Messages in this thread Patch in this message | | | From | Ben Hutchings <> | Date | Sun, 07 Apr 2013 23:45:42 +0100 | Subject | [29/74] staging: comedi: s626: fix continuous acquisition |
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3.2.43-rc1 review patch. If anyone has any objections, please let me know.
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From: Ian Abbott <abbotti@mev.co.uk>
commit e4317ce877a31dbb9d96375391c1c4ad2210d637 upstream.
For the s626 driver, there is a bug in the handling of asynchronous commands on the AI subdevice when the stop source is `TRIG_NONE`. The command should run continuously until cancelled, but the interrupt handler stops the command running after the first scan.
The command set-up function `s626_ai_cmd()` contains this code:
switch (cmd->stop_src) { case TRIG_COUNT: /* data arrives as one packet */ devpriv->ai_sample_count = cmd->stop_arg; devpriv->ai_continous = 0; break; case TRIG_NONE: /* continous acquisition */ devpriv->ai_continous = 1; devpriv->ai_sample_count = 0; break; }
The interrupt handler `s626_irq_handler()` contains this code:
if (!(devpriv->ai_continous)) devpriv->ai_sample_count--; if (devpriv->ai_sample_count <= 0) { devpriv->ai_cmd_running = 0; /* ... */ }
So `devpriv->ai_sample_count` is only decremented for the `TRIG_COUNT` case, but `devpriv->ai_cmd_running` is set to 0 (and the command stopped) regardless.
Fix this in `s626_ai_cmd()` by setting `devpriv->ai_sample_count = 1` for the `TRIG_NONE` case. The interrupt handler will not decrement it so it will remain greater than 0 and the check for stopping the acquisition will fail.
Signed-off-by: Ian Abbott <abbotti@mev.co.uk> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> Signed-off-by: Ben Hutchings <ben@decadent.org.uk> --- drivers/staging/comedi/drivers/s626.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-)
--- a/drivers/staging/comedi/drivers/s626.c +++ b/drivers/staging/comedi/drivers/s626.c @@ -1882,7 +1882,7 @@ static int s626_ai_cmd(struct comedi_dev case TRIG_NONE: /* continous acquisition */ devpriv->ai_continous = 1; - devpriv->ai_sample_count = 0; + devpriv->ai_sample_count = 1; break; }
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