serial: tegra_hsuart: Fix sleeping while atomic

Move the flush_work outside of stop_tx, do it during suspend and
shutdown instead.  Move the tty portion of the tx work into
the dma complete callback, and only handle polling on the fifo and
then requeuing the dma in the work function.

Change-Id: I56db6504d35e5e7019379dc8a4323b4a27c72e59
Signed-off-by: Colin Cross <ccross@android.com>

1 files changed, 26 insertions, 15 deletions

diff --git a/drivers/serial/tegra_hsuart.c b/drivers/serial/tegra_hsuart.c
index 785cfb229779..292863ccaaa0 100644
--- a/drivers/serial/tegra_hsuart.c
+++ b/drivers/serial/tegra_hsuart.c
@@ -416,13 +416,9 @@ static void tegra_tx_dma_complete_work(struct work_struct *work)
 	struct tegra_uart_port *t =
 			container_of(work, struct tegra_uart_port, tx_work);
 	struct tegra_dma_req *req = &t->tx_dma_req;
-	struct circ_buf *xmit = &t->uport.state->xmit;
-	int count = req->bytes_transferred;
 	unsigned long flags;
 	int timeout = 20;
 
-	dev_vdbg(t->uport.dev, "%s: %d\n", __func__, count);
-
 	while ((uart_readb(t, UART_LSR) & TX_EMPTY_STATUS) != TX_EMPTY_STATUS) {
 		timeout--;
 		if (timeout == 0) {
@@ -434,11 +430,8 @@ static void tegra_tx_dma_complete_work(struct work_struct *work)
 	}
 
 	spin_lock_irqsave(&t->uport.lock, flags);
-	xmit->tail = (xmit->tail + count) & (UART_XMIT_SIZE - 1);
-	t->tx_in_progress = 0;
 
-	if (uart_circ_chars_pending(xmit) < WAKEUP_CHARS)
-		uart_write_wakeup(&t->uport);
+	t->tx_in_progress = 0;
 
 	if (req->status != -TEGRA_DMA_REQ_ERROR_ABORTED)
 		tegra_start_next_tx(t);
@@ -449,7 +442,21 @@ static void tegra_tx_dma_complete_work(struct work_struct *work)
 static void tegra_tx_dma_complete_callback(struct tegra_dma_req *req)
 {
 	struct tegra_uart_port *t = req->dev;
+	struct circ_buf *xmit = &t->uport.state->xmit;
+	int count = req->bytes_transferred;
+	unsigned long flags;
+
+	dev_vdbg(t->uport.dev, "%s: %d\n", __func__, count);
+
+	spin_lock_irqsave(&t->uport.lock, flags);
+	xmit->tail = (xmit->tail + count) & (UART_XMIT_SIZE - 1);
+
+	if (uart_circ_chars_pending(xmit) < WAKEUP_CHARS)
+		uart_write_wakeup(&t->uport);
+
 	schedule_work(&t->tx_work);
+
+	spin_unlock_irqrestore(&t->uport.lock, flags);
 }
 
 static irqreturn_t tegra_uart_isr(int irq, void *data)
@@ -552,6 +559,9 @@ static void tegra_stop_rx(struct uart_port *u)
 static void tegra_uart_hw_deinit(struct tegra_uart_port *t)
 {
 	unsigned char fcr;
+	unsigned long flags;
+
+	flush_work(&t->tx_work);
 
 	/* Disable interrupts */
 	uart_writeb(t, 0, UART_IER);
@@ -559,6 +569,8 @@ static void tegra_uart_hw_deinit(struct tegra_uart_port *t)
 	while ((uart_readb(t, UART_LSR) & UART_LSR_TEMT) != UART_LSR_TEMT);
 		udelay(200);
 
+	spin_lock_irqsave(&t->uport.lock, flags);
+
 	/* Reset the Rx and Tx FIFOs */
 	fcr = t->fcr_shadow;
 	fcr |= UART_FCR_CLEAR_XMIT | UART_FCR_CLEAR_RCVR;
@@ -568,6 +580,8 @@ static void tegra_uart_hw_deinit(struct tegra_uart_port *t)
 
 	clk_disable(t->clk);
 	t->baud = 0;
+
+	spin_unlock_irqrestore(&t->uport.lock, flags);
 }
 
 static void tegra_uart_free_rx_dma(struct tegra_uart_port *t)
@@ -805,14 +819,11 @@ fail:
 static void tegra_shutdown(struct uart_port *u)
 {
 	struct tegra_uart_port *t;
-	unsigned long flags;
 
-	spin_lock_irqsave(&u->lock, flags);
 	t = container_of(u, struct tegra_uart_port, uport);
 	dev_vdbg(u->dev, "+tegra_shutdown\n");
 
 	tegra_uart_hw_deinit(t);
-	spin_unlock_irqrestore(&u->lock, flags);
 
 	t->rx_in_progress = 0;
 	t->tx_in_progress = 0;
@@ -947,11 +958,9 @@ static void tegra_stop_tx(struct uart_port *u)
 
 	t = container_of(u, struct tegra_uart_port, uport);
 
-	if (t->use_tx_dma) {
+	if (t->use_tx_dma)
 		tegra_dma_dequeue_req(t->tx_dma, &t->tx_dma_req);
-		flush_work(&t->tx_work);
-	}
-	t->tx_in_progress  = 0;
+
 	return;
 }
 
@@ -1170,6 +1179,8 @@ static int tegra_uart_suspend(struct platform_device *pdev, pm_message_t state)
 
 	u = &t->uport;
 	uart_suspend_port(&tegra_uart_driver, u);
+
+	flush_work(&t->tx_work);
 	return 0;
 }