[PATCH RFC 4/4] serial: imx-serial - update RX error counters when DMA is used

From: Nandor Han
Date: Thu Jun 09 2016 - 09:03:41 EST


Update error couters when DMA is used for receiving data. Do
this by using DMA transaction error event instead error interrupts
to reduce interrupt load.

Signed-off-by: Nandor Han <nandor.han@xxxxxx>
---
drivers/tty/serial/imx.c | 32 ++++++++++++++++++++++++++++++++
1 file changed, 32 insertions(+)

diff --git a/drivers/tty/serial/imx.c b/drivers/tty/serial/imx.c
index 1912136..08ccfe1 100644
--- a/drivers/tty/serial/imx.c
+++ b/drivers/tty/serial/imx.c
@@ -704,6 +704,7 @@ out:
return IRQ_HANDLED;
}

+static void clear_rx_errors(struct imx_port *sport);
static int start_rx_dma(struct imx_port *sport);
/*
* If the RXFIFO is filled with some data, and then we
@@ -729,6 +730,11 @@ static void imx_dma_rxint(struct imx_port *sport)
temp &= ~(UCR2_ATEN);
writel(temp, sport->port.membase + UCR2);

+ /* disable the rx errors interrupts */
+ temp = readl(sport->port.membase + UCR4);
+ temp &= ~UCR4_OREN;
+ writel(temp, sport->port.membase + UCR4);
+
/* tell the DMA to receive the data. */
start_rx_dma(sport);
}
@@ -961,6 +967,7 @@ static void dma_rx_callback(void *data)

if (status == DMA_ERROR) {
dev_err(sport->port.dev, "DMA transaction error.\n");
+ clear_rx_errors(sport);
return;
}

@@ -1057,6 +1064,31 @@ static int start_rx_dma(struct imx_port *sport)
return 0;
}

+static void clear_rx_errors(struct imx_port *sport)
+{
+ unsigned int status_usr1, status_usr2;
+
+ status_usr1 = readl(sport->port.membase + USR1);
+ status_usr2 = readl(sport->port.membase + USR2);
+
+ if (status_usr2 & USR2_BRCD) {
+ sport->port.icount.brk++;
+ writel(USR2_BRCD, sport->port.membase + USR2);
+ } else if (status_usr1 & USR1_FRAMERR) {
+ sport->port.icount.frame++;
+ writel(USR1_FRAMERR, sport->port.membase + USR1);
+ } else if (status_usr1 & USR1_PARITYERR) {
+ sport->port.icount.parity++;
+ writel(USR1_PARITYERR, sport->port.membase + USR1);
+ }
+
+ if (status_usr2 & USR2_ORE) {
+ sport->port.icount.overrun++;
+ writel(USR2_ORE, sport->port.membase + USR2);
+ }
+
+}
+
#define TXTL_DEFAULT 2 /* reset default */
#define RXTL_DEFAULT 1 /* reset default */
#define TXTL_DMA 8 /* DMA burst setting */
--
2.8.3