This is a note to let you know that I've just added the patch titled
pch_uart: Fix dma channel unallocated issue
to the 3.3-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
pch_uart-fix-dma-channel-unallocated-issue.patch
and it can be found in the queue-3.3 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <[email protected]> know about it.
>From af6d17cdc8c89aeb3101f0d27cd32fc0592b40b2 Mon Sep 17 00:00:00 2001
From: Tomoya MORINAGA <[email protected]>
Date: Thu, 12 Apr 2012 10:47:50 +0900
Subject: pch_uart: Fix dma channel unallocated issue
From: Tomoya MORINAGA <[email protected]>
commit af6d17cdc8c89aeb3101f0d27cd32fc0592b40b2 upstream.
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 <[email protected]>
Signed-off-by: Greg Kroah-Hartman <[email protected]>
---
drivers/tty/serial/pch_uart.c | 4 +++-
1 file changed, 3 insertions(+), 1 deletion(-)
--- a/drivers/tty/serial/pch_uart.c
+++ b/drivers/tty/serial/pch_uart.c
@@ -1366,9 +1366,11 @@ static int pch_uart_verify_port(struct u
__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;
Patches currently in stable-queue which might be from [email protected] are
queue-3.3/pch_uart-fix-dma-channel-unallocated-issue.patch
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