From: Alexey Pelykh <alexey.pelykh@xxxxxxxxx>
Original configuration of Rx FIFO threshold contained an error
that resulted Rx threshold to be effectively set to 1 character
instead of 16 characters, as noted in comments.
Checking LSR to contain UART_LSR_THRE bit set caused issue when
not all UART_IER_THRI interrupts have been properly handled.
This caused gap in Tx data, visible on high baud rates using
oscilloscope.
Setting OMAP_UART_SCR_TX_EMPTY bit in SCR caused UART_IER_THRI
interrupt to be raised only when Tx FIFO and Tx shift registers
are empty.
Signed-off-by: Alexey Pelykh <alexey.pelykh@xxxxxxxxx>
diff --git a/drivers/tty/serial/omap-serial.c b/drivers/tty/serial/omap-serial.c
index 57d6b29..fad46a2 100644
--- a/drivers/tty/serial/omap-serial.c
+++ b/drivers/tty/serial/omap-serial.c
@@ -59,6 +59,7 @@
/* SCR register bitmasks */
#define OMAP_UART_SCR_RX_TRIG_GRANU1_MASK (1 << 7)
+#define OMAP_UART_SCR_TX_TRIG_GRANU1_MASK (1 << 6)
#define OMAP_UART_SCR_TX_EMPTY (1 << 3)
/* FCR register bitmasks */
@@ -302,9 +321,6 @@ static void transmit_chars(struct uart_omap_port *up, unsigned int lsr)
struct circ_buf *xmit = &up->port.state->xmit;
int count;
- if (!(lsr & UART_LSR_THRE))
- return;
-
if (up->port.x_char) {
serial_out(up, UART_TX, up->port.x_char);
up->port.icount.tx++;
@@ -845,7 +861,7 @@ serial_omap_set_termios(struct uart_port *port, struct ktermios *termios,
serial_out(up, UART_IER, up->ier);
serial_out(up, UART_LCR, cval); /* reset DLAB */
up->lcr = cval;
- up->scr = OMAP_UART_SCR_TX_EMPTY;
+ up->scr = 0;
/* FIFOs and DMA Settings */
@@ -869,8 +885,6 @@ serial_omap_set_termios(struct uart_port *port, struct ktermios *termios,
serial_out(up, UART_MCR, up->mcr | UART_MCR_TCRTLR);
/* FIFO ENABLE, DMA MODE */
- up->scr |= OMAP_UART_SCR_RX_TRIG_GRANU1_MASK;
-
/* Set receive FIFO threshold to 16 characters and
* transmit FIFO threshold to 16 spaces
*/
--
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