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path: root/drivers/tty/serial/amba-pl011.c
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Diffstat (limited to 'drivers/tty/serial/amba-pl011.c')
-rw-r--r--drivers/tty/serial/amba-pl011.c16
1 files changed, 16 insertions, 0 deletions
diff --git a/drivers/tty/serial/amba-pl011.c b/drivers/tty/serial/amba-pl011.c
index 4b40a5b449ee..ebd33c0232e6 100644
--- a/drivers/tty/serial/amba-pl011.c
+++ b/drivers/tty/serial/amba-pl011.c
@@ -1727,10 +1727,26 @@ static int pl011_allocate_irq(struct uart_amba_port *uap)
*/
static void pl011_enable_interrupts(struct uart_amba_port *uap)
{
+ unsigned int i;
+
spin_lock_irq(&uap->port.lock);
/* Clear out any spuriously appearing RX interrupts */
pl011_write(UART011_RTIS | UART011_RXIS, uap, REG_ICR);
+
+ /*
+ * RXIS is asserted only when the RX FIFO transitions from below
+ * to above the trigger threshold. If the RX FIFO is already
+ * full to the threshold this can't happen and RXIS will now be
+ * stuck off. Drain the RX FIFO explicitly to fix this:
+ */
+ for (i = 0; i < uap->fifosize * 2; ++i) {
+ if (pl011_read(uap, REG_FR) & UART01x_FR_RXFE)
+ break;
+
+ pl011_read(uap, REG_DR);
+ }
+
uap->im = UART011_RTIM;
if (!pl011_dma_rx_running(uap))
uap->im |= UART011_RXIM;