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authorSonic Zhang <sonic.zhang@analog.com>2009-06-11 08:38:16 -0400
committerLinus Torvalds <torvalds@linux-foundation.org>2009-06-11 11:51:04 -0400
commit8516c568f25666a012ec4c859e640a76fc9b6ec0 (patch)
treef2d72c684c5f8c726f752643bdd88268df836b5b /drivers/serial/bfin_5xx.c
parent4328e3e5ef1ae3427a4f6863aa65916a68ec2dd9 (diff)
Blackfin Serial Driver: fix error while transferring large files
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>
Diffstat (limited to 'drivers/serial/bfin_5xx.c')
-rw-r--r--drivers/serial/bfin_5xx.c31
1 files changed, 29 insertions, 2 deletions
diff --git a/drivers/serial/bfin_5xx.c b/drivers/serial/bfin_5xx.c
index d86123e03391..65a4c07f6199 100644
--- a/drivers/serial/bfin_5xx.c
+++ b/drivers/serial/bfin_5xx.c
@@ -477,6 +477,15 @@ void bfin_serial_rx_dma_timeout(struct bfin_serial_port *uart)
477 477
478 spin_lock_irqsave(&uart->port.lock, flags); 478 spin_lock_irqsave(&uart->port.lock, flags);
479 479
480 /* 2D DMA RX buffer ring is used. Because curr_y_count and
481 * curr_x_count can't be read as an atomic operation,
482 * curr_y_count should be read before curr_x_count. When
483 * curr_x_count is read, curr_y_count may already indicate
484 * next buffer line. But, the position calculated here is
485 * still indicate the old line. The wrong position data may
486 * be smaller than current buffer tail, which cause garbages
487 * are received if it is not prohibit.
488 */
480 uart->rx_dma_nrows = get_dma_curr_ycount(uart->rx_dma_channel); 489 uart->rx_dma_nrows = get_dma_curr_ycount(uart->rx_dma_channel);
481 x_pos = get_dma_curr_xcount(uart->rx_dma_channel); 490 x_pos = get_dma_curr_xcount(uart->rx_dma_channel);
482 uart->rx_dma_nrows = DMA_RX_YCOUNT - uart->rx_dma_nrows; 491 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)
487 x_pos = 0; 496 x_pos = 0;
488 497
489 pos = uart->rx_dma_nrows * DMA_RX_XCOUNT + x_pos; 498 pos = uart->rx_dma_nrows * DMA_RX_XCOUNT + x_pos;
490 if (pos != uart->rx_dma_buf.tail) { 499 /* Ignore receiving data if new position is in the same line of
500 * current buffer tail and small.
501 */
502 if (pos > uart->rx_dma_buf.tail ||
503 uart->rx_dma_nrows < (uart->rx_dma_buf.tail/DMA_RX_XCOUNT)) {
491 uart->rx_dma_buf.head = pos; 504 uart->rx_dma_buf.head = pos;
492 bfin_serial_dma_rx_chars(uart); 505 bfin_serial_dma_rx_chars(uart);
493 uart->rx_dma_buf.tail = uart->rx_dma_buf.head; 506 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)
532{ 545{
533 struct bfin_serial_port *uart = dev_id; 546 struct bfin_serial_port *uart = dev_id;
534 unsigned short irqstat; 547 unsigned short irqstat;
548 int pos;
535 549
536 spin_lock(&uart->port.lock); 550 spin_lock(&uart->port.lock);
537 irqstat = get_dma_curr_irqstat(uart->rx_dma_channel); 551 irqstat = get_dma_curr_irqstat(uart->rx_dma_channel);
538 clear_dma_irqstat(uart->rx_dma_channel); 552 clear_dma_irqstat(uart->rx_dma_channel);
539 bfin_serial_dma_rx_chars(uart); 553
554 uart->rx_dma_nrows = get_dma_curr_ycount(uart->rx_dma_channel);
555 uart->rx_dma_nrows = DMA_RX_YCOUNT - uart->rx_dma_nrows;
556 if (uart->rx_dma_nrows == DMA_RX_YCOUNT)
557 uart->rx_dma_nrows = 0;
558
559 pos = uart->rx_dma_nrows * DMA_RX_XCOUNT;
560 if (pos > uart->rx_dma_buf.tail ||
561 uart->rx_dma_nrows < (uart->rx_dma_buf.tail/DMA_RX_XCOUNT)) {
562 uart->rx_dma_buf.head = pos;
563 bfin_serial_dma_rx_chars(uart);
564 uart->rx_dma_buf.tail = uart->rx_dma_buf.head;
565 }
566
540 spin_unlock(&uart->port.lock); 567 spin_unlock(&uart->port.lock);
541 568
542 return IRQ_HANDLED; 569 return IRQ_HANDLED;