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Commit af6d17cd authored by Tomoya MORINAGA's avatar Tomoya MORINAGA Committed by Greg Kroah-Hartman
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pch_uart: Fix dma channel unallocated issue 



This driver anticipates pch_uart_verify_port() is not called
during installation.
However, actually pch_uart_verify_port() is called during
installation.
As a result, memory access violation occurs like below.

0. initial value: use_dma=0
1. starup()
    - dma channel is not allocated because use_dma=0
2. pch_uart_verify_port()
    - Set use_dma=1
3. UART processing acts DMA mode because use_dma=1
     - memory access violation occurs!

This patch fixes the issue.

Solution:
Whenever pch_uart_verify_port() is called and then
dma channel is not allocated, the channel should be allocated.

Signed-off-by: default avatarTomoya MORINAGA <tomoya.rohm@gmail.com>
Cc: stable <stable@vger.kernel.org>
Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
parent 7a6fbc9a

drivers/tty/serial/pch_uart.c

+3 −1
Original line number Diff line number Diff line
@@ -1447,9 +1447,11 @@ static int pch_uart_verify_port(struct uart_port *port, 
			__func__);

		return -EOPNOTSUPP;

#endif

		priv->use_dma = 1;

		priv->use_dma_flag = 1;

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

		if (!priv->use_dma)

			pch_request_dma(port);

		priv->use_dma = 1;

	}



	return 0;