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Message-Id: <1332842162-26113-1-git-send-email-tomoya.rohm@gmail.com>
Date: Tue, 27 Mar 2012 18:56:02 +0900
From: Tomoya MORINAGA <tomoya.rohm@...il.com>
To: Alan Cox <alan@...ux.intel.com>,
Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
linux-serial@...r.kernel.org, linux-kernel@...r.kernel.org
Cc: qi.wang@...el.com, yong.y.wang@...el.com, joel.clark@...el.com,
kok.howg.ewe@...el.com, Tomoya MORINAGA <tomoya.rohm@...il.com>
Subject: [PATCH] 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: Tomoya MORINAGA <tomoya.rohm@...il.com>
---
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 803847b..e297b7c 100644
--- a/drivers/tty/serial/pch_uart.c
+++ b/drivers/tty/serial/pch_uart.c
@@ -1452,8 +1452,10 @@ static int pch_uart_verify_port(struct uart_port *port,
__func__);
return -EOPNOTSUPP;
#endif
- priv->use_dma = 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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