From ce987a8a8f86c063c6332da83dfa514a1582c2f3 Mon Sep 17 00:00:00 2001 From: H Hartley Sweeten Date: Mon, 20 Oct 2014 11:34:18 -0700 Subject: [PATCH] staging: comedi: addi_apci_3120: prevent deadlock in apci3120_ao_insn_write() 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 Reviewed-by: Ian Abbott Signed-off-by: Greg Kroah-Hartman --- .../comedi/drivers/addi-data/hwdrv_apci3120.c | 21 +++++++++++++++---- 1 file changed, 17 insertions(+), 4 deletions(-) diff --git a/drivers/staging/comedi/drivers/addi-data/hwdrv_apci3120.c b/drivers/staging/comedi/drivers/addi-data/hwdrv_apci3120.c index 0ba4b79cf515..b6c11fed957c 100644 --- a/drivers/staging/comedi/drivers/addi-data/hwdrv_apci3120.c +++ b/drivers/staging/comedi/drivers/addi-data/hwdrv_apci3120.c @@ -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) /* -- 2.30.2