@@ -651,13 +651,8 @@ static void qcom_geni_serial_start_tx_fifo(struct uart_port *uport)
{
u32 irq_en;
- if (qcom_geni_serial_main_active(uport) ||
- !qcom_geni_serial_tx_empty(uport))
- return;
-
irq_en = readl(uport->membase + SE_GENI_M_IRQ_EN);
irq_en |= M_TX_FIFO_WATERMARK_EN | M_CMD_DONE_EN;
-
writel(DEF_TX_WM, uport->membase + SE_GENI_TX_WATERMARK_REG);
writel(irq_en, uport->membase + SE_GENI_M_IRQ_EN);
}
@@ -665,16 +660,28 @@ static void qcom_geni_serial_start_tx_fifo(struct uart_port *uport)
static void qcom_geni_serial_stop_tx_fifo(struct uart_port *uport)
{
u32 irq_en;
- struct qcom_geni_serial_port *port = to_dev_port(uport);
irq_en = readl(uport->membase + SE_GENI_M_IRQ_EN);
irq_en &= ~(M_CMD_DONE_EN | M_TX_FIFO_WATERMARK_EN);
writel(0, uport->membase + SE_GENI_TX_WATERMARK_REG);
writel(irq_en, uport->membase + SE_GENI_M_IRQ_EN);
- /* Possible stop tx is called multiple times. */
+}
+
+static void qcom_geni_serial_clear_tx_fifo(struct uart_port *uport)
+{
+ struct qcom_geni_serial_port *port = to_dev_port(uport);
+
if (!qcom_geni_serial_main_active(uport))
return;
+ /*
+ * Increase watermark level so that TX can be restarted and wait for
+ * sequencer to start to prevent lockups.
+ */
+ writel(port->tx_fifo_depth, uport->membase + SE_GENI_TX_WATERMARK_REG);
+ qcom_geni_serial_poll_bit(uport, SE_GENI_M_IRQ_STATUS,
+ M_TX_FIFO_WATERMARK_EN, true);
+
geni_se_cancel_m_cmd(&port->se);
if (!qcom_geni_serial_poll_bit(uport, SE_GENI_M_IRQ_STATUS,
M_CMD_CANCEL_EN, true)) {
@@ -684,6 +691,8 @@ static void qcom_geni_serial_stop_tx_fifo(struct uart_port *uport)
writel(M_CMD_ABORT_EN, uport->membase + SE_GENI_M_IRQ_CLEAR);
}
writel(M_CMD_CANCEL_EN, uport->membase + SE_GENI_M_IRQ_CLEAR);
+
+ port->tx_remaining = 0;
}
static void qcom_geni_serial_handle_rx_fifo(struct uart_port *uport, bool drop)
@@ -1069,11 +1078,10 @@ static void qcom_geni_serial_shutdown(struct uart_port *uport)
{
disable_irq(uport->irq);
- if (uart_console(uport))
- return;
-
qcom_geni_serial_stop_tx(uport);
qcom_geni_serial_stop_rx(uport);
+
+ qcom_geni_serial_clear_tx_fifo(uport);
}
static int qcom_geni_serial_port_setup(struct uart_port *uport)
The stop_tx() callback is used to implement software flow control and must not discard data as the Qualcomm GENI driver is currently doing when there is an active TX command. Cancelling an active command can also leave data in the hardware FIFO, which prevents the watermark interrupt from being enabled when TX is later restarted. This results in a soft lockup and is easily triggered by stopping TX using software flow control in a serial console but this can also happen after suspend. Fix this by only stopping any active command, and effectively clearing the hardware fifo, when shutting down the port. Make sure to temporarily raise the watermark level so that the interrupt fires when TX is restarted. Fixes: c4f528795d1a ("tty: serial: msm_geni_serial: Add serial driver support for GENI based QUP") Cc: stable@vger.kernel.org # 4.17 Signed-off-by: Johan Hovold <johan+linaro@kernel.org> --- drivers/tty/serial/qcom_geni_serial.c | 28 +++++++++++++++++---------- 1 file changed, 18 insertions(+), 10 deletions(-)