Fixed problems with RTI_OVERRUN bit in ai read insn.

diff --git a/comedi/drivers/rti800.c b/comedi/drivers/rti800.c
index 83b13289e3393bbcea9a29d546da1755122c0f74..fda8f42ab5f8ebf194cb3be45c3875093265afd4 100644 (file)
--- a/comedi/drivers/rti800.c
+++ b/comedi/drivers/rti800.c
@@ -159,6 +159,7 @@ typedef struct {
        } dac0_coding, dac1_coding;
        comedi_lrange * ao_range_type_list[2];
        lsampl_t ao_readback[2];
+       int muxgain_bits;
 } rti800_private;
 
 #define devpriv ((rti800_private *)dev->private)
@@ -171,7 +172,7 @@ static irqreturn_t rti800_interrupt(int irq, void *dev PT_REGS_ARG)
 }
 
 // settling delay times in usec for different gains
-//static int gaindelay[]={10,20,40,80};
+static int gaindelay[]={10,20,40,80};
 
 static int rti800_ai_insn_read(comedi_device *dev,comedi_subdevice *s,
        comedi_insn *insn,lsampl_t *data)
@@ -180,18 +181,21 @@ static int rti800_ai_insn_read(comedi_device *dev,comedi_subdevice *s,
        int status;
        int chan = CR_CHAN(insn->chanspec);
        int gain = CR_RANGE(insn->chanspec);
-
+       unsigned muxgain_bits;
+       
        inb(dev->iobase + RTI800_ADCHI);
        outb(0,dev->iobase+RTI800_CLRFLAGS);
 
-       outb(chan | (gain << 5), dev->iobase + RTI800_MUXGAIN);
-
-       /* without a delay here, the RTI_OVERRUN bit
-        * gets set, and you will have an error.  Not
-        * sure if this is a long enough delay though.
-        * comedi_udelay( gaindelay[ gain ] ) definitely
-        * works */
-       comedi_udelay(1);
+       muxgain_bits = chan | (gain << 5);
+       if(muxgain_bits != devpriv->muxgain_bits)
+       {
+               devpriv->muxgain_bits = muxgain_bits;
+               outb(devpriv->muxgain_bits, dev->iobase + RTI800_MUXGAIN);
+               /* without a delay here, the RTI_OVERRUN bit
+                * gets set, and you will have an error. */
+               if(insn->n > 0)
+                       comedi_udelay(gaindelay[gain]);
+       }
 
        for(i=0;i<insn->n;i++){
                outb(0, dev->iobase + RTI800_CONVERT);
@@ -347,7 +351,8 @@ static int rti800_attach(comedi_device * dev, comedi_devconfig * it)
        devpriv->dac0_coding = it->options[6];
        devpriv->dac1_range = it->options[7];
        devpriv->dac1_coding = it->options[8];
-
+       devpriv->muxgain_bits = -1;
+       
        s=dev->subdevices+0;
        /* ai subdevice */
        s->type=COMEDI_SUBD_AI;