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Commit 8516c568 authored by Sonic Zhang's avatar Sonic Zhang Committed by Linus Torvalds
Browse files

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: default avatarSonic Zhang <sonic.zhang@analog.com>
Signed-off-by: default avatarMike Frysinger <vapier@gentoo.org>
Signed-off-by: default avatarBryan Wu <cooloney@kernel.org>
Signed-off-by: default avatarAlan Cox <alan@linux.intel.com>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
parent 4328e3e5

drivers/serial/bfin_5xx.c

+29 −2
Original line number Diff line number Diff line
@@ -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);



	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;