From: Dmitry Fink Date: Mon, 8 Jul 2013 10:04:44 +0000 (+0300) Subject: OMAP: UART: Keep the TX fifo full when possible X-Git-Url: http://git.lede-project.org./?a=commitdiff_plain;h=c4415084218c68c5ee2fc583431e89a78d896b19;p=openwrt%2Fstaging%2Fblogic.git OMAP: UART: Keep the TX fifo full when possible Current logic results in interrupt storm since the fifo is constantly below the threshold level. Change the logic to fill all the available spaces in the fifo as long as we have data to minimize the possibilty of underflow and elimiate excessive interrupts. Signed-off-by: Dmitry Fink Signed-off-by: Alexander Savchenko Signed-off-by: Greg Kroah-Hartman --- diff --git a/drivers/tty/serial/omap-serial.c b/drivers/tty/serial/omap-serial.c index 33c758e09d86..9271a1dceec3 100644 --- a/drivers/tty/serial/omap-serial.c +++ b/drivers/tty/serial/omap-serial.c @@ -315,7 +315,8 @@ static void transmit_chars(struct uart_omap_port *up, unsigned int lsr) serial_omap_stop_tx(&up->port); return; } - count = up->port.fifosize / 4; + count = up->port.fifosize - + (serial_in(up, UART_OMAP_TXFIFO_LVL) & 0xFF); do { serial_out(up, UART_TX, xmit->buf[xmit->tail]); xmit->tail = (xmit->tail + 1) & (UART_XMIT_SIZE - 1); diff --git a/include/uapi/linux/serial_reg.h b/include/uapi/linux/serial_reg.h index e6322605b138..97c26beae605 100644 --- a/include/uapi/linux/serial_reg.h +++ b/include/uapi/linux/serial_reg.h @@ -366,6 +366,7 @@ #define UART_OMAP_MDR1_FIR_MODE 0x05 /* FIR mode */ #define UART_OMAP_MDR1_CIR_MODE 0x06 /* CIR mode */ #define UART_OMAP_MDR1_DISABLE 0x07 /* Disable (default state) */ +#define UART_OMAP_TXFIFO_LVL 0x1A /* TX FIFO fullness */ /* * These are definitions for the Exar XR17V35X and XR17(C|D)15X