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authorKevin O'Connor <kevin@koconnor.net>2011-07-09 20:22:21 -0400
committerPatrick Georgi <patrick@georgi-clan.de>2011-07-12 11:36:20 +0200
commita68555f48d06b4c8d55f7e4ca208805bec3d5512 (patch)
tree132a21ab3f20d2ca5ce967705d4d92c3c0dbe476 /src/include
parent537cacfa04c9dc56cd608012a73d95ab342d2f81 (diff)
Do full flush on uart8250 only at end of printk.
The previous code does a full flush of the uart after every character. Unfortunately, this can cause transmission delays on some serial ports. This patch changes the code so that it does a flush at the end of every printk instead of at the end of every character. This reduces the time it takes to transmit serial messages (up to 9% on my Asrock e350m1 board). It also makes the transmission time more consistent which is important when performing timing tests via serial transmissions. Change-Id: I6b28488b905da68c6d68d7c517cc743cde567d70 Signed-off-by: Kevin O'Connor <kevin@koconnor.net> Reviewed-on: http://review.coreboot.org/90 Reviewed-by: Stefan Reinauer <stefan.reinauer@coreboot.org> Tested-by: build bot (Jenkins) Reviewed-by: Rudolf Marek <r.marek@assembler.cz> Reviewed-by: Sven Schnelle <svens@stackframe.org>
Diffstat (limited to 'src/include')
-rw-r--r--src/include/uart8250.h2
1 files changed, 2 insertions, 0 deletions
diff --git a/src/include/uart8250.h b/src/include/uart8250.h
index bbf2d8c8a9..4a02179210 100644
--- a/src/include/uart8250.h
+++ b/src/include/uart8250.h
@@ -131,6 +131,7 @@
unsigned char uart8250_rx_byte(unsigned base_port);
int uart8250_can_rx_byte(unsigned base_port);
void uart8250_tx_byte(unsigned base_port, unsigned char data);
+void uart8250_tx_flush(unsigned base_port);
/* Yes it is silly to have three different uart init functions. But we used to
* have three different sets of uart code, so it's an improvement.
@@ -142,6 +143,7 @@ void uart_init(void);
unsigned char uart8250_mem_rx_byte(unsigned base_port);
int uart8250_mem_can_rx_byte(unsigned base_port);
void uart8250_mem_tx_byte(unsigned base_port, unsigned char data);
+void uart8250_mem_tx_flush(unsigned base_port);
void uart8250_mem_init(unsigned base_port, unsigned divisor);
u32 uart_mem_init(void);