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staging: comedi: pcl816: don't calc the timer divisors twice

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The timer divisors are calculated in the (*do_cmdtest) before the (*do_cmd)
is called by the comedi core. The extra sanity checks in the (*do_cmd) are
not necessary, the values returned from i8253_cascade_ns_to_timer() will be
greater than 1. Save the values in the private data so they don't need to be
recalced.

Refactor pcl816_start_pacer() to use the values from the private data.

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>
This commit is contained in:
H Hartley Sweeten 2014-02-19 10:11:23 -07:00 • committed by Greg Kroah-Hartman
commit f23068ec57
1 changed files with 13 additions and 28 deletions
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41
drivers/staging/comedi/drivers/pcl816.c
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@ -125,6 +125,8 @@ struct pcl816_private {
unsigned int ai_act_chanlist_len; /* how long is actual MUX list */
unsigned int ai_act_chanlist_pos; /* actual position in MUX list */
unsigned int ai_poll_ptr; /* how many sampes transfer poll */
unsigned int divisor1;
unsigned int divisor2;
};
/*
@ -139,9 +141,9 @@ static void setup_channel_list(struct comedi_device *dev,
static int pcl816_ai_cancel(struct comedi_device *dev,
struct comedi_subdevice *s);
static void pcl816_start_pacer(struct comedi_device *dev, bool load_counters,
unsigned int divisor1, unsigned int divisor2)
static void pcl816_start_pacer(struct comedi_device *dev, bool load_counters)
{
struct pcl816_private *devpriv = dev->private;
unsigned long timer_base = dev->iobase + PCL816_TIMER_BASE;
i8254_set_mode(timer_base, 0, 0, I8254_MODE1 | I8254_BINARY);
@ -153,8 +155,8 @@ static void pcl816_start_pacer(struct comedi_device *dev, bool load_counters,
udelay(1);
if (load_counters) {
i8254_write(timer_base, 0, 2, divisor2);
i8254_write(timer_base, 0, 1, divisor1);
i8254_write(timer_base, 0, 2, devpriv->divisor2);
i8254_write(timer_base, 0, 1, devpriv->divisor1);
}
}
@ -399,8 +401,9 @@ static irqreturn_t interrupt_pcl816(int irq, void *d)
static int pcl816_ai_cmdtest(struct comedi_device *dev,
struct comedi_subdevice *s, struct comedi_cmd *cmd)
{
struct pcl816_private *devpriv = dev->private;
int err = 0;
int tmp, divisor1 = 0, divisor2 = 0;
int tmp;
/* Step 1 : check if triggers are trivially valid */
@ -449,7 +452,8 @@ static int pcl816_ai_cmdtest(struct comedi_device *dev,
if (cmd->convert_src == TRIG_TIMER) {
tmp = cmd->convert_arg;
i8253_cascade_ns_to_timer(I8254_OSC_BASE_10MHZ,
&divisor1, &divisor2,
&devpriv->divisor1,
&devpriv->divisor2,
&cmd->convert_arg, cmd->flags);
if (cmd->convert_arg < 10000)
cmd->convert_arg = 10000;
@ -475,33 +479,14 @@ static int pcl816_ai_cmdtest(struct comedi_device *dev,
static int pcl816_ai_cmd(struct comedi_device *dev, struct comedi_subdevice *s)
{
struct pcl816_private *devpriv = dev->private;
unsigned int divisor1 = 0, divisor2 = 0, dma_flags, bytes, dmairq;
struct comedi_cmd *cmd = &s->async->cmd;
unsigned int dma_flags, bytes, dmairq;
unsigned int seglen;
if (devpriv->irq_blocked)
return -EBUSY;
if (cmd->convert_src == TRIG_TIMER) {
if (cmd->convert_arg < 10000)
cmd->convert_arg = 10000;
i8253_cascade_ns_to_timer(I8254_OSC_BASE_10MHZ,
&divisor1, &divisor2,
&cmd->convert_arg, cmd->flags);
/* PCL816 crash if any divisor is set to 1 */
if (divisor1 == 1) {
divisor1 = 2;
divisor2 /= 2;
}
if (divisor2 == 1) {
divisor2 = 2;
divisor1 /= 2;
}
}
pcl816_start_pacer(dev, false, 0, 0);
pcl816_start_pacer(dev, false);
seglen = check_channel_list(dev, s, cmd->chanlist, cmd->chanlist_len);
if (seglen < 1)
@ -549,7 +534,7 @@ static int pcl816_ai_cmd(struct comedi_device *dev, struct comedi_subdevice *s)
enable_dma(devpriv->dma);
}
pcl816_start_pacer(dev, true, divisor1, divisor2);
pcl816_start_pacer(dev, true);
dmairq = ((devpriv->dma & 0x3) << 4) | (dev->irq & 0x7);
switch (cmd->convert_src) {