staging: comedi: adl_pci9118: clarify acquisition mode (ai_do) determination

The async command can operation in 4 modes in this driver.

Modes 1 and 4 use timers 1 and 2 as a cascaded timer to trigger each conversion.
Mode 1 begins the acquisitions immediately (scan_begin_src == TRIG_FOLLOW) and
Mode 4 begins after an external trigger (scan_begin_src == TRIG_EXT). Both modes
use a convert_src == TRIG_TIMER.

Mode 2 uses timers 1 and 2 in a double timed action (scan_begin_src == TRIG_TIMER
and convert_src != TRIG_EXT (TRIG_TIMER and TRIG_NOW are valid)).

Mode 3 does not use the timers. Each acquisition is triggered by an external
signal (scan_begin_src == TRIG_FOLLOW and convert_src == TRIG_EXT.

The (*do_cmdtest) validates the scan_begin_src as TRIG_FOLLOW, TRIG_TIMER,
or TRIG_EXT. Remove the invalid check for TRIG_INT in the (*do_cmd).

Clarify the logic used to determine the mode in the (*do_cmd).

Also, simplify pci9118_calc_divisors(). Call i8253_cascade_ns_to_timer() directly
in the (*do_cmd) for the mode 1 and mode 4 cases. Call pci9118_calc_divisors()
only for mode 2 acquisitions.

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>

diff --git a/drivers/staging/comedi/drivers/adl_pci9118.c b/drivers/staging/comedi/drivers/adl_pci9118.c
index 98922d735f007d367d19bf0793d520880abc6ce4..5961fefebf3ff8e451c888bb284cf12fd1b61938 100644 (file)
--- a/drivers/staging/comedi/drivers/adl_pci9118.c
+++ b/drivers/staging/comedi/drivers/adl_pci9118.c
@@ -513,7 +513,7 @@ static void pci9118_exttrg_enable(struct comedi_device *dev, bool enable)
                pci9118_amcc_int_ena(dev, false);
 }
 
-static void pci9118_calc_divisors(char mode, struct comedi_device *dev,
+static void pci9118_calc_divisors(struct comedi_device *dev,
                                  struct comedi_subdevice *s,
                                  unsigned int *tim1, unsigned int *tim2,
                                  unsigned int flags, int chans,
@@ -522,32 +522,21 @@ static void pci9118_calc_divisors(char mode, struct comedi_device *dev,
 {
        struct comedi_cmd *cmd = &s->async->cmd;
 
-       switch (mode) {
-       case 1:
-       case 4:
-               i8253_cascade_ns_to_timer(I8254_OSC_BASE_4MHZ,
-                                         div1, div2,
-                                         tim2, flags & CMDF_ROUND_NEAREST);
-               break;
-       case 2:
-               *div1 = *tim2 / I8254_OSC_BASE_4MHZ;
-                                               /* convert timer (burst) */
-               *div2 = *tim1 / I8254_OSC_BASE_4MHZ;    /* scan timer */
-               *div2 = *div2 / *div1;          /* major timer is c1*c2 */
-               if (*div2 < chans)
-                       *div2 = chans;
-
-               *tim2 = *div1 * I8254_OSC_BASE_4MHZ;    /* real convert timer */
-
-               if (cmd->convert_src == TRIG_NOW && !chnsshfront) {
-                       /* use BSSH signal */
-                       if (*div2 < (chans + 2))
-                               *div2 = chans + 2;
-               }
+       *div1 = *tim2 / I8254_OSC_BASE_4MHZ;    /* convert timer (burst) */
+       *div2 = *tim1 / I8254_OSC_BASE_4MHZ;    /* scan timer */
+       *div2 = *div2 / *div1;                  /* major timer is c1*c2 */
+       if (*div2 < chans)
+               *div2 = chans;
 
-               *tim1 = *div1 * *div2 * I8254_OSC_BASE_4MHZ;
-               break;
+       *tim2 = *div1 * I8254_OSC_BASE_4MHZ;    /* real convert timer */
+
+       if (cmd->convert_src == TRIG_NOW && !chnsshfront) {
+               /* use BSSH signal */
+               if (*div2 < (chans + 2))
+                       *div2 = chans + 2;
        }
+
+       *tim1 = *div1 * *div2 * I8254_OSC_BASE_4MHZ;
 }
 
 static void pci9118_start_pacer(struct comedi_device *dev, int mode)
@@ -1322,40 +1311,33 @@ static int pci9118_ai_cmd(struct comedi_device *dev, struct comedi_subdevice *s)
        pci9118_set_chanlist(dev, s, cmd->chanlist_len, cmd->chanlist,
                             devpriv->ai_add_front, devpriv->ai_add_back);
 
-       /* compute timers settings */
-       /*
-        * simplest way, fr=4Mhz/(tim1*tim2),
-        * channel manipulation without timers effect
-        */
-       if (((cmd->scan_begin_src == TRIG_FOLLOW) ||
-               (cmd->scan_begin_src == TRIG_EXT)) &&
-               (cmd->convert_src == TRIG_TIMER)) {
-                                       /* both timer is used for one time */
+       /* Determine acqusition mode and calculate timing */
+       if (cmd->scan_begin_src != TRIG_TIMER &&
+           cmd->convert_src == TRIG_TIMER) {
+               /* cascaded timers 1 and 2 are used for convert timing */
                if (cmd->scan_begin_src == TRIG_EXT)
                        devpriv->ai_do = 4;
                else
                        devpriv->ai_do = 1;
-               pci9118_calc_divisors(devpriv->ai_do, dev, s,
-                                     &cmd->scan_begin_arg, &cmd->convert_arg,
-                                     devpriv->ai_flags,
-                                     devpriv->ai_n_realscanlen,
-                                     &devpriv->ai_divisor1,
-                                     &devpriv->ai_divisor2,
-                                     devpriv->ai_add_front);
+               i8253_cascade_ns_to_timer(I8254_OSC_BASE_4MHZ,
+                                         &devpriv->ai_divisor1,
+                                         &devpriv->ai_divisor2,
+                                         &cmd->convert_arg,
+                                         devpriv->ai_flags &
+                                         CMDF_ROUND_NEAREST);
        }
 
-       if ((cmd->scan_begin_src == TRIG_TIMER) &&
-               ((cmd->convert_src == TRIG_TIMER) ||
-               (cmd->convert_src == TRIG_NOW))) {
-                                               /* double timed action */
+       if (cmd->scan_begin_src == TRIG_TIMER &&
+           cmd->convert_src != TRIG_EXT) {
                if (!devpriv->usedma) {
                        dev_err(dev->class_dev,
                                "cmd->scan_begin_src=TRIG_TIMER works only with bus mastering!\n");
                        return -EIO;
                }
 
+               /* double timed action */
                devpriv->ai_do = 2;
-               pci9118_calc_divisors(devpriv->ai_do, dev, s,
+               pci9118_calc_divisors(dev, s,
                                      &cmd->scan_begin_arg, &cmd->convert_arg,
                                      devpriv->ai_flags,
                                      devpriv->ai_n_realscanlen,
@@ -1364,8 +1346,9 @@ static int pci9118_ai_cmd(struct comedi_device *dev, struct comedi_subdevice *s)
                                      devpriv->ai_add_front);
        }
 
-       if ((cmd->scan_begin_src == TRIG_FOLLOW)
-           && (cmd->convert_src == TRIG_EXT)) {
+       if (cmd->scan_begin_src == TRIG_FOLLOW &&
+           cmd->convert_src == TRIG_EXT) {
+               /* external trigger conversion */
                devpriv->ai_do = 3;
        }