staging: comedi: das16: use comedi_async 'scans_done' to detect EOA

Refactor das16_interrupt() to use the comedi_async 'scans_done' member to
detect the End-of-Acquisition for the async command. Use the helper function
comedi_nsamples_left() to determine if DMA needs to be restarted.

This allows the removal of the private data 'adc_byte_count' and fixes a
possible integer overflow issue when that value is calculated.

Signed-off-by: H Hartley Sweeten <hsweeten@visionengravers.com>
Reviewed-by: Ian Abbott <abbotti@mev.co.uk>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/drivers/staging/comedi/drivers/das16.c b/drivers/staging/comedi/drivers/das16.c
index 81fa28d3c0ca37a64b725d93083e2ac2733c0b4b..3a2a6ccffe3fb472c5605255f092b5d9a0f4f087 100644 (file)
--- a/drivers/staging/comedi/drivers/das16.c
+++ b/drivers/staging/comedi/drivers/das16.c
@@ -440,7 +440,6 @@ struct das16_private_struct {
        struct comedi_isadma    *dma;
        unsigned int            clockbase;
        unsigned int            ctrl_reg;
-       unsigned long           adc_byte_count;
        unsigned int            divisor1;
        unsigned int            divisor2;
        struct timer_list       timer;
@@ -458,8 +457,9 @@ static void das16_interrupt(struct comedi_device *dev)
        struct comedi_isadma *dma = devpriv->dma;
        struct comedi_isadma_desc *desc = &dma->desc[dma->cur_dma];
        unsigned long spin_flags;
+       unsigned int residue;
+       unsigned int nbytes;
        unsigned int nsamples;
-       int num_bytes, residue;
 
        spin_lock_irqsave(&dev->spinlock, spin_flags);
        if (!(devpriv->ctrl_reg & DAS16_CTRL_DMAE)) {
@@ -475,36 +475,33 @@ static void das16_interrupt(struct comedi_device *dev)
        residue = comedi_isadma_disable_on_sample(desc->chan,
                                                  comedi_bytes_per_sample(s));
 
-       /*  figure out how many points to read */
+       /* figure out how many samples to read */
        if (residue > desc->size) {
                dev_err(dev->class_dev, "residue > transfer size!\n");
-               async->events |= COMEDI_CB_ERROR | COMEDI_CB_EOA;
-               num_bytes = 0;
-       } else
-               num_bytes = desc->size - residue;
-
-       if (cmd->stop_src == TRIG_COUNT &&
-                                       num_bytes >= devpriv->adc_byte_count) {
-               num_bytes = devpriv->adc_byte_count;
-               async->events |= COMEDI_CB_EOA;
+               async->events |= COMEDI_CB_ERROR;
+               nbytes = 0;
+       } else {
+               nbytes = desc->size - residue;
        }
+       nsamples = comedi_bytes_to_samples(s, nbytes);
 
-       dma->cur_dma = 1 - dma->cur_dma;
-       devpriv->adc_byte_count -= num_bytes;
-
-       /* re-enable dma */
-       if (!(async->events & COMEDI_CB_CANCEL_MASK)) {
-               struct comedi_isadma_desc *nxt_desc = &dma->desc[dma->cur_dma];
+       /* restart DMA if more samples are needed */
+       if (nsamples && nsamples < comedi_nsamples_left(s, nsamples + 1)) {
+               struct comedi_isadma_desc *nxt_desc;
 
+               dma->cur_dma = 1 - dma->cur_dma;
+               nxt_desc = &dma->desc[dma->cur_dma];
                nxt_desc->size = nxt_desc->maxsize;
                comedi_isadma_program(nxt_desc);
        }
 
        spin_unlock_irqrestore(&dev->spinlock, spin_flags);
 
-       nsamples = comedi_bytes_to_samples(s, num_bytes);
        comedi_buf_write_samples(s, desc->virt_addr, nsamples);
 
+       if (cmd->stop_src == TRIG_COUNT && async->scans_done >= cmd->stop_arg)
+               async->events |= COMEDI_CB_EOA;
+
        comedi_handle_events(dev, s);
 }
 
@@ -688,8 +685,6 @@ static int das16_cmd_exec(struct comedi_device *dev, struct comedi_subdevice *s)
                return -1;
        }
 
-       devpriv->adc_byte_count = cmd->stop_arg * comedi_bytes_per_scan(s);
-
        if (devpriv->can_burst)
                outb(DAS1600_CONV_DISABLE, dev->iobase + DAS1600_CONV_REG);