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author | Ian Abbott <abbotti@mev.co.uk> | 2015-09-16 14:18:04 +0100 |
---|---|---|
committer | Luis Henriques <luis.henriques@canonical.com> | 2015-09-28 10:21:33 +0100 |
commit | a9fe999e472b0cadaebac838393d470ddc216b89 (patch) | |
tree | 3790a8482a822f9c5d4739ef280b35cc5ced063f | |
parent | 101ce408692c868bd31b537b01bebe5c68968069 (diff) | |
download | linux-stable-a9fe999e472b0cadaebac838393d470ddc216b89.tar.gz linux-stable-a9fe999e472b0cadaebac838393d470ddc216b89.tar.bz2 linux-stable-a9fe999e472b0cadaebac838393d470ddc216b89.zip |
staging: comedi: usbduxsigma: don't clobber ao_timer in command test
commit c04a1f17803e0d3eeada586ca34a6b436959bc20 upstream.
`devpriv->ao_timer` is used while an asynchronous command is running on
the AO subdevice. It also gets modified by the subdevice's `cmdtest`
handler for checking new asynchronous commands,
`usbduxsigma_ao_cmdtest()`, which is not correct as it's allowed to
check new commands while an old command is still running. Fix it by
moving the code which sets up `devpriv->ao_timer` into the subdevice's
`cmd` handler, `usbduxsigma_ao_cmd()`.
** This backported patch also moves the code that sets up
`devpriv->ao_sample_count` from `usbduxsigma_ao_cmdtest()` to
`usbduxsigma_ao_cmd()` for the same reason as above. (This was not
needed in the upstream commit.) **
Note that the removed code in `usbduxsigma_ao_cmdtest()` checked that
`devpriv->ao_timer` did not end up less that 1, but that could not
happen due because `cmd->scan_begin_arg` or `cmd->convert_arg` had
already been range-checked.
Also note that we tested the `high_speed` variable in the old code, but
that is currently always 0 and means that we always use "scan" timing
(`cmd->scan_begin_src == TRIG_TIMER` and `cmd->convert_src == TRIG_NOW`)
and never "convert" (individual sample) timing (`cmd->scan_begin_src ==
TRIG_FOLLOW` and `cmd->convert_src == TRIG_TIMER`). The moved code
tests `cmd->convert_src` instead to decide whether "scan" or "convert"
timing is being used, although currently only "scan" timing is
supported.
Fixes: fb1ef622e7a3 ("staging: comedi: usbduxsigma: tidy up analog output command support")
Signed-off-by: Ian Abbott <abbotti@mev.co.uk>
Signed-off-by: Luis Henriques <luis.henriques@canonical.com>
-rw-r--r-- | drivers/staging/comedi/drivers/usbduxsigma.c | 46 |
1 files changed, 20 insertions, 26 deletions
diff --git a/drivers/staging/comedi/drivers/usbduxsigma.c b/drivers/staging/comedi/drivers/usbduxsigma.c index e2c0c54e0910..823ccf6fef66 100644 --- a/drivers/staging/comedi/drivers/usbduxsigma.c +++ b/drivers/staging/comedi/drivers/usbduxsigma.c @@ -946,11 +946,26 @@ static int usbduxsigma_ao_cmdtest(struct comedi_device *dev, if (err) return 3; - /* Step 4: fix up any arguments */ + return 0; +} - /* we count in timer steps */ - if (high_speed) { - /* timing of the conversion itself: every 125 us */ +static int usbduxsigma_ao_cmd(struct comedi_device *dev, + struct comedi_subdevice *s) +{ + struct usbduxsigma_private *devpriv = dev->private; + struct comedi_cmd *cmd = &s->async->cmd; + int ret; + + down(&devpriv->sem); + + /* set current channel of the running acquisition to zero */ + s->async->cur_chan = 0; + + if (cmd->convert_src == TRIG_TIMER) { + /* + * timing of the conversion itself: every 125 us + * at high speed (not used yet) + */ devpriv->ao_timer = cmd->convert_arg / 125000; } else { /* @@ -959,12 +974,9 @@ static int usbduxsigma_ao_cmdtest(struct comedi_device *dev, */ devpriv->ao_timer = cmd->scan_begin_arg / 1000000; } - if (devpriv->ao_timer < 1) - err |= -EINVAL; - if (cmd->stop_src == TRIG_COUNT) { /* not continuous, use counter */ - if (high_speed) { + if (cmd->convert_src == TRIG_TIMER) { /* high speed also scans everything at once */ devpriv->ao_sample_count = cmd->stop_arg * cmd->scan_end_arg; @@ -981,24 +993,6 @@ static int usbduxsigma_ao_cmdtest(struct comedi_device *dev, devpriv->ao_sample_count = 0; } - if (err) - return 4; - - return 0; -} - -static int usbduxsigma_ao_cmd(struct comedi_device *dev, - struct comedi_subdevice *s) -{ - struct usbduxsigma_private *devpriv = dev->private; - struct comedi_cmd *cmd = &s->async->cmd; - int ret; - - down(&devpriv->sem); - - /* set current channel of the running acquisition to zero */ - s->async->cur_chan = 0; - devpriv->ao_counter = devpriv->ao_timer; if (cmd->start_src == TRIG_NOW) { |