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| author | Tomoya MORINAGA <tomoya.rohm@gmail.com> | 2011-11-11 10:55:27 +0900 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@suse.de> | 2011-11-26 09:09:57 -0800 |
| commit | b74d0a317e75a602085cf73428bfe7ad456aee85 (patch) | |
| tree | 38e925e47c2afeebc22442114c933ef36f220c02 /drivers/tty | |
| parent | 3f04930ad551f504006e35ba5b6d6f717406638c (diff) | |
| download | kernel_samsung_smdk4412-b74d0a317e75a602085cf73428bfe7ad456aee85.zip kernel_samsung_smdk4412-b74d0a317e75a602085cf73428bfe7ad456aee85.tar.gz kernel_samsung_smdk4412-b74d0a317e75a602085cf73428bfe7ad456aee85.tar.bz2 | |
pch_uart: Fix DMA resource leak issue
commit 90f04c2926cfb5bf74533b0a7766bc896f6a0c0e upstream.
Changing UART mode PIO->DMA->PIO->DMA like below, pch_uart driver can't get
DMA channel resource.
setserial /dev/ttyPCH0 ^low_latency
setserial /dev/ttyPCH0 low_latency
CAUSE:
Changing mode using setserial command, ".startup" function which gets DMA
channel is called before ".verify_port" function which sets
dma-flag(use_dma/use_dma_flag) as 1.
PIO->DMA
.startup: Since dma-flag is 0, DMA channel is not requested.
.verify_port: dma-flag is set as 1.
.shutdown: N/A
DMA->PIO
.startup: Since dma-flag is 1, DMA channel is requested.
.verify_port: dma-flag is set as 0.
.shutdown: Since dma-flag is 0, DMA channel is not released.
This means DMA channel resource leak occurs.
Next time, this driver can't get DMA channel resource forever.
MODIFICATION:
Currently, when release DMA channel resource, this driver checks dma-flag.
However, this specification occurs the above issue.
This driver must check whether dma_request_channel is executed or not.
The values are saved in private data variable "chan_tx/chan_tx".
These variables mean if the value is NULL, DMA channel is not requested,
if not NULL, DMA channel is requested.
This patch fixes the issue.
Signed-off-by: Tomoya MORINAGA <tomoya.rohm@gmail.com>
Acked-by: Alan Cox <alan@linux.intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
Diffstat (limited to 'drivers/tty')
| -rw-r--r-- | drivers/tty/serial/pch_uart.c | 4 |
1 files changed, 2 insertions, 2 deletions
diff --git a/drivers/tty/serial/pch_uart.c b/drivers/tty/serial/pch_uart.c index df72c2c..f8c4ff6 100644 --- a/drivers/tty/serial/pch_uart.c +++ b/drivers/tty/serial/pch_uart.c @@ -625,6 +625,7 @@ static void pch_request_dma(struct uart_port *port) dev_err(priv->port.dev, "%s:dma_request_channel FAILS(Rx)\n", __func__); dma_release_channel(priv->chan_tx); + priv->chan_tx = NULL; return; } @@ -1212,8 +1213,7 @@ static void pch_uart_shutdown(struct uart_port *port) dev_err(priv->port.dev, "pch_uart_hal_set_fifo Failed(ret=%d)\n", ret); - if (priv->use_dma_flag) - pch_free_dma(port); + pch_free_dma(port); free_irq(priv->port.irq, priv); } |