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Subject[PATCH v2][RESEND] pch_uart: Fix dma channel unallocated issue
Date
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: Tomoya MORINAGA <tomoya.rohm@gmail.com>
---
v2: Re-create this patch for 3.4-rc2.
(RESEND) 1st v2 was sent to stable@vger.kernel.org. So, resend this patch
with correct destination address.
---
drivers/tty/serial/pch_uart.c | 4 +++-
1 files changed, 3 insertions(+), 1 deletions(-)

diff --git a/drivers/tty/serial/pch_uart.c b/drivers/tty/serial/pch_uart.c
index 08b9962..80a32cf 100644
--- a/drivers/tty/serial/pch_uart.c
+++ b/drivers/tty/serial/pch_uart.c
@@ -1440,9 +1440,11 @@ 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;
--
1.7.7.6


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