diff options
| -rw-r--r-- | drivers/serial/bfin_5xx.c | 31 |
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) 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; |