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Commit f23068ec authored by H Hartley Sweeten's avatar H Hartley Sweeten Committed by Greg Kroah-Hartman
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staging: comedi: pcl816: don't calc the timer divisors twice 



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: default avatarH Hartley Sweeten <hsweeten@visionengravers.com>
Reviewed-by: default avatarIan Abbott <abbotti@mev.co.uk>
Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
parent e5f376df

drivers/staging/comedi/drivers/pcl816.c

+13 −28
Original line number Diff line number Diff line
@@ -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) {