serial: sprd: Add clearing break interrupt operation

BugLink: https://bugs.launchpad.net/bugs/1860490
commit abeb2e9414d7e3a0d8417bc3b13d7172513ea8a0 upstream.

A break interrupt will be generated if the RX line was pulled low, which
means some abnomal behaviors occurred of the UART. In this case, we still
need to clear this break interrupt status, otherwise it will cause irq
storm to crash the whole system.

Fixes: b7396a38fb28 ("tty/serial: Add Spreadtrum sc9836-uart driver support")
Signed-off-by: Yonghan Ye <yonghan.ye@unisoc.com>
Cc: stable <stable@vger.kernel.org>
Signed-off-by: Baolin Wang <baolin.wang7@gmail.com>
Link: https://lore.kernel.org/r/925e51b73099c90158e080b8f5bed9b3b38c4548.1575460601.git.baolin.wang7@gmail.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Kamal Mostafa <kamal@canonical.com>
Signed-off-by: Khalid Elmously <khalid.elmously@canonical.com>

diff --git a/drivers/tty/serial/sprd_serial.c b/drivers/tty/serial/sprd_serial.c
index f49b7d6fbc88c33d6195d12edc9ab6b354e42fd3..6f267662bd83180835e534c73a16d4f7491b6710 100644 (file)
--- a/drivers/tty/serial/sprd_serial.c
+++ b/drivers/tty/serial/sprd_serial.c
@@ -671,6 +671,9 @@ static irqreturn_t sprd_handle_irq(int irq, void *dev_id)
        if (ims & SPRD_IMSR_TIMEOUT)
                serial_out(port, SPRD_ICLR, SPRD_ICLR_TIMEOUT);
 
+       if (ims & SPRD_IMSR_BREAK_DETECT)
+               serial_out(port, SPRD_ICLR, SPRD_IMSR_BREAK_DETECT);
+
        if (ims & (SPRD_IMSR_RX_FIFO_FULL | SPRD_IMSR_BREAK_DETECT |
                   SPRD_IMSR_TIMEOUT))
                sprd_rx(port);