1 files changed, 48 insertions, 40 deletions

diff --git a/drivers/tty/serial/imx.c b/drivers/tty/serial/imx.c
index 57d6e6ba556e..87c58f9f6390 100644
--- a/drivers/tty/serial/imx.c
+++ b/drivers/tty/serial/imx.c
@@ -402,12 +402,6 @@ static void imx_uart_rts_inactive(struct imx_port *sport, u32 *ucr2)
 	mctrl_gpio_set(sport->gpios, sport->port.mctrl);
 }
 
-/* called with port.lock taken and irqs caller dependent */
-static void imx_uart_rts_auto(struct imx_port *sport, u32 *ucr2)
-{
-	*ucr2 |= UCR2_CTSC;
-}
-
 /* called with port.lock taken and irqs off */
 static void imx_uart_start_rx(struct uart_port *port)
 {
@@ -445,7 +439,7 @@ static void imx_uart_stop_tx(struct uart_port *port)
 		return;
 
 	ucr1 = imx_uart_readl(sport, UCR1);
-	imx_uart_writel(sport, ucr1 & ~UCR1_TXMPTYEN, UCR1);
+	imx_uart_writel(sport, ucr1 & ~UCR1_TRDYEN, UCR1);
 
 	/* in rs485 mode disable transmitter if shifter is empty */
 	if (port->rs485.flags & SER_RS485_ENABLED &&
@@ -523,7 +517,7 @@ static inline void imx_uart_transmit_buffer(struct imx_port *sport)
 		 * and the TX IRQ is disabled.
 		 **/
 		ucr1 = imx_uart_readl(sport, UCR1);
-		ucr1 &= ~UCR1_TXMPTYEN;
+		ucr1 &= ~UCR1_TRDYEN;
 		if (sport->dma_is_txing) {
 			ucr1 |= UCR1_TXDMAEN;
 			imx_uart_writel(sport, ucr1, UCR1);
@@ -685,7 +679,7 @@ static void imx_uart_start_tx(struct uart_port *port)
 
 	if (!sport->dma_is_enabled) {
 		ucr1 = imx_uart_readl(sport, UCR1);
-		imx_uart_writel(sport, ucr1 | UCR1_TXMPTYEN, UCR1);
+		imx_uart_writel(sport, ucr1 | UCR1_TRDYEN, UCR1);
 	}
 
 	if (sport->dma_is_enabled) {
@@ -694,7 +688,7 @@ static void imx_uart_start_tx(struct uart_port *port)
 			 * disable TX DMA to let TX interrupt to send X-char */
 			ucr1 = imx_uart_readl(sport, UCR1);
 			ucr1 &= ~UCR1_TXDMAEN;
-			ucr1 |= UCR1_TXMPTYEN;
+			ucr1 |= UCR1_TRDYEN;
 			imx_uart_writel(sport, ucr1, UCR1);
 			return;
 		}
@@ -880,7 +874,7 @@ static irqreturn_t imx_uart_int(int irq, void *dev_id)
 		usr1 &= ~USR1_RRDY;
 	if ((ucr2 & UCR2_ATEN) == 0)
 		usr1 &= ~USR1_AGTIM;
-	if ((ucr1 & UCR1_TXMPTYEN) == 0)
+	if ((ucr1 & UCR1_TRDYEN) == 0)
 		usr1 &= ~USR1_TRDY;
 	if ((ucr4 & UCR4_TCEN) == 0)
 		usr2 &= ~USR2_TXDC;
@@ -969,10 +963,22 @@ static void imx_uart_set_mctrl(struct uart_port *port, unsigned int mctrl)
 	if (!(port->rs485.flags & SER_RS485_ENABLED)) {
 		u32 ucr2;
 
+		/*
+		 * Turn off autoRTS if RTS is lowered and restore autoRTS
+		 * setting if RTS is raised.
+		 */
 		ucr2 = imx_uart_readl(sport, UCR2);
 		ucr2 &= ~(UCR2_CTS | UCR2_CTSC);
-		if (mctrl & TIOCM_RTS)
-			ucr2 |= UCR2_CTS | UCR2_CTSC;
+		if (mctrl & TIOCM_RTS) {
+			ucr2 |= UCR2_CTS;
+			/*
+			 * UCR2_IRTS is unset if and only if the port is
+			 * configured for CRTSCTS, so we use inverted UCR2_IRTS
+			 * to get the state to restore to.
+			 */
+			if (!(ucr2 & UCR2_IRTS))
+				ucr2 |= UCR2_CTSC;
+		}
 		imx_uart_writel(sport, ucr2, UCR2);
 	}
 
@@ -1468,7 +1474,7 @@ static void imx_uart_shutdown(struct uart_port *port)
 
 	spin_lock_irqsave(&sport->port.lock, flags);
 	ucr1 = imx_uart_readl(sport, UCR1);
-	ucr1 &= ~(UCR1_TXMPTYEN | UCR1_RRDYEN | UCR1_RTSDEN | UCR1_UARTEN | UCR1_RXDMAEN | UCR1_ATDMAEN);
+	ucr1 &= ~(UCR1_TRDYEN | UCR1_RRDYEN | UCR1_RTSDEN | UCR1_UARTEN | UCR1_RXDMAEN | UCR1_ATDMAEN);
 
 	imx_uart_writel(sport, ucr1, UCR1);
 	spin_unlock_irqrestore(&sport->port.lock, flags);
@@ -1535,11 +1541,11 @@ imx_uart_set_termios(struct uart_port *port, struct ktermios *termios,
 {
 	struct imx_port *sport = (struct imx_port *)port;
 	unsigned long flags;
-	u32 ucr2, old_ucr1, old_ucr2, ufcr;
+	u32 ucr2, old_ucr2, ufcr;
 	unsigned int baud, quot;
 	unsigned int old_csize = old ? old->c_cflag & CSIZE : CS8;
 	unsigned long div;
-	unsigned long num, denom;
+	unsigned long num, denom, old_ubir, old_ubmr;
 	uint64_t tdiv64;
 
 	/*
@@ -1587,8 +1593,14 @@ imx_uart_set_termios(struct uart_port *port, struct ktermios *termios,
 		else
 			imx_uart_rts_inactive(sport, &ucr2);
 
-	} else if (termios->c_cflag & CRTSCTS)
-		imx_uart_rts_auto(sport, &ucr2);
+	} else if (termios->c_cflag & CRTSCTS) {
+		/*
+		 * Only let receiver control RTS output if we were not requested
+		 * to have RTS inactive (which then should take precedence).
+		 */
+		if (ucr2 & UCR2_CTS)
+			ucr2 |= UCR2_CTSC;
+	}
 
 	if (termios->c_cflag & CRTSCTS)
 		ucr2 &= ~UCR2_IRTS;
@@ -1631,21 +1643,6 @@ imx_uart_set_termios(struct uart_port *port, struct ktermios *termios,
 	 */
 	uart_update_timeout(port, termios->c_cflag, baud);
 
-	/*
-	 * disable interrupts and drain transmitter
-	 */
-	old_ucr1 = imx_uart_readl(sport, UCR1);
-	imx_uart_writel(sport,
-			old_ucr1 & ~(UCR1_TXMPTYEN | UCR1_RRDYEN | UCR1_RTSDEN),
-			UCR1);
-	imx_uart_writel(sport, old_ucr2 & ~UCR2_ATEN, UCR2);
-
-	while (!(imx_uart_readl(sport, USR2) & USR2_TXDC))
-		barrier();
-
-	/* then, disable everything */
-	imx_uart_writel(sport, old_ucr2 & ~(UCR2_TXEN | UCR2_RXEN | UCR2_ATEN), UCR2);
-
 	/* custom-baudrate handling */
 	div = sport->port.uartclk / (baud * 16);
 	if (baud == 38400 && quot != div)
@@ -1673,15 +1670,26 @@ imx_uart_set_termios(struct uart_port *port, struct ktermios *termios,
 	ufcr = (ufcr & (~UFCR_RFDIV)) | UFCR_RFDIV_REG(div);
 	imx_uart_writel(sport, ufcr, UFCR);
 
-	imx_uart_writel(sport, num, UBIR);
-	imx_uart_writel(sport, denom, UBMR);
+	/*
+	 *  Two registers below should always be written both and in this
+	 *  particular order. One consequence is that we need to check if any of
+	 *  them changes and then update both. We do need the check for change
+	 *  as even writing the same values seem to "restart"
+	 *  transmission/receiving logic in the hardware, that leads to data
+	 *  breakage even when rate doesn't in fact change. E.g., user switches
+	 *  RTS/CTS handshake and suddenly gets broken bytes.
+	 */
+	old_ubir = imx_uart_readl(sport, UBIR);
+	old_ubmr = imx_uart_readl(sport, UBMR);
+	if (old_ubir != num || old_ubmr != denom) {
+		imx_uart_writel(sport, num, UBIR);
+		imx_uart_writel(sport, denom, UBMR);
+	}
 
 	if (!imx_uart_is_imx1(sport))
 		imx_uart_writel(sport, sport->port.uartclk / div / 1000,
 				IMX21_ONEMS);
 
-	imx_uart_writel(sport, old_ucr1, UCR1);
-
 	imx_uart_writel(sport, ucr2, UCR2);
 
 	if (UART_ENABLE_MS(&sport->port, termios->c_cflag))
@@ -1770,7 +1778,7 @@ static int imx_uart_poll_init(struct uart_port *port)
 		ucr1 |= IMX1_UCR1_UARTCLKEN;
 
 	ucr1 |= UCR1_UARTEN;
-	ucr1 &= ~(UCR1_TXMPTYEN | UCR1_RTSDEN | UCR1_RRDYEN);
+	ucr1 &= ~(UCR1_TRDYEN | UCR1_RTSDEN | UCR1_RRDYEN);
 
 	ucr2 |= UCR2_RXEN;
 	ucr2 &= ~UCR2_ATEN;
@@ -1930,7 +1938,7 @@ imx_uart_console_write(struct console *co, const char *s, unsigned int count)
 	if (imx_uart_is_imx1(sport))
 		ucr1 |= IMX1_UCR1_UARTCLKEN;
 	ucr1 |= UCR1_UARTEN;
-	ucr1 &= ~(UCR1_TXMPTYEN | UCR1_RRDYEN | UCR1_RTSDEN);
+	ucr1 &= ~(UCR1_TRDYEN | UCR1_RRDYEN | UCR1_RTSDEN);
 
 	imx_uart_writel(sport, ucr1, UCR1);
 
@@ -2286,7 +2294,7 @@ static int imx_uart_probe(struct platform_device *pdev)
 	/* Disable interrupts before requesting them */
 	ucr1 = imx_uart_readl(sport, UCR1);
 	ucr1 &= ~(UCR1_ADEN | UCR1_TRDYEN | UCR1_IDEN | UCR1_RRDYEN |
-		 UCR1_TXMPTYEN | UCR1_RTSDEN);
+		 UCR1_TRDYEN | UCR1_RTSDEN);
 	imx_uart_writel(sport, ucr1, UCR1);
 
 	if (!imx_uart_is_imx1(sport) && sport->dte_mode) {