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authorSonic Zhang <sonic.zhang@analog.com>2009-06-11 13:42:57 +0100
committerLinus Torvalds <torvalds@linux-foundation.org>2009-06-11 08:51:04 -0700
commit35ff69357949cfff5c3d8e3038b77146872e3bd3 (patch)
treec0503527f7c27d8e042ba81157955fa24303049a /drivers/serial/bfin_5xx.c
parentf9d36da9cdc2504cd9bb6034cfaba0673ce2d6df (diff)
Blackfin Serial Driver: handle irregular DMA register status in auto start mode
This bug is caused by irregular behavior of DMA register CURR_X_COUNT and CURR_Y_COUNT when an auto restart uart rx DMA run to last byte in DMA buffer, trigger the interrupt and stay at this possiton. The status of current x and y is 0:7 instead of 512:8 or 0:8. The driver doesn't take care of this case when calculating the position. URL: http://blackfin.uclinux.org/gf/tracker/5063 Reported-by: Tomasz Motylewski <t.motylewski@bfad.de> Signed-off-by: Sonic Zhang <sonic.zhang@analog.com> Signed-off-by: Mike Frysinger <vapier@gentoo.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.c7
1 files changed, 4 insertions, 3 deletions
diff --git a/drivers/serial/bfin_5xx.c b/drivers/serial/bfin_5xx.c
index 676efdad371..854e96dfb07 100644
--- a/drivers/serial/bfin_5xx.c
+++ b/drivers/serial/bfin_5xx.c
@@ -490,7 +490,7 @@ void bfin_serial_rx_dma_timeout(struct bfin_serial_port *uart)
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;
- if (uart->rx_dma_nrows == DMA_RX_YCOUNT)
+ if (uart->rx_dma_nrows == DMA_RX_YCOUNT || x_pos == 0)
uart->rx_dma_nrows = 0;
x_pos = DMA_RX_XCOUNT - x_pos;
if (x_pos == DMA_RX_XCOUNT)
@@ -546,15 +546,16 @@ 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;
+ int x_pos, 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);
+ x_pos = get_dma_curr_xcount(uart->rx_dma_channel);
uart->rx_dma_nrows = DMA_RX_YCOUNT - uart->rx_dma_nrows;
- if (uart->rx_dma_nrows == DMA_RX_YCOUNT)
+ if (uart->rx_dma_nrows == DMA_RX_YCOUNT || x_pos == 0)
uart->rx_dma_nrows = 0;
pos = uart->rx_dma_nrows * DMA_RX_XCOUNT;