From b436356dcc67a665da07441ab113e9a5652073e5 Mon Sep 17 00:00:00 2001 From: H Hartley Sweeten Date: Tue, 26 Jun 2012 18:12:15 -0700 Subject: [PATCH] staging: comedi: cb_pcidas: cleanup dac08_write() Reverse the logic of the test against the cached value so that the function only has one exit point. Make the logic of the dac write a bit clearer by create a local variable for the address used in the outw() calls and masking the value to write and setting the enable bits before doing the outw() calls. Add a comment just to make sure it's clear. Also, add a comment about the 'return 1;'. This should be insn->n which is the number of data parameters used to do the dac08_write_insn() but the insn is not a parameter to this function. Signed-off-by: H Hartley Sweeten Cc: Ian Abbott Signed-off-by: Greg Kroah-Hartman --- drivers/staging/comedi/drivers/cb_pcidas.c | 28 ++++++++++++---------- 1 file changed, 15 insertions(+), 13 deletions(-) diff --git a/drivers/staging/comedi/drivers/cb_pcidas.c b/drivers/staging/comedi/drivers/cb_pcidas.c index 1479325ab7ea..3ba75afe4e05 100644 --- a/drivers/staging/comedi/drivers/cb_pcidas.c +++ b/drivers/staging/comedi/drivers/cb_pcidas.c @@ -662,23 +662,25 @@ static int caldac_read_insn(struct comedi_device *dev, static int dac08_write(struct comedi_device *dev, unsigned int value) { struct cb_pcidas_private *devpriv = dev->private; + unsigned long cal_reg; - if (devpriv->dac08_value == value) - return 1; + if (devpriv->dac08_value != value) { + devpriv->dac08_value = value; - devpriv->dac08_value = value; + cal_reg = devpriv->control_status + CALIBRATION_REG; - outw(cal_enable_bits(dev) | (value & 0xff), - devpriv->control_status + CALIBRATION_REG); - udelay(1); - outw(cal_enable_bits(dev) | SELECT_DAC08_BIT | (value & 0xff), - devpriv->control_status + CALIBRATION_REG); - udelay(1); - outw(cal_enable_bits(dev) | (value & 0xff), - devpriv->control_status + CALIBRATION_REG); - udelay(1); + value &= 0xff; + value |= cal_enable_bits(dev); - return 1; + /* latch the new value into the caldac */ + outw(value, cal_reg); + udelay(1); + outw(value | SELECT_DAC08_BIT, cal_reg); + udelay(1); + outw(value, cal_reg); + udelay(1); + } + return 1; /* insn->n */ } static int dac08_write_insn(struct comedi_device *dev, -- 2.20.1