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staging: comedi: addi_apci_3120: prevent deadlock in apci3120_ao_insn_write()

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The DA_READY bit (0x0001) in the status register needs to be set before the
analog outputs can be updated.

Use comedi_timeout() to prevent a deadlock condition while waiting for the
DA_READY bit to get set.

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
2014-10-20 11:34:18 -07:00
committed by Greg Kroah-Hartman
parent 695f34cef3
commit ce987a8a8f
1 changed files with 17 additions and 4 deletions
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21
drivers/staging/comedi/drivers/addi-data/hwdrv_apci3120.c
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@@ -1923,21 +1923,34 @@ static int apci3120_do_insn_bits(struct comedi_device *dev,
return insn->n;
}
static int apci3120_ao_ready(struct comedi_device *dev,
struct comedi_subdevice *s,
struct comedi_insn *insn,
unsigned long context)
{
unsigned int status;
status = inw(dev->iobase + APCI3120_RD_STATUS);
if (status & 0x0001) /* waiting for DA_READY */
return 0;
return -EBUSY;
}
static int apci3120_ao_insn_write(struct comedi_device *dev,
struct comedi_subdevice *s,
struct comedi_insn *insn,
unsigned int *data)
{
unsigned int ui_Channel;
unsigned short us_TmpValue;
int ret;
ui_Channel = CR_CHAN(insn->chanspec);
data[0] = ((((ui_Channel & 0x03) << 14) & 0xC000) | data[0]);
do { /* Waiting of DA_READY BIT */
us_TmpValue = inw(dev->iobase + APCI3120_RD_STATUS) & 0x0001;
} while (us_TmpValue != 0x0001);
ret = comedi_timeout(dev, s, insn, apci3120_ao_ready, 0);
if (ret)
return ret;
if (ui_Channel <= 3)
/*