From: Kazuya Mizuguchi <kazuya.mizuguchi.ks@xxxxxxxxxxx>
When the receive FIFO is not read in PIO transfer, rx_full interrupt
occurs frequently. This patch avoids it by discarding the receive FIFO.
Signed-off-by: Kazuya Mizuguchi <kazuya.mizuguchi.ks@xxxxxxxxxxx>
Signed-off-by: Yoshihiro Kaneko <ykaneko0929@xxxxxxxxx>
---
This patch is based on the tty-next branch of Greg Kroah-Hartman's tty
tree.
drivers/tty/serial/sh-sci.c | 22 ++++++++++++++++++++--
1 file changed, 20 insertions(+), 2 deletions(-)
diff --git a/drivers/tty/serial/sh-sci.c b/drivers/tty/serial/sh-sci.c
index b74a644..4ec3c32 100644
--- a/drivers/tty/serial/sh-sci.c
+++ b/drivers/tty/serial/sh-sci.c
@@ -121,6 +121,8 @@ struct sci_port {
#endif
struct notifier_block freq_transition;
+
+ u64 rxfull_time;
};
/* Function prototypes */
@@ -690,12 +692,26 @@ static void sci_receive_chars(struct uart_port *port)
return;
while (1) {
+ int rxfill = sci_rxfill(port);
+ u64 now = get_jiffies_64();
/* Don't copy more bytes than there is room for in the buffer */
- count = tty_buffer_request_room(tport, sci_rxfill(port));
+ count = tty_buffer_request_room(tport, rxfill);
/* If for any reason we can't copy more data, we're done! */
- if (count == 0)
+ if (count == 0) {
+ int n;
+ /* discarded bytes in RX-FIFO */
+ for (n = 0; n < rxfill; n++)
+ serial_port_in(port, SCxRDR);
+ if (rxfill > 0 &&
+ time_after64(now, sci_port->rxfull_time + (5*HZ))) {
+ sci_port->rxfull_time = now;
+ dev_warn(port->dev,
+ "RX-FIFO isn't read, so %d bytes is discarded.\n",
+ rxfill);
+ }
break;
+ }
if (port->type == PORT_SCI) {
char c = serial_port_in(port, SCxRDR);
@@ -2342,6 +2358,8 @@ static int sci_init_single(struct platform_device *dev,
dev_dbg(port->dev, "DMA tx %d, rx %d\n",
p->dma_slave_tx, p->dma_slave_rx);
+ sci_port->rxfull_time = get_jiffies_64();
+
return 0;
}
--
1.9.1
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