tty: serial: OMAP: use a 1-byte RX FIFO threshold in PIO mode

[platform/adaptation/renesas_rcar/renesas_kernel.git] / drivers / tty / serial / omap-serial.c

diff --git a/drivers/tty/serial/omap-serial.c b/drivers/tty/serial/omap-serial.c
index 1c24269..a3f5ea4 100644 (file)
--- a/drivers/tty/serial/omap-serial.c
+++ b/drivers/tty/serial/omap-serial.c
@@ -46,6 +46,13 @@
 
 #define DEFAULT_CLK_SPEED 48000000 /* 48Mhz*/
 
+/* SCR register bitmasks */
+#define OMAP_UART_SCR_RX_TRIG_GRANU1_MASK              (1 << 7)
+
+/* FCR register bitmasks */
+#define OMAP_UART_FCR_RX_FIFO_TRIG_SHIFT               6
+#define OMAP_UART_FCR_RX_FIFO_TRIG_MASK                        (0x3 << 6)
+
 static struct uart_omap_port *ui[OMAP_MAX_HSUART_PORTS];
 
 /* Forward declaration of functions */
@@ -811,14 +818,21 @@ serial_omap_set_termios(struct uart_port *port, struct ktermios *termios,
        up->mcr = serial_in(up, UART_MCR);
        serial_out(up, UART_MCR, up->mcr | UART_MCR_TCRTLR);
        /* FIFO ENABLE, DMA MODE */
-       serial_out(up, UART_FCR, up->fcr);
-       serial_out(up, UART_LCR, UART_LCR_CONF_MODE_B);
+
+       up->scr |= OMAP_UART_SCR_RX_TRIG_GRANU1_MASK;
 
        if (up->use_dma) {
                serial_out(up, UART_TI752_TLR, 0);
-               up->scr |= (UART_FCR_TRIGGER_4 | UART_FCR_TRIGGER_8);
+               up->scr |= UART_FCR_TRIGGER_4;
+       } else {
+               /* Set receive FIFO threshold to 1 byte */
+               up->fcr &= ~OMAP_UART_FCR_RX_FIFO_TRIG_MASK;
+               up->fcr |= (0x1 << OMAP_UART_FCR_RX_FIFO_TRIG_SHIFT);
        }
 
+       serial_out(up, UART_FCR, up->fcr);
+       serial_out(up, UART_LCR, UART_LCR_CONF_MODE_B);
+
        serial_out(up, UART_OMAP_SCR, up->scr);
 
        serial_out(up, UART_EFR, up->efr);