Commit b609a595 authored by H Hartley Sweeten's avatar H Hartley Sweeten Committed by Greg Kroah-Hartman
Browse files

staging: comedi: adl_pci6208: don't deadlock while waiting to write ao data 



Remove a possible deadlock while waiting to write the analog output data.

The data transfer rate for every D/A data write in this driver is 2.2us.
Wait up to 10us for the board to be ready then and return -ETIME.

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 20fb170b

drivers/staging/comedi/drivers/adl_pci6208.c

+21 −4
Original line number Original line Diff line number Diff line
@@ -39,6 +39,7 @@ Configuration Options: not applicable, uses PCI auto config 
*/

*/





#include <linux/module.h>

#include <linux/module.h>

#include <linux/delay.h>

#include <linux/pci.h>

#include <linux/pci.h>





#include "../comedidev.h"

#include "../comedidev.h"
@@ -82,6 +83,21 @@ struct pci6208_private { 
	unsigned int ao_readback[PCI6208_MAX_AO_CHANNELS];

	unsigned int ao_readback[PCI6208_MAX_AO_CHANNELS];

};

};





static int pci6208_ao_wait_for_data_send(struct comedi_device *dev,

					 unsigned int timeout)

{

	unsigned int status;



	while (timeout--) {

		status = inw(dev->iobase + PCI6208_AO_STATUS);

		if ((status & PCI6208_AO_STATUS_DATA_SEND) == 0)

			return 0;

		udelay(1);

	}



	return -ETIME;

}



static int pci6208_ao_winsn(struct comedi_device *dev,

static int pci6208_ao_winsn(struct comedi_device *dev,

			    struct comedi_subdevice *s,

			    struct comedi_subdevice *s,

			    struct comedi_insn *insn, unsigned int *data)

			    struct comedi_insn *insn, unsigned int *data)
@@ -90,15 +106,16 @@ static int pci6208_ao_winsn(struct comedi_device *dev, 
	int chan = CR_CHAN(insn->chanspec);

	int chan = CR_CHAN(insn->chanspec);

	unsigned int invert = 1 << (16 - 1);

	unsigned int invert = 1 << (16 - 1);

	unsigned int val = devpriv->ao_readback[chan];

	unsigned int val = devpriv->ao_readback[chan];

	unsigned short status;

	int ret;

	int i;

	int i;





	for (i = 0; i < insn->n; i++) {

	for (i = 0; i < insn->n; i++) {

		val = data[i];

		val = data[i];





		do {

		/* D/A transfer rate is 2.2us, wait up to 10us */

			status = inw(dev->iobase + PCI6208_AO_STATUS);

		ret = pci6208_ao_wait_for_data_send(dev, 10);

		} while (status & PCI6208_AO_STATUS_DATA_SEND);

		if (ret)

			return ret;





		outw(val ^ invert, dev->iobase + PCI6208_AO_CONTROL(chan));

		outw(val ^ invert, dev->iobase + PCI6208_AO_CONTROL(chan));

	}

	}