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Blackfin Serial Driver: fix error while transferring large files

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Ignore receiving data if new position is in the same line of current
buffer tail and is small.  This should decrease overruns.

Signed-off-by: Sonic Zhang <sonic.zhang@analog.com>
Signed-off-by: Mike Frysinger <vapier@gentoo.org>
Signed-off-by: Bryan Wu <cooloney@kernel.org>
Signed-off-by: Alan Cox <alan@linux.intel.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This commit is contained in:
Sonic Zhang 2009-06-11 13:38:16 +01:00 committed by Linus Torvalds
parent 4328e3e5ef
commit 8516c568f2
1 changed files with 29 additions and 2 deletions
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31
drivers/serial/bfin_5xx.c
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@ -477,6 +477,15 @@ void bfin_serial_rx_dma_timeout(struct bfin_serial_port *uart)
spin_lock_irqsave(&uart->port.lock, flags);
/* 2D DMA RX buffer ring is used. Because curr_y_count and
* curr_x_count can't be read as an atomic operation,
* curr_y_count should be read before curr_x_count. When
* curr_x_count is read, curr_y_count may already indicate
* next buffer line. But, the position calculated here is
* still indicate the old line. The wrong position data may
* be smaller than current buffer tail, which cause garbages
* are received if it is not prohibit.
*/
uart->rx_dma_nrows = get_dma_curr_ycount(uart->rx_dma_channel);
x_pos = get_dma_curr_xcount(uart->rx_dma_channel);
uart->rx_dma_nrows = DMA_RX_YCOUNT - uart->rx_dma_nrows;
@ -487,7 +496,11 @@ void bfin_serial_rx_dma_timeout(struct bfin_serial_port *uart)
x_pos = 0;
pos = uart->rx_dma_nrows * DMA_RX_XCOUNT + x_pos;
if (pos != uart->rx_dma_buf.tail) {
/* Ignore receiving data if new position is in the same line of
* current buffer tail and small.
*/
if (pos > uart->rx_dma_buf.tail ||
uart->rx_dma_nrows < (uart->rx_dma_buf.tail/DMA_RX_XCOUNT)) {
uart->rx_dma_buf.head = pos;
bfin_serial_dma_rx_chars(uart);
uart->rx_dma_buf.tail = uart->rx_dma_buf.head;
@ -532,11 +545,25 @@ static irqreturn_t bfin_serial_dma_rx_int(int irq, void *dev_id)
{
struct bfin_serial_port *uart = dev_id;
unsigned short irqstat;
int pos;
spin_lock(&uart->port.lock);
irqstat = get_dma_curr_irqstat(uart->rx_dma_channel);
clear_dma_irqstat(uart->rx_dma_channel);
bfin_serial_dma_rx_chars(uart);
uart->rx_dma_nrows = get_dma_curr_ycount(uart->rx_dma_channel);
uart->rx_dma_nrows = DMA_RX_YCOUNT - uart->rx_dma_nrows;
if (uart->rx_dma_nrows == DMA_RX_YCOUNT)
uart->rx_dma_nrows = 0;
pos = uart->rx_dma_nrows * DMA_RX_XCOUNT;
if (pos > uart->rx_dma_buf.tail ||
uart->rx_dma_nrows < (uart->rx_dma_buf.tail/DMA_RX_XCOUNT)) {
uart->rx_dma_buf.head = pos;
bfin_serial_dma_rx_chars(uart);
uart->rx_dma_buf.tail = uart->rx_dma_buf.head;
}
spin_unlock(&uart->port.lock);
return IRQ_HANDLED;