dealt with possible race between interrupt fifio half-full and external stop trigger

diff --git a/comedi/drivers/das1800.c b/comedi/drivers/das1800.c
index 4c58448c6365cda9940553b9e59af6f29f242451..f42f8975aca717829f03077fa605088b766a57ba 100644 (file)
--- a/comedi/drivers/das1800.c
+++ b/comedi/drivers/das1800.c
@@ -74,7 +74,6 @@ For safety reasons, the driver disables dma transfers if you enable
 
 TODO:
        Add support for analog out on 'ao' cards.
-       what happens on external stop source with dma turned off?
 */
 
 #include <linux/kernel.h>
@@ -124,7 +123,7 @@ TODO:
 #define   DMA_CH6_CH7             0x6
 #define   DMA_CH7_CH5             0x7
 #define   DMA_ENABLED             0x3  //mask used to determine if dma is enabled
-#define                DMA_DUAL                0x4
+#define   DMA_DUAL                0x4
 #define   IRQ3                    0x8
 #define   IRQ5                    0x10
 #define   IRQ7                    0x18
@@ -890,7 +889,8 @@ static void das1800_interrupt(int irq, void *d, struct pt_regs *regs)
                        das1800_handle_dma(dev, s);
                }
        }
-       else if(status & FHF)
+       // if fifo half full, and there has not an external stop trigger
+       else if((status & FHF) && !(status & CT0TC))
        {
                das1800_handle_fifo_half_full(dev, s);
        } else if(status & FNE)
@@ -1054,7 +1054,6 @@ static void das1800_handle_fifo_half_full(comedi_device *dev, comedi_subdevice *
                if(!unipolar);
                        dpnt += 1 << (thisboard->resolution - 1);
                write_to_buffer(dev, s, dpnt);
-               if(devpriv->count > 0) devpriv->count--;
        }
        return;
 }
@@ -1068,14 +1067,13 @@ static void das1800_handle_fifo_not_empty(comedi_device *dev, comedi_subdevice *
 
        while(inb(dev->iobase + DAS1800_STATUS) & FNE)
        {
+               if(devpriv->count == 0 && devpriv->forever == 0)
+                       break;
                dpnt = inw(dev->iobase + DAS1800_FIFO);
                /* convert to unsigned type if we are in a bipolar mode */
                if(!unipolar);
                        dpnt += 1 << (thisboard->resolution - 1);
                write_to_buffer(dev, s, dpnt);
-               if(devpriv->count > 0) devpriv->count--;
-               if(devpriv->count == 0 && devpriv->forever == 0)
-                       break;
        }
 
        return;
@@ -1098,6 +1096,7 @@ inline void write_to_buffer(comedi_device *dev, comedi_subdevice *s, sampl_t dat
        }
        s->async->buf_int_count += sizeof(sampl_t);
        s->async->buf_int_ptr += sizeof(sampl_t);
+       if(devpriv->count > 0) devpriv->count--;
 }
 
 void disable_das1800(comedi_device *dev)