From a68555f48d06b4c8d55f7e4ca208805bec3d5512 Mon Sep 17 00:00:00 2001 From: Kevin O'Connor Date: Sat, 9 Jul 2011 20:22:21 -0400 Subject: 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 Reviewed-on: http://review.coreboot.org/90 Reviewed-by: Stefan Reinauer Tested-by: build bot (Jenkins) Reviewed-by: Rudolf Marek Reviewed-by: Sven Schnelle --- src/console/uart8250_console.c | 6 ++++++ src/console/uart8250mem_console.c | 6 ++++++ 2 files changed, 12 insertions(+) (limited to 'src/console') diff --git a/src/console/uart8250_console.c b/src/console/uart8250_console.c index 4799ca66e5..330ed684f7 100644 --- a/src/console/uart8250_console.c +++ b/src/console/uart8250_console.c @@ -31,6 +31,11 @@ static void ttyS0_tx_byte(unsigned char data) uart8250_tx_byte(CONFIG_TTYS0_BASE, data); } +static void ttyS0_tx_flush(void) +{ + uart8250_tx_flush(CONFIG_TTYS0_BASE); +} + static unsigned char ttyS0_rx_byte(void) { return uart8250_rx_byte(CONFIG_TTYS0_BASE); @@ -44,6 +49,7 @@ static int ttyS0_tst_byte(void) static const struct console_driver uart8250_console __console = { .init = ttyS0_init, .tx_byte = ttyS0_tx_byte, + .tx_flush = ttyS0_tx_flush, .rx_byte = ttyS0_rx_byte, .tst_byte = ttyS0_tst_byte, }; diff --git a/src/console/uart8250mem_console.c b/src/console/uart8250mem_console.c index a6968ddc4b..e622ad090c 100644 --- a/src/console/uart8250mem_console.c +++ b/src/console/uart8250mem_console.c @@ -36,6 +36,11 @@ static void uartmem_tx_byte(unsigned char data) uart8250_mem_tx_byte(uart_bar, data); } +static void uartmem_tx_flush(void) +{ + uart8250_mem_tx_flush(uart_bar); +} + static unsigned char uartmem_rx_byte(void) { if (!uart_bar) @@ -55,6 +60,7 @@ static int uartmem_tst_byte(void) static const struct console_driver uart8250mem_console __console = { .init = uartmem_init, .tx_byte = uartmem_tx_byte, + .tx_flush = uartmem_tx_flush, .rx_byte = uartmem_rx_byte, .tst_byte = uartmem_tst_byte, }; -- cgit v1.2.3