linux-kernel - [PATCH 2/2] serial: 8250_mid: Read RX buffer on RX DMA timeout for DNV

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Date:	Fri, 13 May 2016 16:15:20 +0800
From:	Chuah Kim Tatt <kim.tatt.chuah@...el.com>
To:	gregkh@...uxfoundation.org, vinod.koul@...el.com
Cc:	heikki.krogerus@...ux.intel.com, andriy.shevchenko@...ux.intel.com,
	mika.westerberg@...ux.intel.com, kim.tatt.chuah@...el.com,
	linux-kernel@...r.kernel.org, jui.nee.tan@...el.com
Subject: [PATCH 2/2] serial: 8250_mid: Read RX buffer on RX DMA timeout for DNV

From: "Chuah, Kim Tatt" <kim.tatt.chuah@...el.com>

In DNV, when RX DMA is used and number of bytes received is less than
transfer size, only RX DMA timeout interrupt is sent. When this happens,
read the RX buffer.

Signed-off-by: Chuah, Kim Tatt <kim.tatt.chuah@...el.com>
---
 drivers/tty/serial/8250/8250_mid.c | 6 ++++--
 1 file changed, 4 insertions(+), 2 deletions(-)

diff --git a/drivers/tty/serial/8250/8250_mid.c b/drivers/tty/serial/8250/8250_mid.c
index b218ff5..339de9c 100644
--- a/drivers/tty/serial/8250/8250_mid.c
+++ b/drivers/tty/serial/8250/8250_mid.c
@@ -96,6 +96,7 @@ static int tng_setup(struct mid8250 *mid, struct uart_port *p)
 static int dnv_handle_irq(struct uart_port *p)
 {
 	struct mid8250 *mid = p->private_data;
+	struct uart_8250_port *up = up_to_u8250p(p);
 	unsigned int fisr = serial_port_in(p, INTEL_MID_UART_DNV_FISR);
 	u32 status;
 	int ret = IRQ_NONE;
@@ -103,9 +104,10 @@ static int dnv_handle_irq(struct uart_port *p)
 
 	if (fisr & BIT(2)) {
 		err = hsu_dma_get_status(&mid->dma_chip, 1, &status);
-		if (err > 0)
+		if (err > 0) {
+			serial8250_rx_dma_flush(up);
 			ret |= IRQ_HANDLED;
-		else if (err == 0)
+		} else if (err == 0)
 			ret |= hsu_dma_do_irq(&mid->dma_chip, 1, status);
 	}
 	if (fisr & BIT(1)) {
-- 
1.9.1