1 files changed, 70 insertions, 57 deletions

diff --git a/drivers/tty/serial/serial-tegra.c b/drivers/tty/serial/serial-tegra.c
index b6ace6290e23..8de8bac9c6c7 100644
--- a/drivers/tty/serial/serial-tegra.c
+++ b/drivers/tty/serial/serial-tegra.c
@@ -141,6 +141,7 @@ struct tegra_uart_port {
 	int					configured_rate;
 	bool					use_rx_pio;
 	bool					use_tx_pio;
+	bool					rx_dma_active;
 };
 
 static void tegra_uart_start_next_tx(struct tegra_uart_port *tup);
@@ -533,11 +534,12 @@ static int tegra_uart_start_tx_dma(struct tegra_uart_port *tup,
 	struct circ_buf *xmit = &tup->uport.state->xmit;
 	dma_addr_t tx_phys_addr;
 
-	dma_sync_single_for_device(tup->uport.dev, tup->tx_dma_buf_phys,
-				UART_XMIT_SIZE, DMA_TO_DEVICE);
-
 	tup->tx_bytes = count & ~(0xF);
 	tx_phys_addr = tup->tx_dma_buf_phys + xmit->tail;
+
+	dma_sync_single_for_device(tup->uport.dev, tx_phys_addr,
+				   tup->tx_bytes, DMA_TO_DEVICE);
+
 	tup->tx_dma_desc = dmaengine_prep_slave_single(tup->tx_dma_chan,
 				tx_phys_addr, tup->tx_bytes, DMA_MEM_TO_DEV,
 				DMA_PREP_INTERRUPT);
@@ -679,7 +681,7 @@ static void tegra_uart_copy_rx_to_tty(struct tegra_uart_port *tup,
 		return;
 
 	dma_sync_single_for_cpu(tup->uport.dev, tup->rx_dma_buf_phys,
-				TEGRA_UART_RX_DMA_BUFFER_SIZE, DMA_FROM_DEVICE);
+				count, DMA_FROM_DEVICE);
 	copied = tty_insert_flip_string(tty,
 			((unsigned char *)(tup->rx_dma_buf_virt)), count);
 	if (copied != count) {
@@ -687,14 +689,25 @@ static void tegra_uart_copy_rx_to_tty(struct tegra_uart_port *tup,
 		dev_err(tup->uport.dev, "RxData copy to tty layer failed\n");
 	}
 	dma_sync_single_for_device(tup->uport.dev, tup->rx_dma_buf_phys,
-				TEGRA_UART_RX_DMA_BUFFER_SIZE, DMA_TO_DEVICE);
+				   count, DMA_TO_DEVICE);
+}
+
+static void do_handle_rx_pio(struct tegra_uart_port *tup)
+{
+	struct tty_struct *tty = tty_port_tty_get(&tup->uport.state->port);
+	struct tty_port *port = &tup->uport.state->port;
+
+	tegra_uart_handle_rx_pio(tup, port);
+	if (tty) {
+		tty_flip_buffer_push(port);
+		tty_kref_put(tty);
+	}
 }
 
 static void tegra_uart_rx_buffer_push(struct tegra_uart_port *tup,
 				      unsigned int residue)
 {
 	struct tty_port *port = &tup->uport.state->port;
-	struct tty_struct *tty = tty_port_tty_get(port);
 	unsigned int count;
 
 	async_tx_ack(tup->rx_dma_desc);
@@ -703,11 +716,7 @@ static void tegra_uart_rx_buffer_push(struct tegra_uart_port *tup,
 	/* If we are here, DMA is stopped */
 	tegra_uart_copy_rx_to_tty(tup, port, count);
 
-	tegra_uart_handle_rx_pio(tup, port);
-	if (tty) {
-		tty_flip_buffer_push(port);
-		tty_kref_put(tty);
-	}
+	do_handle_rx_pio(tup);
 }
 
 static void tegra_uart_rx_dma_complete(void *args)
@@ -731,6 +740,7 @@ static void tegra_uart_rx_dma_complete(void *args)
 	if (tup->rts_active)
 		set_rts(tup, false);
 
+	tup->rx_dma_active = false;
 	tegra_uart_rx_buffer_push(tup, 0);
 	tegra_uart_start_rx_dma(tup);
 
@@ -742,18 +752,29 @@ done:
 	spin_unlock_irqrestore(&u->lock, flags);
 }
 
-static void tegra_uart_handle_rx_dma(struct tegra_uart_port *tup)
+static void tegra_uart_terminate_rx_dma(struct tegra_uart_port *tup)
 {
 	struct dma_tx_state state;
 
-	/* Deactivate flow control to stop sender */
-	if (tup->rts_active)
-		set_rts(tup, false);
+	if (!tup->rx_dma_active) {
+		do_handle_rx_pio(tup);
+		return;
+	}
 
 	dmaengine_terminate_all(tup->rx_dma_chan);
 	dmaengine_tx_status(tup->rx_dma_chan, tup->rx_cookie, &state);
+
 	tegra_uart_rx_buffer_push(tup, state.residue);
-	tegra_uart_start_rx_dma(tup);
+	tup->rx_dma_active = false;
+}
+
+static void tegra_uart_handle_rx_dma(struct tegra_uart_port *tup)
+{
+	/* Deactivate flow control to stop sender */
+	if (tup->rts_active)
+		set_rts(tup, false);
+
+	tegra_uart_terminate_rx_dma(tup);
 
 	if (tup->rts_active)
 		set_rts(tup, true);
@@ -763,6 +784,9 @@ static int tegra_uart_start_rx_dma(struct tegra_uart_port *tup)
 {
 	unsigned int count = TEGRA_UART_RX_DMA_BUFFER_SIZE;
 
+	if (tup->rx_dma_active)
+		return 0;
+
 	tup->rx_dma_desc = dmaengine_prep_slave_single(tup->rx_dma_chan,
 				tup->rx_dma_buf_phys, count, DMA_DEV_TO_MEM,
 				DMA_PREP_INTERRUPT);
@@ -771,10 +795,9 @@ static int tegra_uart_start_rx_dma(struct tegra_uart_port *tup)
 		return -EIO;
 	}
 
+	tup->rx_dma_active = true;
 	tup->rx_dma_desc->callback = tegra_uart_rx_dma_complete;
 	tup->rx_dma_desc->callback_param = tup;
-	dma_sync_single_for_device(tup->uport.dev, tup->rx_dma_buf_phys,
-				count, DMA_TO_DEVICE);
 	tup->rx_bytes_requested = count;
 	tup->rx_cookie = dmaengine_submit(tup->rx_dma_desc);
 	dma_async_issue_pending(tup->rx_dma_chan);
@@ -802,24 +825,13 @@ static void tegra_uart_handle_modem_signal_change(struct uart_port *u)
 		uart_handle_cts_change(&tup->uport, msr & UART_MSR_CTS);
 }
 
-static void do_handle_rx_pio(struct tegra_uart_port *tup)
-{
-	struct tty_struct *tty = tty_port_tty_get(&tup->uport.state->port);
-	struct tty_port *port = &tup->uport.state->port;
-
-	tegra_uart_handle_rx_pio(tup, port);
-	if (tty) {
-		tty_flip_buffer_push(port);
-		tty_kref_put(tty);
-	}
-}
-
 static irqreturn_t tegra_uart_isr(int irq, void *data)
 {
 	struct tegra_uart_port *tup = data;
 	struct uart_port *u = &tup->uport;
 	unsigned long iir;
 	unsigned long ier;
+	bool is_rx_start = false;
 	bool is_rx_int = false;
 	unsigned long flags;
 
@@ -832,10 +844,12 @@ static irqreturn_t tegra_uart_isr(int irq, void *data)
 				if (tup->rx_in_progress) {
 					ier = tup->ier_shadow;
 					ier |= (UART_IER_RLSI | UART_IER_RTOIE |
-						TEGRA_UART_IER_EORD);
+						TEGRA_UART_IER_EORD | UART_IER_RDI);
 					tup->ier_shadow = ier;
 					tegra_uart_write(tup, ier, UART_IER);
 				}
+			} else if (is_rx_start) {
+				tegra_uart_start_rx_dma(tup);
 			}
 			spin_unlock_irqrestore(&u->lock, flags);
 			return IRQ_HANDLED;
@@ -854,17 +868,23 @@ static irqreturn_t tegra_uart_isr(int irq, void *data)
 
 		case 4: /* End of data */
 		case 6: /* Rx timeout */
-		case 2: /* Receive */
-			if (!tup->use_rx_pio && !is_rx_int) {
-				is_rx_int = true;
+			if (!tup->use_rx_pio) {
+				is_rx_int = tup->rx_in_progress;
 				/* Disable Rx interrupts */
 				ier = tup->ier_shadow;
-				ier |= UART_IER_RDI;
-				tegra_uart_write(tup, ier, UART_IER);
 				ier &= ~(UART_IER_RDI | UART_IER_RLSI |
 					UART_IER_RTOIE | TEGRA_UART_IER_EORD);
 				tup->ier_shadow = ier;
 				tegra_uart_write(tup, ier, UART_IER);
+				break;
+			}
+			/* Fall through */
+		case 2: /* Receive */
+			if (!tup->use_rx_pio) {
+				is_rx_start = tup->rx_in_progress;
+				tup->ier_shadow  &= ~UART_IER_RDI;
+				tegra_uart_write(tup, tup->ier_shadow,
+						 UART_IER);
 			} else {
 				do_handle_rx_pio(tup);
 			}
@@ -886,7 +906,6 @@ static void tegra_uart_stop_rx(struct uart_port *u)
 {
 	struct tegra_uart_port *tup = to_tegra_uport(u);
 	struct tty_port *port = &tup->uport.state->port;
-	struct dma_tx_state state;
 	unsigned long ier;
 
 	if (tup->rts_active)
@@ -903,13 +922,11 @@ static void tegra_uart_stop_rx(struct uart_port *u)
 	tup->ier_shadow = ier;
 	tegra_uart_write(tup, ier, UART_IER);
 	tup->rx_in_progress = 0;
-	if (tup->rx_dma_chan && !tup->use_rx_pio) {
-		dmaengine_terminate_all(tup->rx_dma_chan);
-		dmaengine_tx_status(tup->rx_dma_chan, tup->rx_cookie, &state);
-		tegra_uart_rx_buffer_push(tup, state.residue);
-	} else {
+
+	if (!tup->use_rx_pio)
+		tegra_uart_terminate_rx_dma(tup);
+	else
 		tegra_uart_handle_rx_pio(tup, port);
-	}
 }
 
 static void tegra_uart_hw_deinit(struct tegra_uart_port *tup)
@@ -1052,12 +1069,6 @@ static int tegra_uart_hw_init(struct tegra_uart_port *tup)
 		tup->lcr_shadow = TEGRA_UART_DEFAULT_LSR;
 		tup->fcr_shadow |= UART_FCR_DMA_SELECT;
 		tegra_uart_write(tup, tup->fcr_shadow, UART_FCR);
-
-		ret = tegra_uart_start_rx_dma(tup);
-		if (ret < 0) {
-			dev_err(tup->uport.dev, "Not able to start Rx DMA\n");
-			return ret;
-		}
 	} else {
 		tegra_uart_write(tup, tup->fcr_shadow, UART_FCR);
 	}
@@ -1067,10 +1078,6 @@ static int tegra_uart_hw_init(struct tegra_uart_port *tup)
 	 * Enable IE_RXS for the receive status interrupts like line errros.
 	 * Enable IE_RX_TIMEOUT to get the bytes which cannot be DMA'd.
 	 *
-	 * If using DMA mode, enable EORD instead of receive interrupt which
-	 * will interrupt after the UART is done with the receive instead of
-	 * the interrupt when the FIFO "threshold" is reached.
-	 *
 	 * EORD is different interrupt than RX_TIMEOUT - RX_TIMEOUT occurs when
 	 * the DATA is sitting in the FIFO and couldn't be transferred to the
 	 * DMA as the DMA size alignment (4 bytes) is not met. EORD will be
@@ -1081,11 +1088,14 @@ static int tegra_uart_hw_init(struct tegra_uart_port *tup)
 	 * both the EORD as well as RX_TIMEOUT - SW sees RX_TIMEOUT first
 	 * then the EORD.
 	 */
+	tup->ier_shadow = UART_IER_RLSI | UART_IER_RTOIE | UART_IER_RDI;
+
+	/*
+	 * If using DMA mode, enable EORD interrupt to notify about RX
+	 * completion.
+	 */
 	if (!tup->use_rx_pio)
-		tup->ier_shadow = UART_IER_RLSI | UART_IER_RTOIE |
-			TEGRA_UART_IER_EORD;
-	else
-		tup->ier_shadow = UART_IER_RLSI | UART_IER_RTOIE | UART_IER_RDI;
+		tup->ier_shadow |= TEGRA_UART_IER_EORD;
 
 	tegra_uart_write(tup, tup->ier_shadow, UART_IER);
 	return 0;
@@ -1140,6 +1150,9 @@ static int tegra_uart_dma_channel_allocate(struct tegra_uart_port *tup,
 			dma_release_channel(dma_chan);
 			return -ENOMEM;
 		}
+		dma_sync_single_for_device(tup->uport.dev, dma_phys,
+					   TEGRA_UART_RX_DMA_BUFFER_SIZE,
+					   DMA_TO_DEVICE);
 		dma_sconfig.src_addr = tup->uport.mapbase;
 		dma_sconfig.src_addr_width = DMA_SLAVE_BUSWIDTH_1_BYTE;
 		dma_sconfig.src_maxburst = tup->cdata->max_dma_burst_bytes;