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Commit e41c0981 authored by Sebastian Andrzej Siewior's avatar Sebastian Andrzej Siewior Committed by Greg Kroah-Hartman
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tty: serial: pch: don't crash if DMA enabled but not loaded 



if the DMA driver isn't loaded "on time" then we crash in the irq handler:
| pch_uart 0000:02:0a.4: pch_request_dma:dma_request_channel FAILS(Tx)
| BUG: unable to handle kernel NULL pointer dereference at   (null)
| IP: [<c0676ed9>] pch_uart_interrupt+0x739/0x940

Signed-off-by: default avatarSebastian Andrzej Siewior <bigeasy@linutronix.de>
Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
parent 0da3336f

drivers/tty/serial/pch_uart.c

+7 −3
Original line number Diff line number Diff line
@@ -1508,11 +1508,15 @@ static int pch_uart_verify_port(struct uart_port *port, 
			__func__);

		return -EOPNOTSUPP;

#endif

		dev_info(priv->port.dev, "PCH UART : Use DMA Mode\n");

		if (!priv->use_dma)

		if (!priv->use_dma) {

			pch_request_dma(port);

			if (priv->chan_rx)

				priv->use_dma = 1;

		}

		dev_info(priv->port.dev, "PCH UART: %s\n",

				priv->use_dma ?

				"Use DMA Mode" : "No DMA");

	}



	return 0;

}