From 2704f807f9498054b8153002bafa3e818079e9a5 Mon Sep 17 00:00:00 2001 From: H Hartley Sweeten Date: Fri, 28 Mar 2014 09:20:58 -0700 Subject: [PATCH] staging: comedi: usbdux: bug fix for accessing 'ao_chanlist' in private data In usbdux_ao_cmd(), the channels for the command are transfered from the cmd->chanlist and stored in the private data 'ao_chanlist'. The channel numbers are bit-shifted when stored so that they become the "command" that is transfered to the device. The channel to command conversion results in the 'ao_chanlist' having these values for the channels: channel 0 -> ao_chanlist = 0x00 channel 1 -> ao_chanlist = 0x40 channel 2 -> ao_chanlist = 0x80 channel 3 -> ao_chanlist = 0xc0 The problem is, the usbduxsub_ao_isoc_irq() function uses the 'chan' value from 'ao_chanlist' to access the 'ao_readback' array in the private data. So instead of accessing the array as 0, 1, 2, 3, it accesses it as 0x00, 0x40, 0x80, 0xc0. Fix this by storing the raw channel number in 'ao_chanlist' and doing the bit-shift when creating the command. Fixes: a998a3db530bff80 "staging: comedi: usbdux: cleanup the private data 'outBuffer'" Cc: stable # 3.12 Signed-off-by: H Hartley Sweeten Reviewed-by: Ian Abbott Acked-by: Bernd Porr Signed-off-by: Greg Kroah-Hartman --- drivers/staging/comedi/drivers/usbdux.c | 9 +++------ 1 file changed, 3 insertions(+), 6 deletions(-) diff --git a/drivers/staging/comedi/drivers/usbdux.c b/drivers/staging/comedi/drivers/usbdux.c index 71db683098d6..b59af0303581 100644 --- a/drivers/staging/comedi/drivers/usbdux.c +++ b/drivers/staging/comedi/drivers/usbdux.c @@ -493,7 +493,7 @@ static void usbduxsub_ao_isoc_irq(struct urb *urb) /* pointer to the DA */ *datap++ = val & 0xff; *datap++ = (val >> 8) & 0xff; - *datap++ = chan; + *datap++ = chan << 6; devpriv->ao_readback[chan] = val; s->async->events |= COMEDI_CB_BLOCK; @@ -1040,11 +1040,8 @@ static int usbdux_ao_cmd(struct comedi_device *dev, struct comedi_subdevice *s) /* set current channel of the running acquisition to zero */ s->async->cur_chan = 0; - for (i = 0; i < cmd->chanlist_len; ++i) { - unsigned int chan = CR_CHAN(cmd->chanlist[i]); - - devpriv->ao_chanlist[i] = chan << 6; - } + for (i = 0; i < cmd->chanlist_len; ++i) + devpriv->ao_chanlist[i] = CR_CHAN(cmd->chanlist[i]); /* we count in steps of 1ms (125us) */ /* 125us mode not used yet */ -- 2.20.1