0038-serial-8250_dma-stop-ongoing-RX-DMA-on-exception.patch

From 0000000000000000000000000000000000000000 Mon Sep 17 00:00:00 2001
From: Jeremy Compostella <jeremy.compostella@intel.com>
Date: Thu, 8 Nov 2018 11:11:00 +0530
Subject: [PATCH] serial: 8250_dma: stop ongoing RX DMA on exception

If we get an exeption interrupt. i.e. UART_IIR_RLSI, stop
any ongoing RX DMA transfer otherwise it might generate
more spurious interrupts and make port unavailable anymore.

As has been seen on Intel Broxton system:
...
[  168.526281] serial8250: too much work for irq5
[  168.535908] serial8250: too much work for irq5
[  173.449464] serial8250_interrupt: 4439 callbacks suppressed
[  173.455694] serial8250: too much work for irq5
...

Signed-off-by: Jeremy Compostella <jeremy.compostella@intel.com>
---
 drivers/tty/serial/8250/8250_port.c | 3 +--
 1 file changed, 1 insertion(+), 2 deletions(-)

diff --git a/drivers/tty/serial/8250/8250_port.c b/drivers/tty/serial/8250/8250_port.c
index 60ca19eca1f6..6d2e07fbbba6 100644
--- a/drivers/tty/serial/8250/8250_port.c
+++ b/drivers/tty/serial/8250/8250_port.c
@@ -1845,9 +1845,8 @@ static bool handle_rx_dma(struct uart_8250_port *up, unsigned int iir)
 {
 	switch (iir & 0x3f) {
 	case UART_IIR_RX_TIMEOUT:
-		serial8250_rx_dma_flush(up);
-		/* fall-through */
 	case UART_IIR_RLSI:
+		serial8250_rx_dma_flush(up);
 		return true;
 	}
 	return up->dma->rx_dma(up);
-- 
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