staging: comedi: ni_mio_common: make more bits in ao_cmd1 reg be stateful

Bits NISTC_AO_CMD1_DAC0_UPDATE_MODE and NISTC_AO_CMD1_DAC1_UPDATE_MODE are
now saved in the local copy of the AO_CMD1 register.  This is more
appropriate than prior methods of setting these bits specifically _both_
in the ni_ao_cmd configuration function _and_ the ni_ao_inttrig trigger
function.  With this patch, the bits are only specifically called out now
in the ni_ao_cmd configuration function.  In the ni_ao_inttrig trigger
function, only the UI_ARM, UC_ARM, BC_ARM bits of the ao_cmd1 register are
specifically called out.  Each of these bits is a strobe bit, while the
DAC[0-1]_UPDATE_MODE bits are simple write bits.
Signed-off-by: NSpencer E. Olson <olsonse@umich.edu>
Reviewed-by: NIan Abbott <abbotti@mev.co.uk>
Signed-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/staging/comedi/drivers/ni_mio_common.c

@@ -2903,8 +2903,6 @@ static int ni_ao_inttrig(struct comedi_device *dev,
 	ni_stc_writew(dev, NISTC_AO_CMD1_UI_ARM |
 			   NISTC_AO_CMD1_UC_ARM |
 			   NISTC_AO_CMD1_BC_ARM |
-			   NISTC_AO_CMD1_DAC1_UPDATE_MODE |
-			   NISTC_AO_CMD1_DAC0_UPDATE_MODE |
 			   devpriv->ao_cmd1,
 		      NISTC_AO_CMD1_REG);
 
@@ -3081,9 +3079,11 @@ static int ni_ao_cmd(struct comedi_device *dev, struct comedi_subdevice *s)
 	}
 	ni_stc_writew(dev, devpriv->ao_mode1, NISTC_AO_MODE1_REG);
 
-	ni_stc_writew(dev, NISTC_AO_CMD1_DAC1_UPDATE_MODE |
-			   NISTC_AO_CMD1_DAC0_UPDATE_MODE,
-		      NISTC_AO_CMD1_REG);
+	/* Configure DAQ-STC for Timed update mode */
+	devpriv->ao_cmd1 |= NISTC_AO_CMD1_DAC1_UPDATE_MODE |
+			    NISTC_AO_CMD1_DAC0_UPDATE_MODE;
+	/* We are not using UPDATE2-->don't have to set DACx_Source_Select */
+	ni_stc_writew(dev, devpriv->ao_cmd1, NISTC_AO_CMD1_REG);
 
 	devpriv->ao_mode3 |= NISTC_AO_MODE3_STOP_ON_OVERRUN_ERR;
 	ni_stc_writew(dev, devpriv->ao_mode3, NISTC_AO_MODE3_REG);