From 7fb8c56c7fa0fa11168d3788d4591951bec27f4b Mon Sep 17 00:00:00 2001 From: Heikki Krogerus Date: Thu, 5 Sep 2013 17:34:54 +0300 Subject: [PATCH] serial: 8250_dw: provide a filter for DMA channel detection The channel IDs are set to -1 by default. It will prevent dmaengine from trying to provide the first free channel if it fails to allocate exclusive channel. This will fix an issue with ACPI enumerated UARTs that do not support DMA but still end up getting a DMA channel incorrectly. Signed-off-by: Heikki Krogerus Signed-off-by: Greg Kroah-Hartman --- drivers/tty/serial/8250/8250_dw.c | 14 ++++++++++++++ 1 file changed, 14 insertions(+) diff --git a/drivers/tty/serial/8250/8250_dw.c b/drivers/tty/serial/8250/8250_dw.c index d7a405b12600..8edf7697fdb2 100644 --- a/drivers/tty/serial/8250/8250_dw.c +++ b/drivers/tty/serial/8250/8250_dw.c @@ -154,6 +154,14 @@ dw8250_do_pm(struct uart_port *port, unsigned int state, unsigned int old) pm_runtime_put_sync_suspend(port->dev); } +static bool dw8250_dma_filter(struct dma_chan *chan, void *param) +{ + struct dw8250_data *data = param; + + return chan->chan_id == data->dma.tx_chan_id || + chan->chan_id == data->dma.rx_chan_id; +} + static void dw8250_setup_port(struct uart_8250_port *up) { struct uart_port *p = &up->port; @@ -314,6 +322,12 @@ static int dw8250_probe(struct platform_device *pdev) uart.port.uartclk = clk_get_rate(data->clk); } + data->dma.rx_chan_id = -1; + data->dma.tx_chan_id = -1; + data->dma.rx_param = data; + data->dma.tx_param = data; + data->dma.fn = dw8250_dma_filter; + uart.port.iotype = UPIO_MEM; uart.port.serial_in = dw8250_serial_in; uart.port.serial_out = dw8250_serial_out; -- 2.39.2