If we would like to send amount of data less than FIFO size we better would do
this via PIO mode. Otherwise the overhead could be significant.
Signed-off-by: Andy Shevchenko <andriy.shevchenko@xxxxxxxxxxxxxxx>
---
drivers/tty/serial/8250/8250_dma.c | 4 ++++
1 file changed, 4 insertions(+)
diff --git a/drivers/tty/serial/8250/8250_dma.c b/drivers/tty/serial/8250/8250_dma.c
index e508939..21d01a4 100644
--- a/drivers/tty/serial/8250/8250_dma.c
+++ b/drivers/tty/serial/8250/8250_dma.c
@@ -80,6 +80,10 @@ int serial8250_tx_dma(struct uart_8250_port *p)
return 0;
dma->tx_size = CIRC_CNT_TO_END(xmit->head, xmit->tail, UART_XMIT_SIZE);
+ if (dma->tx_size < p->port.fifosize) {
+ ret = -EINVAL;
+ goto err;
+ }
desc = dmaengine_prep_slave_single(dma->txchan,
dma->tx_addr + xmit->tail,
--
2.1.4
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