be more careful about mite transfer counts

diff --git a/comedi/drivers/mite.c b/comedi/drivers/mite.c
index 1213f1587592bb917c41059cff242e96e45d165f..fe00bf7c3a1ac90fbced988670b74965da65af38 100644 (file)
--- a/comedi/drivers/mite.c
+++ b/comedi/drivers/mite.c
@@ -305,9 +305,6 @@ void mite_prep_dma( struct mite_struct *mite, unsigned int channel,
         * of buf_int_ptr and buf_int_count at each interrupt.  A
         * better method is to poll the MITE before each user
         * "read()" to calculate the number of bytes available.
-        * mite_bytes_transferred(), mite_bytes_read(), and
-        * mite_bytes_in_transit() are provided to get the number
-        * of bytes transferred by the mite so far.
         */
        chcr |= CHCR_SET_LC_IE;
 
@@ -367,25 +364,54 @@ void mite_prep_dma( struct mite_struct *mite, unsigned int channel,
        MDPRINTK("exit mite_prep_dma\n");
 }
 
-unsigned int mite_bytes_read(struct mite_struct *mite, unsigned int chan)
+u32 mite_device_bytes_transferred(struct mite_struct *mite, unsigned int chan)
 {
-       return readl(mite->mite_io_addr+MITE_DAR(chan));
+       return readl(mite->mite_io_addr + MITE_DAR(chan));
 }
 
-unsigned int mite_bytes_in_transit(struct mite_struct *mite, unsigned int chan)
+u32 mite_bytes_in_transit(struct mite_struct *mite, unsigned int chan)
 {
        return readl(mite->mite_io_addr + MITE_FCR(chan)) & 0x000000FF;
 }
 
-unsigned int mite_bytes_transferred(struct mite_struct *mite, unsigned int chan)
+// returns lower bound for number of bytes transferred from device to memory
+u32 mite_bytes_written_to_memory_lb(struct mite_struct *mite, unsigned int chan)
 {
-       unsigned int bytes_read;
+       u32 device_byte_count;
 
-       bytes_read = mite_bytes_read( mite, chan );
-       /* to avoid race, we want to read bytes read before reading bytes
-        * in transit */
+       device_byte_count = mite_device_bytes_transferred(mite, chan);
        rmb();
-       return bytes_read - mite_bytes_in_transit( mite, chan );
+       return device_byte_count - mite_bytes_in_transit(mite, chan);
+}
+
+// returns upper bound for number of bytes transferred from device to memory
+u32 mite_bytes_written_to_memory_ub(struct mite_struct *mite, unsigned int chan)
+{
+       u32 in_transit_count;
+
+       in_transit_count = mite_bytes_in_transit(mite, chan);
+       rmb();
+       return mite_device_bytes_transferred(mite, chan) - in_transit_count;
+}
+
+// returns lower bound for number of bytes read from memory for transfer to device
+u32 mite_bytes_read_from_memory_lb(struct mite_struct *mite, unsigned int chan)
+{
+       u32 device_byte_count;
+
+       device_byte_count = mite_device_bytes_transferred(mite, chan);
+       rmb();
+       return device_byte_count + mite_bytes_in_transit(mite, chan);
+}
+
+// returns upper bound for number of bytes read from memory for transfer to device
+u32 mite_bytes_read_from_memory_ub(struct mite_struct *mite, unsigned int chan)
+{
+       u32 in_transit_count;
+
+       in_transit_count = mite_bytes_in_transit(mite, chan);
+       rmb();
+       return mite_device_bytes_transferred(mite, chan) + in_transit_count;
 }
 
 int mite_dma_tcr(struct mite_struct *mite, unsigned int channel)
@@ -566,8 +592,10 @@ EXPORT_SYMBOL(mite_devices);
 EXPORT_SYMBOL(mite_list_devices);
 EXPORT_SYMBOL(mite_prep_dma);
 EXPORT_SYMBOL(mite_buf_change);
-EXPORT_SYMBOL(mite_bytes_transferred);
-EXPORT_SYMBOL(mite_bytes_read);
+EXPORT_SYMBOL(mite_bytes_written_to_memory_lb);
+EXPORT_SYMBOL(mite_bytes_written_to_memory_ub);
+EXPORT_SYMBOL(mite_bytes_read_from_memory_lb);
+EXPORT_SYMBOL(mite_bytes_read_from_memory_ub);
 EXPORT_SYMBOL(mite_bytes_in_transit);
 #ifdef DEBUG_MITE
 EXPORT_SYMBOL(mite_decode);

diff --git a/comedi/drivers/mite.h b/comedi/drivers/mite.h
index 2ad27ed95d59daa4da41259914a53e057c86a926..dd59804586a6a0a9cc93ca1dea62c61882ef33ae 100644 (file)
--- a/comedi/drivers/mite.h
+++ b/comedi/drivers/mite.h
@@ -92,9 +92,11 @@ void mite_list_devices(void);
 int mite_dma_tcr(struct mite_struct *mite, unsigned int channel );
 void mite_dma_arm(struct mite_struct *mite, unsigned int channel );
 void mite_dma_disarm(struct mite_struct *mite, unsigned int channel );
-unsigned int mite_bytes_transferred(struct mite_struct *mite, unsigned int chan);
-unsigned int mite_bytes_read(struct mite_struct *mite, unsigned int chan);
-unsigned int mite_bytes_in_transit(struct mite_struct *mite, unsigned int chan);
+u32 mite_bytes_written_to_memory_lb(struct mite_struct *mite, unsigned int chan);
+u32 mite_bytes_written_to_memory_ub(struct mite_struct *mite, unsigned int chan);
+u32 mite_bytes_read_from_memory_lb(struct mite_struct *mite, unsigned int chan);
+u32 mite_bytes_read_from_memory_ub(struct mite_struct *mite, unsigned int chan);
+u32 mite_bytes_in_transit(struct mite_struct *mite, unsigned int chan);
 
 #if 0
 unsigned long mite_ll_from_kvmem(struct mite_struct *mite,comedi_async *async,int len);

diff --git a/comedi/drivers/ni_mio_common.c b/comedi/drivers/ni_mio_common.c
index 56d7f074f6526b69578115d204e985996184874b..648c8878363049f000555e0fb365663ec21cfb27 100644 (file)
--- a/comedi/drivers/ni_mio_common.c
+++ b/comedi/drivers/ni_mio_common.c
@@ -410,13 +410,9 @@ static void ni_sync_ai_dma(struct mite_struct *mite, comedi_device *dev)
        // write alloc as much as we can
        comedi_buf_write_alloc(s->async, s->async->prealloc_bufsz);
 
-       nbytes = mite_bytes_transferred(mite, AI_DMA_CHAN);
+       nbytes = mite_bytes_written_to_memory_lb(mite, AI_DMA_CHAN);
        rmb();
-       /* We use mite_bytes_read() for the overrun check
-        * because it returns an upper bound, and mite_bytes_transferred
-        * returns a lower bound on the number of bytes actually
-        * transferred */
-       if( (int)(mite_bytes_read(mite, AI_DMA_CHAN) - old_alloc_count) > 0 ){
+       if( (int)(mite_bytes_written_to_memory_ub(mite, AI_DMA_CHAN) - old_alloc_count) > 0 ){
                printk("ni_mio_common: DMA overwrite of free area\n");
                ni_ai_reset(dev,s);
                async->events |= COMEDI_CB_OVERFLOW;
@@ -445,29 +441,35 @@ static void mite_handle_b_linkc(struct mite_struct *mite, comedi_device *dev)
        int count;
        comedi_subdevice *s = dev->subdevices + 1;
        comedi_async *async = s->async;
-       unsigned int nbytes, new_write_count;
-
+       u32 nbytes_ub, nbytes_lb;
+       unsigned int new_write_count;
+       u32 stop_count = async->cmd.stop_arg * sizeof(sampl_t);
+       
        writel(CHOR_CLRLC, mite->mite_io_addr + MITE_CHOR(AO_DMA_CHAN));
 
        new_write_count = async->buf_write_count;
-
-       nbytes = mite_bytes_read(mite, AO_DMA_CHAN);
-       if( async->cmd.stop_src == TRIG_COUNT &&
-               (int) (nbytes - async->cmd.stop_arg * sizeof( sampl_t ) ) > 0 )
-               nbytes = async->cmd.stop_arg * sizeof( sampl_t );
-       if( (int)(nbytes - devpriv->last_buf_write_count) > 0 ){
+       mb();
+       nbytes_lb = mite_bytes_read_from_memory_lb(mite, AO_DMA_CHAN);
+       if(async->cmd.stop_src == TRIG_COUNT &&
+               (int) (nbytes_lb - stop_count) > 0)
+               nbytes_lb = stop_count;
+       mb();
+       nbytes_ub = mite_bytes_read_from_memory_ub(mite, AO_DMA_CHAN);
+       if(async->cmd.stop_src == TRIG_COUNT &&
+               (int) (nbytes_ub - stop_count) > 0)
+               nbytes_ub = stop_count;
+       if((int)(nbytes_ub - devpriv->last_buf_write_count) > 0){
                rt_printk("ni_mio_common: DMA underrun\n");
                ni_ao_reset(dev,s);
                async->events |= COMEDI_CB_OVERFLOW;
                return;
        }
-
+       mb();
        devpriv->last_buf_write_count = new_write_count;
 
-       count = nbytes - async->buf_read_count;
-       if( count < 0 ){
-               rt_printk("ni_mio_common: BUG: negative ao count\n");
-               count = 0;
+       count = nbytes_lb - async->buf_read_count;
+       if(count < 0){
+               return;
        }
        comedi_buf_read_free(async, count);