@@ -159,6 +159,8 @@ struct uart_omap_port {
u32 calc_latency;
struct work_struct qos_work;
bool is_suspending;
+
+ unsigned int rs485_tx_filter_count;
};
#define to_uart_omap_port(p) ((container_of((p), struct uart_omap_port, port)))
@@ -328,19 +330,6 @@ static void serial_omap_stop_tx(struct uart_port *port)
serial_out(up, UART_IER, up->ier);
}
- if ((port->rs485.flags & SER_RS485_ENABLED) &&
- !(port->rs485.flags & SER_RS485_RX_DURING_TX)) {
- /*
- * Empty the RX FIFO, we are not interested in anything
- * received during the half-duplex transmission.
- */
- serial_out(up, UART_FCR, up->fcr | UART_FCR_CLEAR_RCVR);
- /* Re-enable RX interrupts */
- up->ier |= UART_IER_RLSI | UART_IER_RDI;
- up->port.read_status_mask |= UART_LSR_DR;
- serial_out(up, UART_IER, up->ier);
- }
-
pm_runtime_mark_last_busy(up->dev);
pm_runtime_put_autosuspend(up->dev);
}
@@ -366,6 +355,10 @@ static void transmit_chars(struct uart_omap_port *up, unsigned int lsr)
serial_out(up, UART_TX, up->port.x_char);
up->port.icount.tx++;
up->port.x_char = 0;
+ if ((up->port.rs485.flags & SER_RS485_ENABLED) &&
+ !(up->port.rs485.flags & SER_RS485_RX_DURING_TX))
+ up->rs485_tx_filter_count++;
+
return;
}
if (uart_circ_empty(xmit) || uart_tx_stopped(&up->port)) {
@@ -377,6 +370,10 @@ static void transmit_chars(struct uart_omap_port *up, unsigned int lsr)
serial_out(up, UART_TX, xmit->buf[xmit->tail]);
xmit->tail = (xmit->tail + 1) & (UART_XMIT_SIZE - 1);
up->port.icount.tx++;
+ if ((up->port.rs485.flags & SER_RS485_ENABLED) &&
+ !(up->port.rs485.flags & SER_RS485_RX_DURING_TX))
+ up->rs485_tx_filter_count++;
+
if (uart_circ_empty(xmit))
break;
} while (--count > 0);
@@ -420,7 +417,7 @@ static void serial_omap_start_tx(struct uart_port *port)
if ((port->rs485.flags & SER_RS485_ENABLED) &&
!(port->rs485.flags & SER_RS485_RX_DURING_TX))
- serial_omap_stop_rx(port);
+ up->rs485_tx_filter_count = 0;
serial_omap_enable_ier_thri(up);
pm_runtime_mark_last_busy(up->dev);
@@ -491,8 +488,13 @@ static void serial_omap_rlsi(struct uart_omap_port *up, unsigned int lsr)
* Read one data character out to avoid stalling the receiver according
* to the table 23-246 of the omap4 TRM.
*/
- if (likely(lsr & UART_LSR_DR))
+ if (likely(lsr & UART_LSR_DR)) {
serial_in(up, UART_RX);
+ if ((up->port.rs485.flags & SER_RS485_ENABLED) &&
+ !(up->port.rs485.flags & SER_RS485_RX_DURING_TX) &&
+ up->rs485_tx_filter_count)
+ up->rs485_tx_filter_count--;
+ }
up->port.icount.rx++;
flag = TTY_NORMAL;
@@ -543,6 +545,13 @@ static void serial_omap_rdi(struct uart_omap_port *up, unsigned int lsr)
return;
ch = serial_in(up, UART_RX);
+ if ((up->port.rs485.flags & SER_RS485_ENABLED) &&
+ !(up->port.rs485.flags & SER_RS485_RX_DURING_TX) &&
+ up->rs485_tx_filter_count) {
+ up->rs485_tx_filter_count--;
+ return;
+ }
+
flag = TTY_NORMAL;
up->port.icount.rx++;
Data received during half-duplex transmission must be filtered. If the target device responds quickly, emptying the FIFO at the end of the transmission can erase not only the echo characters but also part of the response message. By keeping the receive interrupt enabled even during transmission, it allows you to filter each echo character and only in a number equal to those transmitted. The issue was generated by a target device that started responding 240us later having received a request in communication at 115200bps. Sometimes, some messages received by the target were missing some of the first bytes. Fixes: 3a13884abea0 ("tty/serial: omap: empty the RX FIFO at the end of half-duplex TX") Signed-off-by: Dario Binacchi <dariobin@libero.it> --- Changes in v4: - Change the type of the rs485_tx_filter_count variable from atomic_t to unsigned int and related read / write accesses. Changes in v3: - Add 'Fixes' tag Changes in v2: - Fix compiling error drivers/tty/serial/omap-serial.c | 39 ++++++++++++++++++++------------ 1 file changed, 24 insertions(+), 15 deletions(-)