Clarify the documentation in the comedi driver comment block to better explain the cmd triggert. Add a comment to step 2b of the (*do_cmdtest) to clarify the trigger check. Signed-off-by: H Hartley Sweeten <hsweeten@xxxxxxxxxxxxxxxxxxx> Cc: Ian Abbott <abbotti@xxxxxxxxx> Cc: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx> --- drivers/staging/comedi/drivers/das1800.c | 36 ++++++++++++++++++++++---------- 1 file changed, 25 insertions(+), 11 deletions(-) diff --git a/drivers/staging/comedi/drivers/das1800.c b/drivers/staging/comedi/drivers/das1800.c index 9153c9b..bfbc2bb 100644 --- a/drivers/staging/comedi/drivers/das1800.c +++ b/drivers/staging/comedi/drivers/das1800.c @@ -39,19 +39,32 @@ * [3] - DMA1 (optional, requires irq and dma0) * * analog input cmd triggers supported: - * start_src: TRIG_NOW | TRIG_EXT - * scan_begin_src: TRIG_FOLLOW | TRIG_TIMER | TRIG_EXT - * scan_end_src: TRIG_COUNT - * convert_src: TRIG_TIMER | TRIG_EXT - * (TRIG_EXT requires scan_begin_src == TRIG_FOLLOW) - * stop_src: TRIG_COUNT | TRIG_EXT | TRIG_NONE * - * scan_begin_src triggers TRIG_TIMER and TRIG_EXT use the card's - * 'burst mode' which limits the valid conversion time to 64 microseconds - * (convert_arg <= 64000). This limitation does not apply if scan_begin_src - * is TRIG_FOLLOW. + * start_src TRIG_NOW command starts immediately + * TRIG_EXT command starts on external pin TGIN * - * The maximum conversion speeds are not always achievable depending on the + * scan_begin_src TRIG_FOLLOW paced/external scans start immediately + * TRIG_TIMER burst scans start periodically + * TRIG_EXT burst scans start on external pin XPCLK + * + * scan_end_src TRIG_COUNT scan ends after last channel + * + * convert_src TRIG_TIMER paced/burst conversions are timed + * TRIG_EXT conversions on external pin XPCLK + * (requires scan_begin_src == TRIG_FOLLOW) + * + * stop_src TRIG_COUNT command stops after stop_arg scans + * TRIG_EXT command stops on external pin TGIN + * TRIG_NONE command runs until canceled + * + * If TRIG_EXT is used for both the start_src and stop_src, the first TGIN + * trigger starts the command, and the second trigger will stop it. If only + * one is TRIG_EXT, the first trigger will either stop or start the command. + * + * Minimum conversion speed is limited to 64 microseconds (convert_arg <= 64000) + * for 'burst' scans. This limitation does not apply for 'paced' scans. The + * maximum conversion speed is limited by the board (convert_arg >= ai_speed). + * Maximum conversion speeds are not always achievable depending on the * board setup (see user manual). * * NOTES: @@ -653,6 +666,7 @@ static int das1800_ai_cmdtest(struct comedi_device *dev, /* Step 2b : and mutually compatible */ + /* burst scans must use timed conversions */ if (cmd->scan_begin_src != TRIG_FOLLOW && cmd->convert_src != TRIG_TIMER) err |= -EINVAL; -- 2.6.3 _______________________________________________ devel mailing list devel@xxxxxxxxxxxxxxxxxxxxxx http://driverdev.linuxdriverproject.org/mailman/listinfo/driverdev-devel
