serial: atmel: cleanup atmel_start+stop_tx()

Define local variables holding information about whether pdc or dma is
used in the HW. These are retested several times by calls to
atmel_use_pdc_tx() and atmel_use_dma_tx(). So to make the code more
readable, simply cache the values.

This is also a preparatory patch for the next one (where is_pdc is used
once more in atmel_stop_tx()).

Cc: Richard Genoud <[email protected]>
Cc: Nicolas Ferre <[email protected]>
Cc: Alexandre Belloni <[email protected]>
Cc: Claudiu Beznea <[email protected]>
Cc: [email protected]
Reported-by: Michael Walle <[email protected]>
Signed-off-by: Jiri Slaby (SUSE) <[email protected]>
Link: https://lore.kernel.org/r/[email protected]
Signed-off-by: Greg Kroah-Hartman <[email protected]>

Author: Jiri Slaby (SUSE)

drivers/tty/serial/atmel_serial.c

@@ -552,8 +552,9 @@ static u_int atmel_get_mctrl(struct uart_port *port)
 static void atmel_stop_tx(struct uart_port *port)
 {
 	struct atmel_uart_port *atmel_port = to_atmel_uart_port(port);
+	bool is_pdc = atmel_use_pdc_tx(port);
 
-	if (atmel_use_pdc_tx(port)) {
+	if (is_pdc) {
 		/* disable PDC transmit */
 		atmel_uart_writel(port, ATMEL_PDC_PTCR, ATMEL_PDC_TXTDIS);
 	}
@@ -572,7 +573,6 @@ static void atmel_stop_tx(struct uart_port *port)
 	if (atmel_uart_is_half_duplex(port))
 		if (!atomic_read(&atmel_port->tasklet_shutdown))
 			atmel_start_rx(port);
-
 }
 
 /*
@@ -581,20 +581,22 @@ static void atmel_stop_tx(struct uart_port *port)
 static void atmel_start_tx(struct uart_port *port)
 {
 	struct atmel_uart_port *atmel_port = to_atmel_uart_port(port);
+	bool is_pdc = atmel_use_pdc_tx(port);
+	bool is_dma = is_pdc || atmel_use_dma_tx(port);
 
-	if (atmel_use_pdc_tx(port) && (atmel_uart_readl(port, ATMEL_PDC_PTSR)
+	if (is_pdc && (atmel_uart_readl(port, ATMEL_PDC_PTSR)
 				       & ATMEL_PDC_TXTEN))
 		/* The transmitter is already running.  Yes, we
 		   really need this.*/
 		return;
 
-	if (atmel_use_pdc_tx(port) || atmel_use_dma_tx(port))
-		if (atmel_uart_is_half_duplex(port))
-			atmel_stop_rx(port);
+	if (is_dma && atmel_uart_is_half_duplex(port))
+		atmel_stop_rx(port);
 
-	if (atmel_use_pdc_tx(port))
+	if (is_pdc) {
 		/* re-enable PDC transmit */
 		atmel_uart_writel(port, ATMEL_PDC_PTCR, ATMEL_PDC_TXTEN);
+	}
 
 	/* Enable interrupts */
 	atmel_uart_writel(port, ATMEL_US_IER, atmel_port->tx_done_mask);