staging: comedi: pcl818: fix (*cancel) when cmd->stop_src == TRIG_NONE

When using DMA, the async command (*cancel) operation is delayed until the
current DMA transfer is complete. When the DMA transfer finishes the interrupt
routine detects this and calls the (*cancel) again which should then cancel the
async command.

The current logic does not work when cmd->stop_src == TRIG_NONE. In this case
the (*cancel) function keeps delaying the cancel. The actual DMA does stop
because the DMA handler is not called to setup the next transfer but the
(*cancel) code is never executed.

Rename the 'irq_was_now_closed' flag in the private data to 'ai_cmd_canceled'
to clarify what it is.

Only set the flag in the (*cancel) when a DMA transfer is running and the
async command has not already been canceled. The interrupt routine then does
not need all the extra checks.

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/pcl818.c b/drivers/staging/comedi/drivers/pcl818.c
index c820df2aac4511ff57b7eaf2f62af3b430a443fb..6c91a7b424d8a6019fd2483cf7102ef446c88068 100644 (file)
--- a/drivers/staging/comedi/drivers/pcl818.c
+++ b/drivers/staging/comedi/drivers/pcl818.c
@@ -332,7 +332,7 @@ struct pcl818_private {
        unsigned int divisor2;
        unsigned int usefifo:1;
        unsigned int ai_cmd_running:1;
-       unsigned int irq_was_now_closed:1;
+       unsigned int ai_cmd_canceled:1;
 };
 
 static const unsigned int muxonechan[] = { 0x00, 0x11, 0x22, 0x33, 0x44, 0x55, 0x66, 0x77,     /*  used for gain list programming */
@@ -731,29 +731,22 @@ static irqreturn_t interrupt_pcl818(int irq, void *d)
        struct comedi_device *dev = d;
        struct pcl818_private *devpriv = dev->private;
        struct comedi_subdevice *s = dev->read_subdev;
-       struct comedi_cmd *cmd = &s->async->cmd;
 
        if (!dev->attached) {
                comedi_error(dev, "premature interrupt");
                return IRQ_HANDLED;
        }
 
-       if (devpriv->ai_cmd_running && devpriv->irq_was_now_closed) {
-               if ((cmd->stop_src == TRIG_NONE ||
-                   (cmd->stop_src == TRIG_COUNT && devpriv->ai_act_scan > 0)) &&
-                   (devpriv->ai_mode == INT_TYPE_AI1_DMA ||
-                    devpriv->ai_mode == INT_TYPE_AI3_DMA)) {
-                       /* The cleanup from ai_cancel() has been delayed
-                          until now because the card doesn't seem to like
-                          being reprogrammed while a DMA transfer is in
-                          progress.
-                        */
-                       devpriv->ai_act_scan = 0;
-                       s->cancel(dev, s);
-               }
-
+       if (devpriv->ai_cmd_canceled) {
+               /*
+                * The cleanup from ai_cancel() has been delayed
+                * until now because the card doesn't seem to like
+                * being reprogrammed while a DMA transfer is in
+                * progress.
+                */
+               devpriv->ai_act_scan = 0;
+               s->cancel(dev, s);
                outb(0, dev->iobase + PCL818_CLRINT);   /* clear INT request */
-
                return IRQ_HANDLED;
        }
 
@@ -820,7 +813,7 @@ static int pcl818_ai_cmd_mode(int mode, struct comedi_device *dev,
        devpriv->ai_act_scan = cmd->stop_arg;
        devpriv->ai_act_chan = 0;
        devpriv->ai_cmd_running = 1;
-       devpriv->irq_was_now_closed = 0;
+       devpriv->ai_cmd_canceled = 0;
        devpriv->act_chanlist_pos = 0;
        devpriv->dma_runs_to_end = 0;
 
@@ -1065,12 +1058,14 @@ static int pcl818_ai_cancel(struct comedi_device *dev,
        case INT_TYPE_AI3_DMA:
                if (cmd->stop_src == TRIG_NONE ||
                    (cmd->stop_src == TRIG_COUNT && devpriv->ai_act_scan > 0)) {
-                       /*
-                        * Wait for running dma transfer to end,
-                        * do cleanup in interrupt.
-                        */
-                       devpriv->irq_was_now_closed = 1;
-                       return 0;
+                       if (!devpriv->ai_cmd_canceled) {
+                               /*
+                               * Wait for running dma transfer to end,
+                               * do cleanup in interrupt.
+                               */
+                               devpriv->ai_cmd_canceled = 1;
+                               return 0;
+                       }
                }
                disable_dma(devpriv->dma);
        case INT_TYPE_AI1_INT:
@@ -1092,7 +1087,7 @@ static int pcl818_ai_cancel(struct comedi_device *dev,
                }
                devpriv->ai_cmd_running = 0;
                devpriv->ai_mode = 0;
-               devpriv->irq_was_now_closed = 0;
+               devpriv->ai_cmd_canceled = 0;
                break;
        }