[PATCH] tty: serial: qcom_geni_serial: Fix UART hang

[Ryan Case]

If a serial console write occured while a UART transmit command was
waiting for a done signal then no further data would be sent until
something new kicked the system into gear. If there is already data
waiting in the circular buffer we must re-enable the tx watermark so we
receive the expected interrupts.

Signed-off-by: Ryan Case <ryandc...@chromium.org>
---

 drivers/tty/serial/qcom_geni_serial.c | 8 ++++++++
 1 file changed, 8 insertions(+)

diff --git a/drivers/tty/serial/qcom_geni_serial.c 
b/drivers/tty/serial/qcom_geni_serial.c
index 0c93beb69e73..a694a47747c7 100644
--- a/drivers/tty/serial/qcom_geni_serial.c
+++ b/drivers/tty/serial/qcom_geni_serial.c
@@ -442,6 +442,7 @@ static void qcom_geni_serial_console_write(struct console 
*co, const char *s,
        bool locked = true;
        unsigned long flags;
        u32 geni_status;
+       u32 irq_en;
 
        WARN_ON(co->index < 0 || co->index >= GENI_UART_CONS_PORTS);
 
@@ -476,6 +477,13 @@ static void qcom_geni_serial_console_write(struct console 
*co, const char *s,
                 * has been sent, in which case we need to look for done first.
                 */
                qcom_geni_serial_poll_tx_done(uport);
+
+               if (uart_circ_chars_pending(&uport->state->xmit)) {
+                       irq_en = readl_relaxed(uport->membase +
+                                       SE_GENI_M_IRQ_EN);
+                       writel_relaxed(irq_en | M_TX_FIFO_WATERMARK_EN,
+                                       uport->membase + SE_GENI_M_IRQ_EN);
+               }
        }
 
        __qcom_geni_serial_console_write(uport, s, count);
-- 
2.20.1.415.g653613c723-goog