelay(50000);
+			flush();
 		}
 
 		gd->baudrate = baudrate;
-- 
2.20.1



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