lkml.org 
[lkml]   [2013]   [Jul]   [24]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
Patch in this message
/
From
Subject[PATCH 4/4] msm_serial: Send more than 1 character at a time on UARTDM
Date
UARTDM cores have a TX fifo that can accept more than one
character per register write, but the msm_serial driver currently
only supports 1 character mode. Add support for this mode of operation
to speed up the transmit path on DM devices.

Signed-off-by: Stephen Boyd <sboyd@codeaurora.org>
---
drivers/tty/serial/msm_serial.c | 51 ++++++++++++++++++++++++++---------------
1 file changed, 32 insertions(+), 19 deletions(-)

diff --git a/drivers/tty/serial/msm_serial.c b/drivers/tty/serial/msm_serial.c
index cef8f40..97642ec 100644
--- a/drivers/tty/serial/msm_serial.c
+++ b/drivers/tty/serial/msm_serial.c
@@ -195,10 +195,10 @@ static void handle_rx(struct uart_port *port)
tty_flip_buffer_push(tport);
}

-static void reset_dm_count(struct uart_port *port)
+static void reset_dm_count(struct uart_port *port, int count)
{
wait_for_xmitr(port);
- msm_write(port, 1, UARTDM_NCF_TX);
+ msm_write(port, count, UARTDM_NCF_TX);
msm_read(port, UARTDM_NCF_TX);
}

@@ -206,39 +206,52 @@ static void handle_tx(struct uart_port *port)
{
struct circ_buf *xmit = &port->state->xmit;
struct msm_port *msm_port = UART_TO_MSM(port);
- int sent_tx;
+ unsigned int tx_count, num_chars;
+ unsigned int tf_pointer = 0;
+
+ tx_count = uart_circ_chars_pending(xmit);
+ tx_count = min3(tx_count, (unsigned int)UART_XMIT_SIZE - xmit->tail,
+ port->fifosize);

if (port->x_char) {
if (msm_port->is_uartdm)
- reset_dm_count(port);
+ reset_dm_count(port, tx_count + 1);

msm_write(port, port->x_char,
msm_port->is_uartdm ? UARTDM_TF : UART_TF);
port->icount.tx++;
port->x_char = 0;
+ } else if (tx_count && msm_port->is_uartdm) {
+ reset_dm_count(port, tx_count);
}

- if (msm_port->is_uartdm)
- reset_dm_count(port);
+ while (tf_pointer < tx_count) {
+ int i;
+ char buf[4] = { 0 };
+ unsigned int *bf = (unsigned int *)&buf;

- while (msm_read(port, UART_SR) & UART_SR_TX_READY) {
- if (uart_circ_empty(xmit)) {
- /* disable tx interrupts */
- msm_port->imr &= ~UART_IMR_TXLEV;
- msm_write(port, msm_port->imr, UART_IMR);
+ if (!(msm_read(port, UART_SR) & UART_SR_TX_READY))
break;
- }
- msm_write(port, xmit->buf[xmit->tail],
- msm_port->is_uartdm ? UARTDM_TF : UART_TF);

if (msm_port->is_uartdm)
- reset_dm_count(port);
+ num_chars = min(tx_count - tf_pointer, sizeof(buf));
+ else
+ num_chars = 1;

- xmit->tail = (xmit->tail + 1) & (UART_XMIT_SIZE - 1);
- port->icount.tx++;
- sent_tx = 1;
+ for (i = 0; i < num_chars; i++) {
+ buf[i] = xmit->buf[xmit->tail + i];
+ port->icount.tx++;
+ }
+
+ msm_write(port, *bf, msm_port->is_uartdm ? UARTDM_TF : UART_TF);
+ xmit->tail = (xmit->tail + num_chars) & (UART_XMIT_SIZE - 1);
+ tf_pointer += num_chars;
}

+ /* disable tx interrupts if nothing more to send */
+ if (uart_circ_empty(xmit))
+ msm_stop_tx(port);
+
if (uart_circ_chars_pending(xmit) < WAKEUP_CHARS)
uart_write_wakeup(port);
}
@@ -757,7 +770,7 @@ static void msm_console_putchar(struct uart_port *port, int c)
struct msm_port *msm_port = UART_TO_MSM(port);

if (msm_port->is_uartdm)
- reset_dm_count(port);
+ reset_dm_count(port, 1);

while (!(msm_read(port, UART_SR) & UART_SR_TX_READY))
;
--
The Qualcomm Innovation Center, Inc. is a member of the Code Aurora Forum,
hosted by The Linux Foundation


\
 
 \ /
  Last update: 2013-07-24 21:21    [W:0.083 / U:0.052 seconds]
©2003-2017 Jasper Spaans. hosted at Digital OceanAdvertise on this site