This is a note to let you know that I've just added the patch titled
staging: comedi: s626: fix continuous acquisition
to the 3.4-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
staging-comedi-s626-fix-continuous-acquisition.patch
and it can be found in the queue-3.4 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
>From e4317ce877a31dbb9d96375391c1c4ad2210d637 Mon Sep 17 00:00:00 2001
From: Ian Abbott <abbotti@xxxxxxxxx>
Date: Fri, 22 Mar 2013 15:16:29 +0000
Subject: staging: comedi: s626: fix continuous acquisition
From: Ian Abbott <abbotti@xxxxxxxxx>
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@xxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
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;
}
Patches currently in stable-queue which might be from abbotti@xxxxxxxxx are
queue-3.4/staging-comedi-s626-fix-continuous-acquisition.patch
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